Environmental Protection Technology Series
DEVELOPMENT  OF MICROWAVE PLASMA
         DETOXIFICATION  PROCESS FOR
                    HAZARDOUS WASTES
                                   Phase  I
                  Municipal Environmental Research Laboratory
                       Office of Research and Development
                       U.S. Environmental Protection Agency
                              Cincinnati, Ohio 45268

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                RESEARCH REPORTING  SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

      1.  Environmental Health  Effects Research
      2.  Environmental Protection Technology
      3.  Ecological Research
      4.  Environmental Monitoring
      5.  Socioeconomic Environmental  Studies
      6.  Scientific and Technical Assessment Reports (STAR)
      7.  Interagency Energy-Environment Research and Development
      8.  "Special" Reports
      9.  Miscellaneous Reports

This report has  been assigned  to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research  performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.

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                                         EPA-600/2-77-030
                                         April 1977
           DEVELOPMENT OF MICROWAVE
         PLASMA DETOXIFICATION PROCESS
              FOR HAZARDOUS WASTES


                       PHASE I
                         by

                    Lionel J.  Bailin
                  Barry L. Hertzler

        Lockheed Palo Alto Research Laboratory
    LOCKHEED MISSILES & SPACE COMPANY, INC.
               Palo Alto, California 94304
                Contract No.  68-03-2190
                    Project Officer

                  Donald A.  Oberacker
       Solid and Hazardous Waste Research Division
      Municipal Environmental Research Laboratory
                 Cincinnati, Ohio 45267
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
      OFFICE OF RESEARCH AND DEVELOPMENT
     U.S. ENVIRONMENTAL PROTECTION AGENCY
               CINCINNATI,  OHIO  45268

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                             DISCLAIMER
    This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S.  Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U. S.  Environmental Protection Agency, nor
does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
                                  11

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                                  FOREWORD
     The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people.  Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.

     Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching for
solutions.  The Municipal Environmental Research Laboratory develops new and
improved technology and systems for the prevention, treatment, and management
of wastewater and solid and hazardous waste pollutant discharges from munici-
pal and community sources, for the preservation and treatment of public
drinking water supplies, and to minimize the adverse economic, social, health,
and aesthetic effects of pollution.  This publication is one of the products
of that research; a most vital communications link between the researcher and
the user community.

     This report describes a current and successful research and development
program whereby low-temperature microwave plasmas have been utilized to
detoxify efficiently and safely various hazardous pesticides and organic
wastes.  As a result of the attainment of project objectives, further scale-
up to larger size and capacity are under way at the pilot level, to be
followed by field verification, which is in the planning stages.
                              Francis T. Mayo
                              Director
                              Municipal Environmental Research Laboratory
                                      ill

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                              PREFACE

    Toxic organic substances, such as chlorinated hydrocarbons, and many
organophosphorus,  organonitrogen,  and organometallic compounds are com-
ponents of pesticides which have been withdrawn from use,  are obsolete, or
are components of hazardous industrial wastes.  These materials must be
managed or disposed of safely and effectively.   A primary responsibility of
the U.S.Environmental Protection Agency's Solid and Hazardous Waste
Research Division (SHWRD) has been to encourage  and support research and
development efforts  in the  area of hazardous waste disposal technology.  For
compounds of nominal  toxicity, laudable achievements have been accom-
plished in the technology of thermal destruction, chemical detoxification,
long-term encapsulation, and special landfill methods. However, with the
exception of high-cost  incinerator processing,  little or no new technology
has been developed for the  disposal of highly toxic,  refractory,  or extreme-
ly persistent wastes.  These materials are described in the 1974 EPA Re-
port to Congress,  Disposal of Hazardous Wastes, SW-115

    The microwave  plasma process described in this report is  a relatively
new application of what has been termed the "fourth state of matter", or the .
"plasma state".  It is the first practical application of a microwave dis-
charge to the decomposition of chemical compounds in significant quanti-
ties.
                                  IV

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                       TECHNICAL ABSTRACT

    The process of microwave decomposition of organic materials has been
applied to the detoxification/destruction of hazardous organic pesticides and
wastes.  The investigation began with the LPARL (Lockheed Palo Alto Re-
search Laboratory) laboratory-size plasma system.  Reaction efficiencies
and reaction product identities were obtained.  The detoxification process
was then expanded to a larger-scale,  continuous system employing custom-
designed,  commercially available hardware.

    A primary objective of the program was concerned with evaluation of
the effectiveness of the expanded-scale system using hazardous organic com-
pounds and wastes of current interest.  The products were identified to de-
termine whether the products  were innocuous or toxic,  and whether recovery
of useful materials as by-products was feasible.

Test Detoxifications in LPARL Unit

    The materials selected for study were passed through the LPARL lab-
oratory-size reactor, which handles  1  to 5 g/hr quantities,  to evaluate
conversion efficiency and to determine product identities.  Oxygen and argon
as carrier gases in combination with the toxic materials were tested and
evaluated.

    Conversion efficiency was calculated by means of mass-balance deter-
minations; and product identity by means of instrumental analysis,  e. g.,
infrared and mass spectroscopy.  The mechanisms of the detoxification
processes were postulated. Materials tested were pure Malathion liquid,
liquid PCB's, phenylmercuric acetate solution,  and methyl bromide gas.

Expanded-Scale Plasma System

    An expanded-volume  microwave plasma system was assembled from
custom-designed commercially available microwave  hardware.  The plasma
reactor tubes were constructed from transparent quartz.  Materials feed
systems for pure liquids,  slurries, and solutions were designed and built
to operate at reduced pressures, and installed with proper controls for
monitoring the addition rates.  Traps and separation units were installed as
needed for the decomposition products.

Test Detoxifications in Expanded-Scale System

    Liquid, slurry and solution materials were processed in the plasma
reactor to evaluate conversion efficiency, by-product recovery, and product

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identity.  The principal goal was to maximize throughput at greater than
99. 9% conversion.  Materials detoxified were pure Malathion liquid, liquid
PCB's, phenylmercuric acetate solution, and Kepone in the form of a solid
powder,  an aqueous slurry, and a solvent solution.  Metallic  mercury was
recovered as a by-product from the decomposition of phenylmercuric ace-
tate pesticide.  The Kepone and organomercurial pesticides were considered
as "real-world" systems because of their commercial sources of manufac-
ture,  and the nature of their composition as mixed system pesticides.
Throughput of the system was maximized at 450 to 3200 g/hr  (1 to 7 Ib/hr),
a multiplication factor of approximately 500 times that  of the  laboratory-
scale unit. Specific engineering tasks have therefore been outlined for the
design and construction of pilot-scale equipment and components for further
expansion of the system to 20 Ib/hr,  to be followed later by a 100 Ib/hr ver-
sion.

    This report was submitted in fulfillment of Contract No.  68-03-2190 by
the Lockheed Palo Alto Research Laboratory of Lockheed Missiles & Space
Co., Inc.,  under the sponsorship of the U. S. Environmental Protection
Agency.  The report covers the period April 1975 through May 1976.
                                  vi

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                        EXECUTIVE SUMMARY

    This report describes recent,  successful, research and development
efforts to utilize low-temperature microwave plasmas for the safe and effi-
cient detoxification of various hazardous wastes which threaten man and his
environment.  Approximately 10 million tons of such wastes are generated
yearly,  and are made up in part of the following types of materials:

    •  Pesticides which have been withdrawn from use

    •  Obsolete or below-specification toxic materials which cannot
       otherwise be utilized

    •  Industrial wastes from process streams,  chemicals, explosives,
       etc.

    Perhaps 10 to 20 percent of these wastes will need special methods for
disposal.  Some may be incinerated,  or disposed of by other means.  How-
ever,  those containing highly toxic compounds will require more sophisti-
cated techniques for disposal.

    The EPA Solid and Hazardous  Waste Research Division was attracted
to the microwave plasma process  during its search for new and novel means
for detoxification of hazardous and toxic waste streams.  Previously, a
Lockheed-built bench-scale device had won the attention and support of the
U.S. Army Edgewood Arsenal for the detoxification of trace nerve gas simu-
lants in contaminated air streams or interior building environments. Proof
of Concept tests were conducted during 1970-1972, with considerable suc-
cess.   Subsequently, the EPA supported a laboratory study to  test the effi-
cacy of the technique, using liquids and solids instead of the diluted gases.
This program included  actual pesticides and toxic materials instead of simu-
lants.

    During the first year's effort,  1975-1976, the process was remarkably
successful in detoxifying all  of the materials submitted for testing.  These
materials included a typical  organophosphorus pesticide (Malathion), a ro-
dent poison (methyl bromide), two polychlorinated biphenyl liquids (PCB's),
a mercury-containing fungicide (phenylmercuric acetate),  and Kepone, the
highly chlorinated pesticide of some notoriety.

    Scale-up operations were also successful.  Starting at from 1 to 5 grams
per hour in the laboratory-size plasma unit, the first level of throughput ex-
pansion was maximized at 450 to 3200 g/hr (1 to 7 Ib/hr) - a multiplication
factor of approximately 500 times.
                                  vn

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    Further benefits of the process are competitive, reasonable costs of
about $. 20/lb; the use of steam as well as oxygen as a carrier gas; and the
potential, verified in one case,  for resource recovery of valuable mate-
rials,  such as metallic mercury, from the organomercurial pesticide,
phenylmercuric acetate.

    Prospects for additional applications include the detoxification of car-
cinogenic compounds used by the U.S.  Navy in their colored smoke formu-
lations, the recovery of metal values from arsenic, cadmium, and zinc
organometallic pesticides,  and the decomposition of vinylchloride solid
wastes and related products. The process warrants further R&D effort,
namely,  additional scale-up to larger sizes and capacities that will be com-
patible with anticipated needs at the pilot- and field-verification levels. The
disposal of a few hundred pounds per hour will be evaluated and developed
as a safe, essentially simple, and economic process for materials of high
toxicity.  Field  demonstration testing and construction of systems at na-
tional or regional disposal sites  are long-term projected goals.
                                  Vlll

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                              CONTENTS

Foreword                                                            ^
Preface                                                              iv
Technical Abstract                                                    Y
Executive Summary                                                  yi|
Figures                                                              xi
Tables                                                              xiii
Acknowledgments                                                     x^v

   1.   Introduction                                                   1
   2.   Microwave Plasma Characteristics and Basic Process
       Description                                                    2
   3.   Equipment and Operating Procedures                            4
          3. 1   Laboratory-scale plasma unit                          4
          3. 2   Expanded-scale plasma system                         9
          3.3   Analytical methods                                    19
   4.   Selection of Pesticides and Hazardous Waste Materials          20
   5.   Results of  Laboratory-Scale Oxygen Plasma Reactions          22
          5. 1   Malathion                                            22
          5.2   Poly chlorinated biphenyls (PCB's)                     22
          5. 3   Methyl bromide                                       24
          5.4   Phenylmercuric acetate                               24
   6.   Results of Expanded-Scale Oxygen Plasma Reactions            25
          6. 1   Malathion                                            25
          6.2   Poly chlorinated biphenyls (PCB's)                     25
          6. 3   Phenylmercuric acetate                               27
          6.4   Kepone - a "real world" mixture                      27
          6. 5   Steam plasma detoxification of PMA-30                28
          6. 6   Process  costs calculated for PMA-30                  28
   7   Discussion of Results                                         32
          7. 1   Interpretation                                        32
          7. 2   Chemistry of oxygen plasma reactions                 33
                   7. 2. 1   Malathion - oxygen plasma reactions        33
                   7. 2. 2   PCB - oxygen plasma reactions             33
                   7. 2. 3   Methyl bromide - oxygen plasma
                           reactions                                   34
                   7. 2. 4   Phenylmercuric acetate - oxygen
                           plasma reactions                           34
                   7. 2. 5   Kepone - oxygen plasma reactions           34
          7. 3   Evaluation of ancillary equipment                      35
                   7. 3. 1   Materials feed techniques                   35
                   7. 3. 2   Packed bed technology                      37
                   7. 3. 3   Reduced pressure systems                  37
                   7. 3. 4   Analytical processes                       37
                                   IX

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   8.   Conclusions                                                  40
   9.   Recommendations                                             42

References                                                          44
Appendices

   A.  Mass Spectra                                                 45
       A. 1   Equipment                                              45
       A. 2   Pesticide and hazardous waste spectra                   49
             A. 2. 1   Malathion - oxygen plasma                      49
             A. 2. 2   Aroclor No.  1242 PCB - oxygen plasma          49
             A. 2. 3   Aroclor No.  1254 PCB - oxygen plasma          49
             A. 2. 4   Methyl bromide - oxygen plasma,  laboratory-
                     scale reactor,  quantitative analysis              49
             A. 2. 5   Troysan PMA-30, phenylmercurie acetate -
                     oxygen plasma                                  54
             A. 2. 6   Troysan PMA-30 - steam plasma                54
             A. 2. 7   Kepone - oxygen plasma                         54
   B.  Properties of Pesticides and Hazardous Wastes                 5^
       B. 1  Malathion                                               58
       B. 2  Poly chlorinated biphenyls                                59
       B. 3  Methyl bromide gas                                     59
       B. 4  Phenylmercuric acetate, PMA                           60
       B. 5  Kepone                                                 60
   C.  Chemical Reactions in  Argon and Hydrogen Plasmas            62
       C. 1  Malathion-argon  and malathion argon-oxygen plasmas     62
       C. 2   PCB - argon plasma reactions                           63
       C. 3   PCB - argon-oxygen plasma reactions                    63
        C.4   PCB - hydrogen plasma reactions                        63
        C. 5   Methyl bromide  - argon plasma reactions                64
        C. 6   Methyl bromide  - argon-oxygen plasma reactions         64

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                              FIGURES

Number                                                           Page

    1   Schematic diagram of laboratory microwave plasma
          system                                                    5

    2   Laboratory microwave plasma reactor system                 6

    3   Block diagram of microwave plasma system and
          related components                                         7

    4   Reduced pressure liquid feed system  — laboratory-
          scale                                                      8

    5   Quartz mesh basket within plasma reactor                    10

    6   Expanded-scale microwave plasma system —  schematic      11

    7   Expanded-scale microwave reactor —  hardware and
          associated electronics                                     13

    8   Series A microwave reactor system                          14

    9   Series B microwave reactor system                          15

   10   Series C microwave reactor system                          16

   11   Microwave power sources and control console                17

   12   Hazardous liquid injector system,  2 liter                     18

   13   Infrared spectra of Kepone acetone extract (curve A)  and
          its oxygen plasma reaction product  (curve B)                36

 A-1    Gas sampling system interface with plasma reactor and
          residual gas analyzer                                      46

 A-2    Mass spectrometer residual gas  analyzer  — variable
          leak valve and quadrupole head                              47

 A-3    Mass spectrometer residual gas  analyzer  — power
          supplies and vacuum gages                                 48
                                 XI

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Number                                                           Page

  A-4   Mass spectra of gaseous effluent from reaction of
          Malathion in oxygen plasma                                50

  A-5   Mass spectra of gaseous effluent from reaction of
          AroclorNo. 1242 PCB in oxygen plasma                    51

  A-6   Mass spectra of gaseous effluent from reaction of
          AroclorNo. 1254 PCB in oxygen plasma                    52
         •

  A-7   Mass spectroscopic analysis of methyl bromide
          oxygen plasma reaction                                    53

  A-8    Mass spectra of gaseous effluent from reaction of
         Troysan PMA-30 (phenylmercuric acetate methanol
         solution) in oxygen plasma                                 55

  A-9    Mass spectra of gaseous effluent from reaction of
         Troysan PMA-30 (phenylmercuric acetate methanol
         solution) in steam plasma                                  56

A-10    Mass spectra of gaseous effluent from reaction of
         Kepone-methanol/acetone in oxygen  plasma
                                  xu

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                               TABLES

Number                                                           Page
        Pesticides and Hazardous Waste Materials for
        Detoxification Tests                                         21

        Representative Laboratory-Scale Oxygen Plasma
         Reactions                                                 23

        Summary of Expanded-Scale Oxygen Plasma
         Reactions                                                 26

        Electrical and Carrier Gas Costs for Plasma Reactions
        in Series C Reactor Expanded-Scale System                   29

        Influence of Packed Bed on PMA-30 (Phenylmercuric
         Acetate) Conversion in Series C Plasma System              38
                                xiu

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                         ACKNOWLEDGMENTS

    This report was prepared by the Lockheed Palo Alto Research Labora-
tory,  Lockheed Missiles & Space Company, Inc.,  under U. S. Environmental
Protection Agency Contract No. 68-03-2190.  The work was performed in
the Laboratory of Chemistry,  Dr. Ernest L. Littauer,  Manager.
Dr. Lionel Bailin was Principal Investigator.   Major contributions to the
program were made by  Dr.  Barry L. Hertzler, plasma chemistry and mass
spectroscopy; Dr.  Gerald B. McCauley, infrared spectroscopy and related
analysis; Dr. Sid J.  Tetenbaum,  plasma physics; and Prof. Alex T. Bell,
University of California-Berkeley,  consultant,  plasma  reactions  and kinet-
ics.

    The Project Officer for the Environmental Protection  Agency was
Mr. Donald A.  Oberacker; Mr. Richard A.  Carnes served as Technical
Consultant.
                                 xiv

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                              SECTION 1

                           INTRODUCTION

    Although the microwave plasma detoxification of pesticides and hazard-
ous organic wastes is a relatively new process, investigations in plasma
chemistry began as early as 1874 (1).  In 1969, the  Lockheed Palo Alto
Research Laboratory (LPARL) was the first to investigate the application of
a microwave discharge to the  decomposition of toxic substances.

    A series of experiments was run in order to show feasibility for decom-
posing toxic gases by an electrical discharge (2).  Nerve gas simulants from
the U.S. Army Edgewood Arsenal were tested in the process during 1970  -
1972. Decompositions were achieved at near 100 percent levels in the lab-
oratory-size microwave cavity.  Although the decomposition efficiencies
were  high,  the throughput levels  were low,  about 1 to 5 g/hr (3, 4).  This
was the result of the small size of the reactor, which, however, utilized the
largest  cavity commercially available at the time.  When it  was determined
that large-volume microwave  applicators for expanded-scale plasma forma-
tion could be obtained on a custom basis from microwave hardware sup-
pliers (5),  the EPA Solid and  Hazardous Waste Research Division (SHWRD)
approved a feasibility study to test the process on several pesticides and
toxic  wastes.  In the following report are described the chemistry of the
detoxification reactions, an initial scale-up of the microwave hardware,  and
an evaluation  of the process in which up to 3200 g/hr (7 Ib/hr) were success-
fully decomposed to harmless or easily  disposable effluents.

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                                SECTION 2

MICROWAVE PLASMA CHARACTERISTICS & BASIC PROCESS DESCRIPTION

      In the present context, the term "microwave plasma"  denotes an ion-
 ized gas produced by microwave-induced electron reactions with neutral gas
 molecules. To a first approximation,  the electrons,  rather than thermal
 or radiative sources,  are the major contributors of energy for promotion
 of the chemical reactions.  The reactions are initiated by collisions between
 the reactant molecules and electrons in the plasma.   Organic free radicals
 are generally considered as the primary intermediates in this process.  The
 ionized gas, or plasma,  is also derived from the carrier gas which serves
 to transport the molecules into the plasma zone.

      When microwave frequencies of 100 to 10, 000 MHZ are used to induce
 ionization,  the field in the cavity oscillates so rapidly that the force on the
 electrons changes direction before the electrons can travel far; thus, the
 plasma is not swept out of the  discharge region (6).  Consequently, the
 electrons and ionized gas particles  remain within the discharge,  thereby
 contributing to the  chemical reactions in the plasma.

      Microwave plasmas show  many favorable characteristics (7) when com-
 pared with arc or electrode plasmas.   These include  the following:

      •  Production  of high ionization levels and molecular dissociation
        without excess heating of the contained gas

      •  Construction of reaction vessels which are simple,  free from
        contamination and less  subject to damage because of the
        absence of internal electrodes

      •  Production  of little or no electrical interference

     •  Absence of high voltages which can be easily contacted by
        operating personnel,  i.  e. absence of shock hazards.

     Microwave plasmas,  rather than radio frequency (RF) plasmas
 (1 to 100 MHz),  have been chosen because an RF discharge is difficult or
 impossible to develop in uniform cross-section (8).  This difficulty is de-
 tailed for gas  phase oxidation reactions in a  recent publication by Brown
 and Bell (9).  It appears that the ability of RF plasmas to interact fully with
 liquids and solids would therefore be severely compromised.

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    Since the plasma decomposition mechanism involves electronic rather
than thermal energy, the microwave applicator power coupling equipment
can be maintained at low temperatures,  that is, barely hot to the touch.
The materials of construction which are associated with furnace or inciner-
ator devices will therefore be generally unnecessary, and maintenance and
repair expenses should be low or nonexistent.

    The microwave plasmas described in this report were first produced in
a laboratory-size resonant cavity,  and then in three commercially-built
trough waveguide applicators.  Data on power levels utilized,  flow rates,
conversion efficiencies, and other plasma characteristics are enumerated in
the sections associated with the respective toxic materials. Process equip-
ment, hardware, and procedures are described in the next section.

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                               SECTION 3

              EQUIPMENT AND OPERATING PROCEDURES


 3. 1  LABORATORY-SCALE PLASMA UNIT

     During the initial stages of the program,  the plasma process was evalu-
 ated on pesticide materials in the same apparatus (4) which was utilized for
 decomposing the original organophosphonate simulants.  In this way, a valid
 transition would be possible when the materials were run in the larger size
 microwave  system,  which was then under construction.

     The laboratory unit was effectively the same as used previously,  with
 the exception that the feed techniques required modification for injection of
 liquids and  solutions.  A schematic line diagram is shown in Figure 1, and
 a photograph in Figure 2.  A block diagram of the microwave plasma detoxi-
 fication system is given in Figure  3.  This diagram applies to  the different
 size systems irrespective of the type of microwave applicator  or power
 source that is used.

     The microwave power source was a Varian PPS-2. 5A unit, which has
 an output frequency of 2450 MHz and develops up to 2. 5 kW.  A Microlite
 287 microwave leakage detector (Crystal Mfg.  Co.,  Oklahoma  City, OK) was
 used to monitor power leakage. Levels of leakage greater than 1 to 3 mW/cm2,
 which  is the lower limit of sensitivity of the apparatus,  were not detected in
 the immediate vicinity of the discharge tube.

    One materials-feed unit that was found to offer a practical solution for
 dropwise addition of liquids was a pressure-equalizing dropping funnel of
 approximately lOO-cm*  capacity installed at the input to the plasma reaction
 tube,  see Figure  4.

    The manipulative procedure involved,  first, filling the dropping funnel
 with the liquid to  be tested.  The lowest Teflon needle-valve stopcock is in
 the closed position.  The two remaining stopcocks are open. The entire  sys-
 tem is evacuated  to its minimum pressure,  about 0. 1 torr (mm Hg).   For
pure or sol vent-free liquids, such as pure Malathion or polychlorinated bi-
phenyls (PCB's),  an ice water sample receiving trap is located directly below
the plasma exhaust outlet, and liquid nitrogen-cooled traps are located down-
stream from the gas-sampling tube to collect condensable products and to
minimize contamination  of vacuum pump oil. Next, pressure is adjusted to
the desired  level by regulation of the main vacuum valve.  A Tesla coil is
generally used to ignite the  discharge.  When the Teflon  needle valve is

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 02
 GAS
 SUPPLY-

 Ar
 GAS
             VALVE
         FLOWMETER
1
 SUPPLY—^X)
VAC UUM
                 BACK-FILL LINES


                     QUADRUPOLE
                     GAS
                     ANALYZER
                                                       DROPPING
                                                       FUNNEL
                   LN COLD
                   TRAP
                                U
                MANOMETER
                          GAS
                          SAMPLING
                          TUBE
                                       PLASMA REACTOR

                                       DISCHARGE
                                       CAVITY
                                               MICROWAVE
                                               POWER
                                               SUPPLY
ICE-H2O
RECEIVING
TRAP
   Figure 1.  Schematic diagram of laboratory microwave plasma system

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r.
                          Figure 2.  Laboratory microwave plasma reactor system

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MATERIAL TO BE
DETOXIFIED AND
CARRIER GAS
SOURCE
  MICROWAVE
  PLASMA
  CAVITY
   PRODUCT
   RECEPTOR
    TUNING
    CIRCUITRY
MICROWAVE
POWER
SOURCE
ANALYTICAL
INSTRUMENTATION
FOR CHEMICAL
ANALYSIS
      Figure 3.  Block diagram of microwave plasma system
                and related components

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        30 CM
        85 CM
                              TEFLON NEEDLE-
                              VALVE STOPCOCK
                               TEFLON GASKET
                               QUICK DISCONNECT
                               TEFLON NEEDLE-
                               VALVE STOPCOCKS
                              TEFLON GASKET
                              QUJCK DISCONNECT
                              QUARTZ REACTOR TUBC
                              15 mm OD
Figure 4.  Reduced pressure liquid feed system — laboratory-scale
                             8

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opened, small drops fall under gravity through the quartz reaction tube.
Reaction product sampling is performed at the gas sampling tube,  and the
ice water and liquid nitrogen traps.

    Calculations indicated that the rate of fall of a drop of pesticide at zero
pressure through an average-size, 5-cm length plasma was 0. 1 sec,  using
for the approximation S = 1/2 g cr^ where S is the distance traveled,  g is
the gravitation constant (980 cm/sec2), and a is time in seconds.  The
actual residence time  or will be shorter, since the liquid  drops fall in the
same direction as that of the carrier gas. However,  since working pres-
sures on the order of 10 to  100 torr are more the rule,  the drag components
associated with  these pressures will lengthen the time over the estimated
free-fall time.  Therefore,  the extent of change in a  is related,  in addition
to the size of the liquid drop,  its density,  and the operating characteristics
of the carrier gas. Nevertheless,  it was apparent that a method would be
needed to increase the time for passage of the drop through the discharge.

    The technique by which this was accomplished utilized a quartz mesh
"basket" positioned at the center of the plasma zone.  Quartz mesh fibers
were loaded into the basket, and served as a  contact area for the drops.
The basket contained a sufficient number of holes to allow passage of the
effluent reaction products, as shown in Figure 5.  The process is continuous.
The residence time has been estimated at 1/2 to 1 sec,  the time for on-off
occurrences of reaction flashes inside the plasma zone.

    For gas feeds, such as methyl bromide,  the dropping funnel was  by-
passed, and the pesticide was fed directly into the plasma.

    With respect to additions of solids,  this was deferred until the larger
plasma system could be utilized.  It was  considered that development of  a
uniform method for feeding these materials into the narrow 15-mm o. d.
reaction tubes would not be productive relative to the  tasks prescribed for
evaluation in the expanded-scale system.

3. 2 EXPANDED-SCALE PLASMA SYSTEM

    A primary  objective of the-program was  the evaluation of the effective-
ness of an expanded-scale microwave plasma system  in processing hazard-
ous organic compounds,  wastes,  and pesticides of current interest.  In this
regard, the reaction products were identified to determine whether the
products were innocuous or toxic,  and whether there was  the possibility  for
recovery of useful  materials as by-products.

    The new microwave plasma applicator hardware and power supply-
equipment were supplied by Gerling Moore, Inc.,  Palo Alto,  California,
according to LPARL specifications.  Figure 6 shows a schematic diagram
of the microwave electronics and the associated process equipment.  The
principal difference between this system and  the laboratory model is  the
method of application of power. In the laboratory unit, the applicator uti-
lized a  resonant cavity,  Varian Model EC2-DRS2,  which was fed by a single
2. 5-kW power supply.  In the expanded-scale unit, rectangular trough wave-

-------
                        LIQUID PLUS CARRIER GAS
                    TEFLON
                    NEEDLE-VALVE
                    STOPCOCK
CARRIER GAS
              QUARTZ	
              REACTOR TUBE
                QUARTZ —
                BASKET
                                    [TEFLON GASKET QUICK
                                     DISCONNECT
                                  I
                                        •*•	PLASMA ZONE
                       TRAPS AND VACUUM PUMP
       Figure 5.  Quartz mesh basket within plasma reactor
                            10

-------
                  PESTICIDE
                  DROPPING
                  FUNNEL
MICROWAVE
POWER SOURCE
   MICROWAVE
   APPLICATOR
MICROWAVE
POWER SOURCE
x-PLASMA
 REACTOR
 TUBE
                   MASS
                   SPECTROMETER
                                       Y     Y
                                       I     I
                            FLOW METERS
              O SUPPLY  ALTERNATE
                Z        GAS SUPPLY


              3-WAY STOPCOCK
                                  MANOMETER
        COLD TRAP
          —\ ri—0__*.VACUUM PUMP
          (LN)  THROTTLE
           	1  VALVE
        RECEIVER^  COLD TRAP
Figure 6.  Expanded-scale microwave plasma system — schematic

                            11

-------
 guides were used.  Two 2. 5-kW power supplies fed the applicator, one sup-
 ply for each ridge.  A diagram of the microwave hardware and the associated
 electronics is shown in Figure 7.

     In the design of the applicator, three lengths were chosen for the evalu-
 ations.  These dimensions, exclusive of the two 21. 6 cm (8. 5 in. ) end-
 mounted radiation cutoff sections, are listed as follows:

                     • Series A      172 cm (68 in. )

                     • Series B       92 cm (36 in. )

                     • Series C       41 cm (16 in. )

 The interior dimensions (i. d. ) were the same for the three units: 21. 6 cm
 (8. 5 in. ) x 5. 7 cm (2. 24 in. ).   The i. d. of the cutoff guides was  5. 7 cm
 (2. 24 in. ) x 5. 7 cm (2. 24  in. ).  The ridges were 2. 5 cm (1 in. ) x 1. 25 cm
 (0. 5 in. ) attached at the narrower dimension axially to the 5. 7-cm section
 of the waveguide.

     In  Figures 8 through 10,  the three  systems are shown in assembly.
 Figure 8 shows the  applicator slanted approximately 30 degrees.  The vari-
 able positioning was feasible through use  of the flexible waveguides from the
 power supplies.  The master control unit, power supplies,  etc. , were in-
 stalled in a single movable rack (Figure 11).

     The reactor tubes were fabricated from transparent quartz with a
 1. 5 mm wall thickness,  and an o. d.  of 49 to 50 mm.  Raschig rings,  fabri-
 cated from quartz were used to fill the reactor in order to increase the
 residence time of the toxic materials in the plasma zone.  The ring dimen-
 sions ranged from 8 mm o. d.  x 4 mm length to 10 mm o. d. x 10  mm length.
 See Subsection 7. 3.  2 for development of optimum size of the rings.

     The pesticide dropping funnel was  a 2-liter version of the unit used for
 the laboratory-scale plasma tests (Figure 12).  For relatively volatile solu-
 tions,  a standard  250-cm3 volumetric dropping funnel was used for feeding
 directly into the reactor,  using atmospheric pressure above the solution
 (Figure 10).

    The vacuum pump was a Welch DuoSeal Model 1397 oil-sealed two-stage
 mechanical pump with a free-air displacement of 425 liter/mm.  Various
 traps were installed between the reactor output and the pump  for product
 collection and to maintain  cleanliness of the pump oil.   The output from the
 pump was passed through a stack exhaust  to the exit port on the roof of the
building.

    The following procedure for operating the larger plasma  systems was
only slightly different from that of the laboratory unit.   The system was eva-
cuated initially to  its minimum pressure,  about 1 torr.  With liquid-nitrogen
or other low-temperature  coolants in the trap condensers,  the flow of oxygen
was adjusted to maintain a pressure of about 10 torr.  With all water and


                                   12

-------
                            PART 5
PART 4
PART   PART
 3     2
                  PART 7
                                                   PART   PART
                            PART 5
PART 4
                  PART 6
1

w







III


1

1
II

1
n
LIIIIl



L
f
l

„
,'
Ijijiji'

                     PART
                     PART 2 - TRIPLE STUB TUNER
                     PART 3 - DUAL POWER MONITOR
                     PART 4 - FLEXIBLE WAVEGUIDE
                     PART 5- 3-PORT CIRCULATOR AND WATER LOAD
                     PART 6- VARIABLE POWER SOURCE AND CONTROL
                     PART 7 - 208 VOLT WATT-METER
Figure 7. Expanded-scale microwave reactor—hardware & associated electronics
                                    13

-------
 Flexible
 Wave
 Guide
Dual Power
Monitor
Flexible
Wave Guide
                                                                              Stack
                                                                              Exhaust
                                                                   Microwave  Plasma
                                                                   Applicator
                                                                           Carrier Gas
                                                                           Flow Meters
Pesticide
Dropping
Funnel
                                                                             LN Trap


                                                                           Bottom  End of
                                                                           Reactor Tube
                Figure  8.   Series A microwave reactor system

                                         14

-------

Figure 9.  Series B microwave reactor system




                     15

-------
Figure 10.  Series C microwave reactor system




                      16

-------

Figure 11.  Microwave power sources and control console
                         17

-------

                                  !


Figure 12.  Hazardous liquid injector system, 2 liter




                         18

-------
air cooling on, the microwave power sources were activated.  As soon as
the plasma ignited, about 1 sec, the flow of oxygen was increased, and the
pump throttle valve adjusted to achieve the desired combination of oxygen
flow and pressure. The microwave power was set to the desired level,  and
the tuning controls adjusted to give minimum reflected power. During the
procedure, a Holaday Model HI-1500- 3 microwave radiation monitor was
used to meter leakages in radiation,if any.  Levels greater than  1/2 mW/cm2
were not detected in the immediate vicinity of the discharge tube.

3. 3 ANALYTICAL METHODS

    Two principal methods were applied for materials analysis.   Of these,
mass spectroscopy yielded the maximum information on the identification of
the gaseous products produced in the plasma.  Infrared analysis  was used
for determination of effluent materials, which included solids and liquids,
deposited in the product receiver traps.   Gas chromatography and standard
quantitative techniques  for mass balance and heavy metals were  adopted as
required; details of these analyses are given in the section pertaining to the
individual pesticides.

    Mass spectrometric determinations were performed on a Varian Model
974-0002 residual gas  analyzer,  which includes an in-line continuous gas
sampling system. Two ranges of atomic mass units (amu) were  used as
applicable to the specific pesticide or waste:  1 to 50 amu (for gases such as
N2> °2,  CO2, CO, H2O, CH4,  C2H6, etc. ) and 1 to 250 amu maximum  (for
the detection of heavier gas, chlorinated hydrocarbons,  etc.). Appendix A
contains details of the  instrumentation and sampling procedures.

    Infrared spectrograms were determined on a Perkin-Elmer  621 IR
spectrophotometer with a range  of 4000 to 400 cm"1 (2. 5 to 25n).  Materials
to be analyzed were ground with KBr and compressed  to form KBr pellets
which were scanned over the prescribed spectrum.
                                  19

-------
                              SECTION 4

   SELECTION OF PESTICIDES AND HAZARDOUS WASTE MATERIALS

     The pesticides and hazardous wastes which were detoxified or decom-
posed by microwave plasmas are listed in Table 1,  and classified as follows:

     •  Organophosphorus compounds

     •  Halogenated hydrocarbons

     •  Heavy metal compounds

     The materials were tested in the form of a gas, as pure liquids, sol-
vent solutions,  aqueous slurries, and solid powder press cakes. Selections
were made by EPA and LPARL personnel by mutual agreement on the»basis
of diversity in form and chemical constitution, and on the extent of the\ en-
vironmental problems which were associated with the materials to be de-
toxified.  The properties and specifications of these materials are detailed
in Appendix B.

     In the following sections, a summary is presented  of the conversion/
detoxification data obtained from the oxygen plasma reactions performed in
the laboratory and expanded-scale systems.
                                  20

-------
TABLE 1.  PESTICIDES AND HAZARDOUS WASTE MATERIALS FOR DETOXIFICATION TESTS
Classification
Organophosphorus
Pesticide
Chlorinated Hydrocarbon
Waste
Brominated Hydrocarbon
Rodenticide
Heavy Metal Fungicide
Chlorinated Hydrocarbon
Pesticide
Material
Malathion
PCB's (Poly chlorinated
Biphenyls)
Methyl Bromide
Phenylmercuric Acetate
Kepone
Form Tested
Pure Liquid
Liquid Mixture
Commercial Gas
Commercial
Methanol Solution
1. Commercial Powder
2. Aqueous Dispersion
3. Methanol Solution
Manufacturer
American
Cyanamid
Monsanto
Matheson Gas
Troy Chemical
Allied Chemical
Grade or Type
ULV
Aroclor 1242
Aroclor 1254

TroysanPMA-30
80% Powder
Concentrate
Technical
Grade

-------
                               SECTION 5

   RESULTS OF LABORATORY-SCALE OXYGEN PLASMA REACTIONS

     The reactions in the laboratory plasma system,  i. e., the system of
1-5 g/hr throughput,  have illustrated the efficacy of the microwave plasma
process on pesticides and related materials, using oxygen as carrier gas.
Also evaluated were argon and hydrogen plasmas to determine their inter-
actions, if any, with  the toxic test materials.

     On the basis of the observed formation of extremely offensive mer-
captans from Malathion-type compounds in argon plasmas,  and the projec-
ted formation of dimethylmercury from phenylmercuric acetate or other
mercurials in argon and hydrogen plasmas, major efforts were applied to
the development of an oxygen carrier gas technology.  The reactions asso-
ciated with the argon and hydrogen plasmas are given in Appendix C.

     A summary of typical results from the laboratory unit is listed in
Table  2.
5. 1  MALATHION

     "Cythion" ULV Malathion, manufactured by the American Cyanamid
Company, was passed through 200 to 250 Watt oxygen plasmas at 100 to
120 torr,  using the quartz basket technique.  (See subsection 3. 2 for a des-
cription of the technique.) With the exception of a white etch zone and a
high viscosity water-white liquid that formed below the plasma,  all the
products were gases.  Mass spectroscopy and gas chromatography indicated
CO,, CO, SOo,  and water as effluent gases.  Infrared spectroscopy showed
the liquid product to be phosphoric acid.  Materials balances indicated that
metaphosphoric  acid was  the probable material from which conversion to
orthophosphoric acid in moist air occurred in 1 to 2 days.

     Analysis for Malathion in the liquid reaction product was carried out
colorimetrically (10).  Percent conversion was 99. 98 + percent based on
0. 016 percent Malathion determined.

5. 2  POLYCHLORINATED BIPHENYLS (PCB'S)

     Monsanto Aroclor 1242 liquid was passed through a 250 Watt oxygen
plasma at 100 torr pressure.   Mass balance weighings showed no liquids
attributable to the starting material.  All the products of decomposition
were gases.  On the basis of control runs in the absence of the plasma
                                  22

-------
           TABLE 2.  REPRESENTATIVE LABORATORY-SCALE OXYGEN PLASMA REACTIONS
Pesticide/
Waste
Malathion
"Cythion" ULV
PCB,
Aroclor 1242
Methyl Bromide
Phenylmercuric
Acetate,
"Troysan" PMA-30
Run No.
28-40
28-58
28-94
28-142
Microwave
Plasma
Power
(W)
200-250
250
300-400
225-280
Pressure
(torr)
100-120
100
50
120
Conversion
99. 98+
99. 9+
99*
99. 9
Reaction Products
S09, C09, CO, H90, HPO,orH,,PO, *
£i £t & «J iJ TT
co2, co, H2o (ci2o, coci2)*
CO2, CO, H2O, Br2, BrO2*
Hg, C02, CO, H20
CO
    See text.

-------
reaction,  percent conversion was  calculated at greater than 99. 9 percent.
Gas products were identified as CO2, CO,  H^O, C12O,  and COC12.  It will
be of interest to note that the latter gases, chlorine oxide and phosgene,
were not observed in the expanded-scale plasma reactions; rather, hydrogen
chloride was the principal Cl-containing product (see section 6. 2).

5. 3 METHYL BROMIDE

    Gaseous methyl bromide was  passed through 300 to 400 Watt oxygen
plasmas at 50 torr pressure at 2 to 3 g/hr.   The products  of reaction were
CO2>  CO, H2O, and Br2>  Oxides  of bromine were found in the liquid nitro-
gen traps, but were not otherwise  produced at ambient temperatures. Quan-
titative analysis of the plasma reactions was performed by mass spectro-
meter,  in which the ratios of CHgBr response heights before and during the
plasma reactions were compared.  (See  Appendix A, Mass Spectra). Con-
ventional analytical methods were  precluded because of the toxicity of the
methyl bromide gas.  Decomposition was greater than 99 percent,  which is
the limit of precision for the method.

5. 4 PHENYLMERCURIC ACETATE

    Commercial  Troysan PMA-30 solution  (30 percent phenylmercuric ace-
tate, approximately 70 percent methyl alcohol, plus ammonium acetate)
was passed through a 225 to 280 Watt plasma at 120 torr pressure.  Metallic
mercury was observed as a metallic mirror on the glass tubing downstream
from the plasma zone.  Material balance indicated   99. 9 percent decompo-
sition to mercury metal.  Mass spectroscopy showed the products formed in
addition to Hg were HoO,  CO2,  and CO.  There was no evidence of dimethyl
mercury or  other organomercurials.
                                 24

-------
                              SECTION 6

    RESULTS OF EXPANDED-SCALE OXYGEN PLASMA REACTIONS

    The expanded-scale plasma system is defined as the equipment shown
in Figures 8 through 11 which resulted in detoxification yields of 450 to
3200 g (1 to 7 Ib) per hr.

    Three microwave  power applicators and three equivalent-size quartz
reactor tubes were used in the evaluations.   During the initial runs, the
Series A 2. 7-liter applicator was used for oxygen plasma decomposition  of
PCB, Aroclor No.  1242.  It was determined that the liquid had been decom-
posed and that one of the reaction products  — a black,  soot-like deposit
which coated the product receiver — contained no PCB, as determined by
infrared spectroscopy. Several additional runs,  in which feed, pressure,
and absorbed power were varied, indicated,  however, that the Series A sys-
tem was too large in volume for the  power available.  As a result, the
Series B and C applicators, 1. 46 and 0. 65 liters, respectively, were used
for all detoxification reactions which are described in the following subsec-
tions, and detailed in Table 3.  It may be readily concluded, from the re-
sults of these evaluations,  that the Series C reactor yielded the highest
throughput, the highest percentage of conversions, and the lowest costs,  as
calculated in Section 6. 6.
6. 1  MALATHION

    "Cythion" Malathion ULV liquid was drop-fed onto a porous, dielectri-
cally heated quartz wool bundle positioned at the top applicator input to the
plasma zone.  By this means, in a similar mechanism to that which was
used in the laboratory-scale system, large numbers of smaller droplets or
vaporized particles were produced within the matrix of the heated wool, and
propelled by the carrier gas through the plasma.  Reaction products were
gaseous sulfur,  803,  H2O,  CO,  COo,  and acetylene,  plus a liquid phos-
phoric acid.  Deposits of a dark yellow-brown sulfur product mixed with a
clear,  water-white high-viscosity liquid dropped gradually down the sides
of the reactor into the receiver.  No carbon or any products resembling the
starting material were observed.  Analysis of the liquids from two  reactions
gave results of 12 ppm and  <1 ppm Malathion,  respectively,  or conversions
of 99. 9988 and 99. 9999 + percent.

6. 2  POLYCHLORINATED BIPHENYLS (PCB'S)

    Runs 31-8,  31-10, and 31-62 yielded HC1,  CO, CO2, and H2O as deter-
mined  by mass spectrometer. No C12O or COC12 was observed.  There


                                  25

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          TABLE 3.  SUMMARY OF EXPANDED-SCALE OXYGEN PLASMA REACTIONS

Pesticide/ Waste
Malathion
"Cythion" ULV
Malathion
"Cythion" ULV
PCB
Aroclor 1242
PCB
Aroclor 1242

PCB
Aroclor 1254
g PMA
TroysanPMA-30
PMA
TroysanPMA-30
PMA
TroysanPMA-30
Kepone 80/20
20% Methanol
Solution
Kepone 80/20
10% Solids
Aqueous Slurry
Kepone
2- to 3-g
Solid Discs
	
Run No.
31-16

31-46

31-8

31-10


31-62

31-88
31-108
31-110
38-30


38-36


38-38



Reactor
Series
B

B

B

B


B

C
C
C
C


C


C


Microwave
Power
(kW)
3. 7

4.7

4.6

4.2


4.5

4.6
4.0
4.3
4.6


4.2


4.6


Feed Rate
g/hr
(lb/hr)
504(1. 1)
:
480(1. 1)

270(0. 6)

Pressure
(torr)
28-46

28-30

17-35
i
492(1. 1)


206(0.4)

1020(2. 25)
2380(5. 25)
2950(6. 5)
(a)


_


-


19-36


13-25

120-140
100-120
100-120
54


40


7


Oxygen
Gas Flow
(liters /hr)
361

480

323

395


360

960
792
792
720


None


90



Reactor
Packing
Wool.
Plug (a>
Wool
Plug
Wool

Wool
TDIll rt
.Plug
Solid
Rings (a)
Raschig
Rings (a)
Raschig
Rings
Raschig
Rings
Raschig
Rings
o
Raschig
Rings

Raschig
Rings


Conversion
99. 9988

99. 9999

99

99


99

Complete
estim, 99. 99^
Complete
estim. 99. 99
Complete
estim. 99. 99
99


99


99


(a) Quartz    (b) see text

-------
was formation of soot in the product receiver; infrared analysis gave no
indication of PCB residues.  It was determined, however, that at throughput
levels of about 1  kg/hr in the B reactor, complete reactions had not occurred.
This was determined by infrared analysis of the black tar-like liquid products
in the receiver trap which indicated the presence of PCB starting material.

6. 3 PHENYLMERCURIC ACETATE

    Troysan PMA-30 was passed through the Series C reactor in several
runs to  determine the effect of the shortened length of the reactor, and the
presence of quartz Raschig rings in the reactor tube.  The  reaction was con-
sidered complete; i. e., no starting material passed through the plasma zone,
if methanol peaks were not found by mass spectroscopy in the effluent gas.

    A series of reactions showed that at a throughput of 3600 g/hr (8 Ib/hr),
small amounts of methanol solvent were detected in the gaseous  effluent.
This indicated that under the conditions of this series,  between 7 and 8 Ib/hr
can be considered for effectively complete detoxification/destruction of
PMA-30.   The principal gases of the reaction were CC>2, CO,  and H2O.
Metallic mercury was deposited in the traps downstream from the plasma.
Additional information is given in subsection 7. 2. 4.  It is also of importance
to note that no organomercurials were detected by the mass spectrometer.

6.4 KEPONE  -  A "REAL WORLD"  MIXTURE

    A commercial, clay-supported mixture, Allied Chemical 80-percent
Kepone  concentrate, Code 9406,  was used for all tests.  Approximately
250 g was available, which was  converted as needed into water slurries,
methanol,  and methanol/acetone solutions,  and solid press cakes.  The solid
press cakes were prepared by compressing 2-3 g batches of Kepone 80/20
in a die under 1000 psi pressure.  The discs, which required strong finger
pressure to fracture, were placed at the top of the Raschig ring area in the
plasma reactor tube before the plasma was ignited.  It was observed visual-
ly that breakdown of the solids occurred in  10 to 30 seconds, depending on
the flow of oxygen and the pressure within the reactor.  An extrapolation of
a 3-gram batch decomposition in 15 seconds yields 720 g/hr or 1. 6 Ib/hr
detoxified.  The gaseous reaction products  were CO2,  CO,  HC1,  and H2O.
Hexachlorobenzene, phosgene, or chlorinated hydrocarbons were not detec-
ted using a combination of techniques involving infrared and mass spectros-
copy.  Because of the limited quantity of the starting material, the reac-
tions were not optimized with respect to throughput.  Nevertheless,  3 kg/hr
(7 Ib/hr) are considered to be well within the capabilities of the system.
Safety and handling precautions were observed meticulously for the Kepone
experiments.  All  solution and dispersion operations were  carried out in a
chemical hood which had a linear velocity of 100 feet per minute at the air
inlet.  Press cake operations performed in the open laboratory utilized a
4-in. -diameter suction tube which was connected to the chemical hood.  The
tube acted as a vacuum cleaner-type device to prevent dust from contaminat-
ing the  laboratory  area; and decontamination of residual solids were carried
out by dissolving in acetone which was subsequently stored in separate  waste
bottles. Paper wipes were also stored separately.
                                   27

-------
6. 5 STEAM PLASMA DETOXIFICATION OF PMA-30

    Toward completion of the program, several successful exploratory
experiments using steam instead of oxygen were performed in the expanded-
scale Series C plasma unit.  PMA-30 was evaluated in this  reactor.

    The major products of the discharge were COo, CO,  H2O and mercury
metal.  Very few, if any,  signs of lower (Cj to C<£) hydrocarbons were ob-
served.  There was also no sign of the PMA methanol solvent.   Thus, the
water plasma  decomposition of PMA appeared the  same as that which oc-
curred in the oxygen plasma.

    Because of the potential for significant cost savings and the fact that
steam,  when condensed, will develop its own vacuum, this additional tech-
nology is  considered to be of significant promise.  In addition,  when the
water vapors condense below the plasma zone,  dissolution or entrapment of
acid gases can occur. The dissolved materials may then  be treated with
caustic by standard  methods.  It is therefore planned to include steam as
carrier gas in future microwave plasma investigations at  the pilot- and
demonstration-levels.

6. 6 PROCESS COSTS CALCULATED FOR PMA-30

    For the initial detoxifications in the expanded-scale plasma system,  a
cents-per-pound figure for electrical power and carrier gas costs was cal-
culated.  It was considered appropriate that the calculation be made exclu-
sive of capital investment  for later comparison with pyrolysis,  high tempera-
ture,  and other forms of specialty incineration as  data on those processes
became available.  This type of information was derived for the conversion
of phenylmercuric acetate pesticide. It is presented in  Table 4.

    For the determination of process costs  for future 50 to  100 Ib/hr demon-
stration-scale plasma systems, an accurate assessment is  at this time
replete with difficulties.  Nevertheless, where the object  is to  show,  in
principle,  the economic viability of the approach,  it is possible to calculate
values which can be  derived from known process variables and estimated
carrier gas, electrical,  and related  costs.

    The material  chosen for the  calculation was phenylmercuric acetate
(PMA),  first,  because it was considered refractory or difficult to decompose
completely and, second,  because it has the significant advantage of recover-
ability of its metallic mercury values.

    The following assumptions are listed below as part  of the estimated
costs:

    (1)  Electrical costs are $0. 012/kWh,  industrial usage.

    (2)  Liquid oxygen costs are $0.005/SCF, large volume usage.
        Add $3000/yr storage  fee.
                                  28

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          TABLE 4.  ELECTRICAL AND CARRIER GAS COSTS FOR PLASMA REACTIONS IN
                         SERIES C REACTOR EXPANDED-SCALE SYSTEM



Run No.
31-88
31-108
31-110



Material
PMA-30
PMA-30
PMA- 30



Carrier
Gas(a>
°2
°2
°2
Effective
(Absorbed)
Microwave
Power
(kW)
4.6
4.0
4. 3


Feed Rate
[g/hr
(lb/hr)]
1020(2.25)
2380(5. 25)
2950(6. 5)

Carrier Gas
Flow
[std liter/hr
(SCFH)]
960(34)
792(28)
792(28)



Gas Cost
($/lb)
0. 18
0.064
0.054

Total
Power
Consumed
(kWh/lb)
4.7
1.9
1.6


Power
Cost
($/lb)(b>
0.06
0.023
0.019



Total Cost
($/lb)
0. 24
0.087
0.07
tO
CO
    (a)  02,  $0.012/ft3

    (b)  kWh, $0.012,  Industrial Usage.

-------
    (3)  Steam costs are $2. 00/1000 Ib.

    (4)  Labor costs are one-half man per automated unit, i. e.,  one man
         operates two units,  $12/hr.

    (5)  In the case of PMA, the credit for metallic mercury is $1. 50/lb.
         This is based on a requirement for future purification.  At present,
         the purity  of the recovered metal has not been determined.  A more
         pure product obviously has greater value, up to $4/lb.

    (6)  The estimate for capital costs is  $100, 000.

    It  may appear at this time that 50 to 100 Ib/hr are low values when
compared with municipal waste processes.  However, the detoxification of
even a small, 10-pound batch of a highly toxic or dangerous substance can
give great concern  to those who are responsible for its safe disposal.

    In the following calculation, a standard 330-day/year,  three-shift
operation is assumed.  PMA-30 throughput is 50 Ib/hr,  or 400, 000 Ib/yr.
The process  costs related to PMA-30 on a per-pound basis are as follows:

    •    Oxygen      4. 3 SCF

    •    Steam       1. 5 Ib

    •    Electrical    1. 6 kWh

    Calculated total process costs are listed below:

                                                 Oxygen         Steam

    Variable Costs

       Operating Labor                         $ 47, 520     $ 47, 520

       Maintenance  (4% of Investment)              4, 000         4, 000

       Oxygen or Steam                           11, 600         1, 200

       Electricity                                  7, 680         7, 680

                  Total Variable Costs          $ 70, 800     $ 60,400

    Fixed Costs

       Taxes and Insurance (2%/yr)              $  2,000     $  2,000

       Capital Recovery (10 yr - 10%)              16, 250       16, 250

                  Total Fixed Costs             $ 18,250      $ 18,250
                                  30

-------
                                                 Oxygen          Steam

    Total Annual Costs                          $ 89, 050        $ 78, 650

    Total Income From Recovered Mercury      $108,000        $108,000

                   Total Net Profit               $ 18,950        $ 29,350

    Net Profit Per Pound Treated               $   0.047        $  0.073


    For detoxification of materials,  such as Malathion  or polychlorinated
biphenyl wastes, where little or no useful by-products are recoverable, the
costs may be higher.  In oxygen and steam plasmas, for example, the costs
per pound are calculated as $0. 22 and $0. 20,  respectively.

    It should be noted that as microwave power technology advances, the
electrical costs should decrease as the result of improvements in the coup-
ling of microwave power to the plasma reactors.  The potential for steam
plasmas with their low cost, plus their capability to form their own vacuum,
is readily apparent, and can therefore be considered for further reductions
in electrical power requirements.

    The above data have been  derived for a permanent-type disposal center,
which may then be  compared with other methods operating at similar levels
of throughput.  The costs associated with projected mobile, or back-of-truck
type,  detoxification units will vary,  depending on the initial capital costs,
which should be lower, and labor  costs,  which may be higher per unit.  The
latter will be dependent in part on the distance to the user's site as well as
the toxicity of the materials to be treated.
                                    31

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                              SECTION 7

                       DISCUSSION OF RESULTS

    An overview of the chemistry of microwave plasma detoxification and
process variables as determined during the first year of the program is
presented in the following subsections.


7. 1 INTERPRETATION

    •  Microwave detoxification, using oxygen plasmas, has been success-
       ful and practical for all pesticides and hazardous wastes tested to
       date. These include Malathion, polychlorinated biphenyls, methyl-
       bromide gas,  phenylmercuric acetate, and Kepone.

    •  Optimization of plasma conditions was performed for the refractory
       organomercurial,  phenylmercuric acetate. As a result of varying
       the several parameters affecting the detoxification efficiency, decom-
       position was  3. 2 kg/hr (7 Ib/hr), yielding  principally gaseous CO2,
       CO,  H^O, and metallic mercury.  The mercury has a known cost
       recovery value, thereby resulting in low or nonexistent operating
       costs for that particular material.

    •  Oxygen plasma reactions were uniform in  their production of gaseous
       oxides of carbon, water, and acidic gases.

    •  Pure liquids,  solutions,  aqueous slurries, and powders as press
       cakes were decomposed by oxygen plasmas.   The only differences in
       response were associated with the methods of addition used for the
       respective materials.  The chemical reactions were effectively iden-
       tical.

    •  Further process cost reductions are potentially feasible through the
       use of steam plasmas, which, in addition to low costs relative to
       oxygen,  can also develop their own reduced pressures in the plasma
       reactor.
                                   32

-------
7. 2 CHEMISTRY OF OXYGEN PLASMA REACTIONS

7. 2. 1  Malathion — Oxygen Plasma Reactions

    Complete oxidation of Malathion in the laboratory- scale system yielded
colorless gases  and a water-white liquid:  SO2, CO2, CO,  HoO, and phos-
phoric acid products.   Several equations may be written for the reactions.
For simplicity,  only CO2 is included,
C10H19°6PS2 + 15O2~^2SO2 + 10CO2 + 8H2° + H3PO4 (°rth°PhosPhoric acid)

C10H19°6PS2 + 15O2-*2SO2 + 10CO2 + 9H2° + HPO3 (metaPhosPhoric acid)

2C10H19°6PS2 + 30O2~~4SO2 + 20CO2 + 17H2° + H4P2°7 (pyr°PhosPhoric acid>

2C10HigOgPS2 + 30O2— 4SO2 + 20CO2 + 19H2O + P2°5 (phosphoric anhydride)

    Starting with 2. 7 g Malathion added, the stoichiometry indicates the
following:

                         H3P04      0. 80 g

                         H4P20?      0. 73 g

                         HPO3       0. 65 g

                         P205        0. 58 g

    The experimentally determined value, twice run,  was 0. 66 g.   Although
pyrophosphoric acid has been detected in air- oxidation incineration reac-
tions  of phosphorus -containing materials, metaphosphoric acid appears to
have been produced in this system.  The difference in phosphoric acid iden-
tities may be related to the differences in the effective temperatures of the
two reactions, and,  consequently, their rates of formation in air (incinera-
tion) versus pure oxygen (plasma process).   On further exposure of the
phosphoric  acid liquid to laboratory air for several days,  orthophosphoric
acid was determined by infrared spectres copy to be the final product.

    In the expanded- scale Series B system, some sulfur and small amounts
of acetylene were observed in addition to CO2, CO, H2O,  and SO2.   This is
attributed to the incomplete oxidation of the starting material, since the  sys-
tem had not yet been optimized.  It would not be considered difficult now to
obviate acetylene or sulfur under currently optimized conditions in the
Series C reactor.

7. 2. 2 PCB - Oxygen Plasma Reactions

     Reactions in the laboratory- scale system yielded CO2, CO,  I^O, C^O,
and COC12, whereas in the  expanded- scale  system, Series B, no C^O or
COC12 was observed.  Instead, HC1 was the Cl-bearing product detected,
plus a soot-like deposit in the product receiver.   It is probable that the
                                    33

-------
 following type of reaction occurred in the reactor configuration used at the
 time:

        C12H?C13 + 11/2O2 — 2H2O + 3CO2 + SCO + 6C(soot) + 3HC1

 Optimization of the reaction in the Series C reactor should result in the dis-
 appearance of soot,  and an additional formation of CO2, etc.

 7. 2. 3  Methyl Bromide —  Oxygen Plasma Reaction

     In the laboratory-scale system, oxidation yielded CC>2,  CO, H2O, and
 Br2 as principal products, with some BrO2 and/or Br2O formed inside the
 liquid nitrogen traps.  The principal reaction may be written as follows:

                  4CHgBr + 7O2 — 2Brg + 4CO2 + SHgO

 Side reactions involving Br2 and H2O may have produced HBr and HOBr.

 7. 2. 4  Phenylmercuric Acetate  — Oxygen Plasma Reactions

     In both the lab oratory-scale and expanded-scale plasma systems, the
 major products  were CO2,  CO,  H2O, and mercury metal.  Minor amounts
 of lower molecular weight hydrocarbons were observed in the expanded-
 scale system.  The formation of metallic  mercury may be explained by
 postulating HgO as an intermediate in the  plasma reaction, followed by its
 decomposition.  The dissociation pressure of HgO to give  Hg metal  and O2
 is a few torr at  440°C (11).  Thus, Hg metal can be produced as follows:

             1)  C8H802Hg + 19/202 -HgO

                     400-500°C
             2)  HgO	"    Hg+ 1/202

 Addition of 1) and 2) yields:

                  C8H802Hg + 902 - Hg + 8C02

 Oxidation  of methanol is considered to follow the usual mechanism to CO2
 and H2O,  depending on the quantity of oxygen available.

 7. 2. 5 Kepone — Oxygen Plasma Reactions

    The plasma reaction products of 20 percent Kepone-methanol and
Kepone-methanol/acetone solutions in the  expanded-scale  system were COo,
 CO,  H2O,  and HC1.  Hexachlorobenzene,  phosgene,  or chlorinated hydro-
 carbons were not detected.   Reactions in an oxygen plasma may therefore
be written:


                 C10C110° + 7°2 ~* 5C02 + 5CO + 5C12
                                 34

-------
                  2CH-OH + O0 — CO + CO0 + H0O                    (2)
                     •j       &           &    &

Reaction of Cl2 with the H2O from the methanol reaction produces HC1 and
HC1O; since the latter is unstable, it decomposes to HC1 and oxygen.

    It is of interest to note that the time periods for decomposition of small
3 g,  80/20 Kepone press cakes within the plasma zone were 10 to 30 sec;
the actual values  depended on the surface area of the solids,  the flow of oxy-
gen,  and the pressure within the reactor.

    Percentage conversions  are listed at >99 percent.  The values are
based on analysis of the effluent products. Absence of Kepone or hexachloro-
benzene in the receiver,  or any low  molecular weight chlorinated hydrocar-
bons in the gas effluent denotes a greater than 99 percent conversion. Infra-
red spectrograms of Kepone  extracted with acetone and its oxygen plasma
reaction product are shown in Figure 13.

7. 3  EVALUATION OF ANCILLARY EQUIPMENT

    Four specific unit processes were developed and tested for use in the
expanded-scale plasma detoxification system,  as follows:

    •  Materials feed techniques

    •  Packed bed technology

    •  Reduced pressure systems

    •  Analytical processes

7. 3. 1 Materials  Feed Techniques

    Several techniques were evaluated to optimize as far as  practicable the
desired materials introduction processes. These included one- and two-
fluid spray nozzles, in which the feed stock was introduced upwards from
bottom to top in order to maximize residence time and to minimize gravity
effects.  No fine-spray system was found  completely satisfactory, since
little or no liquid spray flare-out can be tolerated below the plasma zone in
the waveguide cutoff. If Hare-out is permitted, thermal decomposition may
occur in the cutoff, and the chemical identity of the products as well as the
material balance  becomes difficult or impossible to evaluate.  Custom-
fabricated two-fluid nozzles  are now being designed to avoid these problems,
which .can become more significant when  larger quantities of materials are
detoxified.

    The most successful technique was a vacuum-equalized liquid-feed sys-
tem  (Figure 12) into which several Teflon needle valves  were constructed
for improved drop-size control.  This technique was used for gravity feed-
ing PCBs and PMA-30 solutions.  For feeding Kepone solutions and water
slurries,  the use of a volumetric buret was adequate; the feed was kept at
                                   35

-------
25
                                                   WAVELENGTH (M)

                                                      6        7
                                                                     8     9  10    12     15    20    30 4050
  100
  60

                                                                    '
                                                                               .-
u
  40
  20
                                                             3

   4000      3500      3000      2500      2000     1800     1600    1400    1200     1000     800     600
                                                   WAVENUMBER (CM~')
                                                                                                      200
          Figure 13.  Infrared spectra of Kepone acetone extract (curve A) and its  oxygen
                       plasma reaction product (curve B)

-------
atmospheric pressure to avoid continual depletion of solvent during the addi-
tion.  Only the buret tip, inserted into the reactor above the plasma zone,
was maintained at reduced pressure.

    Feed techniques for solids are also under investigation.  These include
a two-tier reduced pressure forechamber in which the solids are placed.
The solids will be fed  into a kiln-type,  angularly-positioned reactor which
is rotated by means of a suitable, motorized transport.

7. 3. 2  Packed Bed Technology

    Quartz  Raschig rings were used in the reactor tube in order to increase
the residence time of the feed materials in the plasma zone.  Several varia-
tions in ring size and bed length  were evaluated to determine maximum
throughput under different packed bed conditions.  Maximum throughput was
defined as that quantity passing through the reactor which showed no metha-
nol solvent in the mass spectrometer scans.  Data are listed in Table 5.
Without rings, decreased detoxification levels were observed because of ex-
cessively short,  0. 1  sec,  residence times.

    On the basis of these runs, the application of packed bed technology can
be considered for use where aqueous solution, pure liquids, and solvent sys-
tems are to be treated.  Ring materials may be quartz or high-alumina ce-
ramics which are not  "lossy", i. e. ,  do not show high dielectric loss factors,
and thus do  not "heat up" at 2450 MHz, which is  the microwave frequency
used in the process.  In the batch detoxification  of Kepone solids, the packed
bed approach was used successfully.  For the continuous feed of solids and
powders into beds of the above geometry,  further investigation will be re-
quired for development of the technique.

7. 3. 3  Reduced Pressure Systems

    Sargent-Welch 1397B Duo Seal mechanical vacuum pumps (approximate-
ly 400 liters/min pump capacity) were used for the development of the re-
duced pressure required for plasma formation.  Liquid nitrogen,  ice, or
mixed ice-acetone traps were used,  depending on the materials being stud-
ied,  to trap out materials which would otherwise react with the oil or metal
parts.  This design has been adequate for the  initial Phase I scale-up opera-
tion.   However,  it is likely that  at the next level of scale-up more practical
pump systems will be required,  such as liquid ring seal or steam ejector
pumps.  These will obviate in large part the need for traps,  which require
filling,  cleaning,  etc. , and can serve as a transfer medium for moving the
acid gas products to a caustic scrubber for later disposal  into municipal
waste  streams.

7. 3. 4  Analytical Processes

    The  methods used in  this study have been described above.  (See Sec-
tion 3. 3 and  Appendix A. ) The  principal  objective has been to  deter-
mine  the levels of detoxification/decomposition  achieved in the expanded-
scale  plasma system, thereby evaluating the potential  usefulness  of
                                   37

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       TABLE 5.  INFLUENCE OF PACKED BED ON PMA-30(PHENYLMERCURIC ACETATE)
                          CONVERSION IN SERIES C PLASMA SYSTEM
Run No.
31-88



31-108

31-110
38-6
38-8

,
38-14




Packing of 45-mm Reactor
Ring Size
o. d. x Length
(mm)
8x8



8x8

8x8
10 x 10
8x4


8x8




Bed
Length
(cm)
16



45

45
34
31


31




Gas
Flow
(Standard
liter/ min]
8 to 16



13. 2

1 3 , 2
13.2
13.2
to
18.4
13.2
to
16.0


Pressure
(torr)
Top
120



120

120
115
112


130




Bottom
-



64

60
42
60


75




Absorbed
Power
(kW)
4.7



4.0

4. 3
4. 3
4.6


4. 7




Throughput
(lb/hr)
2.25



5. 25

6. 5
4.25
6.0


8.0
5.4



Notes
First high throughput
run; reactor filled
approximately one-
half with rings
Reactor completely
filled with rings
Repeat of 31-108
Largest rings of series
Rings fused near bot-
tom port of power
input
CH~3OH solvent ob-
served at 8 lb/hr;
disappeared when
rate decreased to
5. 4 lb/hr
oo

-------
the process.   The methods adequately served this purpose.  It will be neces-
sary in further process developments, however,  to refine the analytical
techniques whereby in situ determination of ppm  reaction products can be
obtained.   This will be required for analysis of gaseous as well as liquid
(water, steam) effluents,  before these streams can be disposed of into muni-
cipal sewage streams or  directly to the air environment.

    In line with these requirements,  high-sensitivity gas chromatograph
units with  appropriate detectors are required for in-line determination of
impurities, if such exist.   Improvements in mass spectroscopy, and, later,
installation of a gas chromatograph-mass spectrometer plus computer scan
and readout of pesticides and toxic materials,  can be a significant aid in
assessing  the completeness of the oxygen/steam  plasma reactions,  and
thereby its usefulness as a detoxification method.
                                    39

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                               SECTION 8

                             CONCLUSIONS

     1.   The process of microwave plasma decomposition of organic mate-
rials has been applied successfully to the detoxification/destruction of
hazardous organic wastes.  A primary objective of the program -  evalua-
tion of the effectiveness of an expanded-scale plasma system  -  has been
completed using hazardous organic compounds and wastes of current inter-
est. The reaction products were identified in order to estimate their toxi-
city and  to determine the potential for recycling/recovery of useful by-
product materials.

     2.   This program has resulted in an expansion of  the state of the art
in microwave plasma detoxification from 1  to 5 g to 3 kg (7 Ib) per hour.
One hundred fifteen (115) runs were performed in the series.  This scale-up
has changed the perspective from one of academic interest to that of a real-
istic or practical level.

     3.   The commercial pesticides, Kepone, Malathion,  phenylmercurie
acetate,  and methyl bromide; and the hazardous  waste, polychlorinated bi-
phenyl, can be  detoxified beyond 99 percent in an oxygen plasma system.
Malathion in pure liquid form was decomposed to > 99. 999 percent and
liquid PCB to at least  99. 9 percent.

     4.   The potential for resource recovery has been  clearly demonstrated
for PMA-30, phenylmercuric acetate solution.  The commercial form of
this organomercurial was decomposed efficiently to yield metallic mercury,
which is  a salable item, plus  oxides of carbon and water.  The process may
permit the  additional recovery of valuable chemical feedstocks when applied
to other  organometallic pesticides or wastes which would otherwise be per-
manently lost.

     5.   The process itself is eminently safe.  Microwave leakage is not
detected near the applicator or the  power supplies.  Because reduced pres-
sures (low vacuum) are used, the equipment,  by its nature,  does not permit
materials loss  through buildup of excess pressures and the consequent pres-
sure blowoffs.  Further, dangerous leaks will not occur, because the plasma
unit would first shut itself down, and,  simultaneously,  terminate by means
of interlocks, the introduction of feed materials.  Process controls have not
been complex in the initial scale-up development, but high sensitivity toxi-
city monitors at the ppm level will  be required as the size of the equipment
increases.
                                   40

-------
    6.   When compared with refractory incinerators, the microwave plasma
systems have several advantages,  such as potential for portability,  or  back-
of-truck transport to a  toxic materials' site, relatively low initial cost, leak-
proof character,  and, thus,  the capacity for decomposing materials where
no other techniques are satisfactory.  For example, in an  ordinary inciner-
ator,  the decomposition of phenylmercuric acetate, or any organomercurial
waste, would result,  unless all openings were totally closed,  in an uncon-
trolled release into the environment of mercury metal or oxide particles.
In the plasma system, the mercury is separated from the effluent gas stream
and collected.

    7.   Since the plasma decomposition mechanism utilizes electronic ener-
gy, in which the applicator  can be maintained barely hot to the touch, rather
than thermal energy, materials-of-construction requirements are signifi-
cantly less stringent.  This  results in lower materials costs, which reduces
maintenance and  repair expenses.
                                   41

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                               SECTION 9

                         RECOMMENDATIONS

    This study, Phase I,  Development of Microwave Plasma Detoxification
Process, unquestionably points toward a phased,  logical scale-up to a
20 Ib/hr unit,  and then to a 100 Ib/hr version.  A program,  as outlined be-
low, is recommended  for the design, purchase, and construction of pilot-
scale equipment and components.  For development of the system, denoted
as Phase II, specific engineering tasks are suggested.

    •  Materials Feed Operations.  Techniques need  to be developed and
       evaluated for the feeding of materials to be detoxified into the
       plasma reactor.  These materials may be gases, liquids, solids,
       or slurries.  The problem should be defined in detail,  and the
       necessary equipment designed,  installed,  and  tested in accordance
       with data obtained from the program recently completed.

    •  Microwave Power.   Additional microwave power, above  5 kW at
       2450, is suggested for the  pilot process in order to expand capacity
       to the desired 20 Ib/hr or more throughput.  Power-generating
       components and ancillary equipment are purchasable off  the shelf
       from, microwave hardware suppliers.

    •  Microwave Plasma Applicator/Reactor. A new high-power appli-
       cator is needed for transfer of the increased microwave  energy
       to the plasma reactor.  The applicator is available as a custom-
       fabricated unit. The reactor materials suggested for use are
       catalog items.

    •  Product Receptor.  For  plasma reactions  which involve in parti-
       cular the formation of metals,  cooling traps/heat exchangers
       should  be designed  and evaluated for product separation and con-
       densation.

    •  Vacuum System.  High-capacity liquid ring pumps should be evalu-
       ated for obtaining reduced pressures,  based,  in part, on their
       capability for acting as a medium for dissolving many of the acid
       products emitted from the reactor.

    •  Analytical Instrumentation.  Process effluents should be analyzed
       for  traces of potentially  toxic impurities,  if any of these materials
       are  formed.  Gas chromatographic units,  infrared and ultraviolet
       spectrophotometers,  and a quadrupole residual gas analyzer
                                  42

-------
       (mass spectrometer) should be installed in-line for obtaining the
       required data.

    It is also recommended that side-support studies be continued at the
basic scientific level for evaluation of variables,  such as microwave fre-
quency and applicator/reactor technology to determine their potential ef-
fect on maximum size and throughput.

    In conclusion,  continued exploration of detoxification of "new" hazard-
ous wastes should be maintained.  In this regard,  more than a hundred
requests for information and data have been received during the last several
months.  These involved toxic waste and waste-related problems not pre-
viously considered for this application,  thus indicating clearly the wide
interest this new technology has engendered.
                                   43

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                             REFERENCES

 1.   McTaggart,  F.  K.,  Plasma Chemistry in Electrical Discharges, Else-
     vier, Amsterdam, 1967, p.  2.

 2.   Lockheed Missiles & Space Company, Inc.,  Dissociation of Toxic Gas
     Analogs in an Electrical Discharge,  Lockheed Independent Research
     Program,  Apr 1969.

 3.   Sibert, M. E.,  Vapor Decomposition by Microwave Discharge, Con-
     tract DAAA  15-70-C-04880, Final Report, LMSC-D243400, Sep 1971.

 4.   Bailin, L. J. ,  M. E.  Sibert, L. A.  Jonas, and A. T.  Bell, "Micro-
     wave Detoxification  of Toxic Vapor Simulants, " Environmental Science
     and Technology,  9 (3),  254-58,  1975.

 5.   Bailin, L. J.,  "Cold Plasma Detoxification of Toxic Wastes, " Water
     Quality Treatment,  Final Report LMSC-D356581, Lockheed Independent
     Development Program,  Dec 1973.

 6.   MacDonald,  A.  D. ,  Microwave Breakdown in Gases, John Wiley, New
     York,  1966,  p.  71.

 7.   Fehsenfeld,  F.  C.,  K. M. Evenson,  and H.  P. Broida, "Microwave
     Discharge Cavities Operating at 2450 MHz, " The Review of Scientific
     Instruments, 36_(3),  294-8,  1965.

 8.   Bell, Alex. T., in "Techniques and Application of Plasma Chemistry, "
     John R.  Hollahan  and Alexis T. Bell, Ed., Chapter 10, Engineering
     and Economic Aspects of Plasma Chemistry, John Wiley,  New York
     1975, pp. 379-381.

 9.   Brown, Lloyd C., Alex. T.  Bell, "Kinetics  of the Oxidation of Carbon
     Monoxide in  a Radiofrequency Electrical Discharge, " Industrial Engin-
     eering Chemistry, Fundamentals, 13, 203, 1974.

10.   Norris,  M. V., W.  A. Vail and P. R.  Averell,  "Colorimetric Estima-
     tion of Malathion Residues, "Agricultural  and Food  Chemistry, 2 (11),
     570-73,  1954.

11.   Remy, H., Treatise of Inorganic Chemistry,  Vol.  II,  Elsevier,
     Amsterdam,  1956, p.  464.

12.   Brooks,  G. T., Chlorinated Insecticides,  Vol.  1, CRC Press, Cleve-
     land, 1974,  pp.  97-104.

13.   Safe, S.  and  O.  Hutzinger,  Mass Spectroscopy of Pesticides and Pollu-
     tants,  CRC Press, Cleveland, 1973,  pp.  28,  195.
                                   44

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                              Appendix A

                            MASS SPECTRA
A. 1  EQUIPMENT
    A quadrupole mass spectrometer Varian Model 974-0002 residual gas
analyzer was used to analyze the effluent gases from the reactor, as fol-
lows. A small quantity of gas leaving the plasma reactor is pumped past a
variable-leak sampling valve which is located approximately 6 meters from
the plasma exhaust.  Figure A-l is a schematic of the sampling valve inter-
face with the plasma reactor and the  residual gas analyzer.  The sampling
system consists of a quadrupole gas analyzer tube,  a  high-vacuum system
for the analyzer tube,  and a gas admittance system. A fraction of the plasma
effluent gas is bled into the mass spectrometer, and is continually pumped
through the sampling system by a second vacuum pump.  Some of the  gas is
ionized by an electron beam ionizer in the analyzer section of the mass
spectrometer.  These gases not only form parent ions of the same mass as
the neutral molecules, but also dissociate to form smaller ions.  The ions
are separated by mass by the quadrupole mass filter,   and detected by an
electron multiplier.  The electron multiplier generates an electrical signal
that is amplified and recorded. The filter is adjusted  so that it passes ions
of only one mass at a time.  By controlling the filter,   the distribution of
ions is determined, yielding the mass spectrum of the gases present  in the
ionizer,  up to a maximum of 250 mass units.  Figures A-2 and A-3 are
photographs of the  residual gas analyzer hardware and electronics.

     It should be noted, in a mass spectrometer system that is pumped to
10-10 atm,  that there remain approximately  109 molecules/cm^.  A sensi-
tive mass spectrometer will register these background gases as background
ions.

     Vacuum pumps, particularly ion-getter or "Vac Ion" types,  when used
to maintain these low pressures,  do  not pump all gases with equal efficien-
cy.  Certain gases, e. g., argon,  helium, etc., are pumped very slowly
out of the mass spectrometer.  This is the principal reason for the pres-
ence of one of the main residual background gases, argon, which produces
the Ar+ ion,  mass/charge M/E =  40, and the Ar++ ion, M/E =  20.

     It should also be noted that,  because of the dissimilar mass spectro-
meter response characteristics of the different gases within a mixture,
quantitative comparisons using their relative peak heights are not reliable,
and should not therefore be attempted.
                                   45

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               ABSOLUTE
               MANOMETER
SAMPLING
LINE
FROM
PLASMA
REACTOR
SAMPLING
VALVE
                       ULTRA-HIGH
                       VACUUM SYSTEM
                           LEAK
                           VALVE
                     'ROUGHING
                      VALVE
               LIQUID
               NITROGEN
               TRAP
ANALYZER
TUBE
                             VAC ION
                             PUMP
         ISOLATION
         VALVE
              MECHANICAL
              PUMP
   Figure A-l.
    Gas sampling system interface with plasma reactor
    and residual gas analyzer
                              46

-------
--
                                                                     VAC ION PUMP
                                                                     (TITANIUM GETTER)
                                                                        THERMOCOUPLE VACUUM GAGE
                                                                                           X-Y
                                                                                           RECORDER
                                                                                                 I
GAS INLET
VALVE FROM
PLASMA
SYSTEM
                                                                               QUADRUPOLE
                                                                               HEAD
                                                              TOP OF OIL DIFFUSION
                                                              PUMP
                                    •GAS SAMPLING
                                     VARIABLE LEAK
                                     VALVE
      Figure A-2.   Mass spectrometer residual gas analyzer -- variable leak valve and quadrupole head

-------
                                  OSCILLOSCOPE
                                     RESIDUAL GAS
                                     ANALYZER CONTROL
                                     UNIT
=1    \f:
^-DIGITAL
  VOLTMETER
                                       ION PUMP
                                    CONTROL UNIT
                                     ELECTRON MULTIPLER
                                     POWER SUPPLY
                                     IONIZATION GAGE
                                     FOR DIFFUSION PUMP
                                     VACUUM
                                       .A. POWER SUPPLY
       Figure A-3.  Mass spectrometer residual gas analyzer
                  power supplies and vacuum gages
                            48

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A. 2  PESTICIDE AND HAZARDOUS WASTE SPECTRA

    In the following spectra (Figures A-4 through A-10) are shown the
masses of ions derived from the products of the respective oxygen and
steam  plasma reactions.  These include scans from Malathion, PCB's,
methyl bromide,  phenylmercuric acetate, and Kepone.  A brief commen-
tary for each spectrum is included.

A. 2. 1  Malathion —  Oxygen Plasma (Figure A-4)

    The main gaseous products were carbon dioxide (M/E  = 44, 28,  22, 16,
14, 12), carbon monoxide (M/E = 28, 16, 14,  12), water (M/E =  18, 17,16),
sulfur  dioxide (M/E - 64, 48,  32), and, possibly,  a  small amount of ace-
tylene  (M/E = 26,  25).  Most of the ions appearing in the oxygen plasma back-
ground were those formed from the residual background gases, such as
argon  (M/E = 40, 20),  that are always present in the mass spectrometer.

A. 2. 2  Aroclor No. 1242 PCB - Oxygen Plasma (Figure A-5)

    During the run,  most of the oxygen was consumed. The main gases
observed were carbon  dioxide (M/E  = 44, 28,  22,  16,  14,  12), carbon  mon-
oxide  (M/E = 28, 16,  14, 12), and water (M/E =  18, 17,  16).  Chlorine, Cl2,
(M/E  = 70, 72,  74) was not observed, but gaseous hydrochloric acid (M/E~=
35, 36, 37, 38) was detected.  Most of the ions observed in the oxygen
plasma background were those formed from residual background gases, such
as argon (M/E = 40,  20), which are always present in the mass spectrometer.

A. 2. 3  Aroclor No. 1254 PCB - Oxygen Plasma (Figure A-6)

    The main gases observed were carbon dioxide (M/E = 44, 28, 22,  16,
14, 12), carbon monoxide (M/E  = 28, 16, 14, 12), and hydrochloric acid
(M/E  = 35, 36,  37, 38).  Chlorine, Cl2,  (M/E = 70,  72, 74),  was not  ob-
served.  No appreciable amounts of water (M/E =18, 17, 1 6) were observed;
evidently,  the hydrogen present in the Ci 2^05  molecules reacted to form
hydrochloric acid HC1 preferentially.  There appeared to be excess oxygen
(M/E  = 32) present for these reactions.  Most of  the ions formed in the oxy-
gen plasma background were those formed from residual background gases,
such as argon (M/E = 40, 20), that are  always present in the mass spectro-
meter.

A. 2.4  Methyl Bromide  — Oxygen Plasma, Laboratory-Scale Reactor,
       Quantitative Analysis (Figure A-7)                    ~~

    Quantitative analysis of the plasma compositions was performed by
mass  spectroscopy.  In this method,  the ratio of CHgBr response (peak)
heights were compared before and during the plasma reactions.  Conven-
tional  analytical methods were precluded because of the toxicity of the
methyl bromide gas.  Figure A-7 illustrates the  method.   Decomposition
was calculated as greater than 99 percent, which was  the limit of sensiti-
vity for the mass spectrometer unit.
                                   49

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 M/E'
                                              OXYGEN PLASMA BACKGROUND
                                              CO,
                                           i I i i i i
                                                 I ,   , I
                                                          i I
                                                                I i i i I I  i i  . I
            10    15
                      20
                           25    30    35    40    45    50    55
                                                                60    65
                                                                          70
M/E'
                                               IN-LINE ANALYSIS MALATHION
                                              CO-
                                                   SOT
                                                                   SO,
                                  i i I I
                                                   i i i I i i i i I i i i i I i i i i  I .
10    15    20   25    30    35    40    45   50    55    60    65
                                                                           I I I i i I i i I
                                                                          70   75
 •RATIO OF MASS TO CHARGE; VALUES APPLY TO IONS FORMED FROM NEUTRAL GAS MOLECULES PASSING THROUGH
  MASS SPECTROMETER.



   Figure A-4.  Mass  spectra  of gaseous effluent from reaction of

                    Malathion in oxygen plasma (Run 31-16)
                                         50

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                                             OXYGEN PLASMA BACKGROUND
                                             CO!
                                             I I i i I I I i
                                                                    I i i I i I i
   >-».5     10
                15
                     20
                          25
                               30
                                    35
                                         40
                                              45
                                                   50
                                                         55
                                                                        70
                                                                             75
                              COT
                                        IN-LINE ANALYSIS AROCLOR NO. 1242
M/E*-*-5     10"    15    20    25    30    35    40    45    50    55   60    65    70    75
  •RATIO OF MASS TO CHARGE; VALUES APPLY TO IONS FORMED FROM NEUTRAL GAS MOLECULES PASSING THROUGH
  MASS SPECTROMETER.
Figure A-5.   Mass spectra of gaseous effluent from reaction of
                 Aroclor No.  1242  PCB in oxygen plasma (Run  31-10)
                                       51

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                         CO,
                                          OXYGEN PLASMA BACKGROUND
 M/E-*- 5
                    20
                         25
                              30
                                  35
                                                 50
                                                     55
                                                          60
                                                               65
      I
           I
               _L
                             CO
                     I
                         I
                                           IN-LINE ANALYSIS AROCLOR NO. 1254
                                          COl
                                                 Jj
                                                     _h
 M/E' »• 5    10   15    20    25    30   35    40    45    50    55   60
                                                               65
                                                                    70   75
     •RATIO OF MASS TO CHARGE; VALUES APPLY TO IONS FORMED FROM NEUTRAL GAS MOLECULES PASSING THROUGH
      MASS SPECTROMETER.



Figure A-6.   Mass spectra of gaseous effluent from reaction of

                 Aroclor No.  1254 PCB in  oxygen plasma (Run  31-62)
                                      52

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          100


           90


           80


           70
        1/1
           50
        -J  40
        <
        Z
        o
        «/»  30
           20
           10
            0
METHYL BROMIDE PEAK
          -CURVE 1,
          PLASMA OFF
                                 -CURVE 2,
                                  PLASMA ON
               80   85   90   95  100  105
              CH Br MASS SPECTROMETER IONS
                 o

       Fraction of CI-LBr remaining when plasma on:

            Peak height plasma; On   _ <0.5 <
            Peak height plasma: Off  "   92   "
       Therefore/ CH«Br decomposed >99% in plasma reaction
Figure A-7.  Mass spectroscopic analysis of methyl bromide
             oxygen plasma reaction (Run 28-94)
                            53

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A. 2. 5  Troysan PMA-30, Phenylmercuric Acetate  —  Oxygen Plasma
       (Figure A^

    In-line analysis indicated that almost all the oxygen carrier gas
(M/E = 32) had reacted.  The main gaseous products were carbon dioxide
(M/E = 44, 28, 22,  16,  14,  12), carbon monoxide  (M/E = 28,  16, 14, 12),
and water (M/E = 18, 17, 16) with minor amounts  of low-molecular weight
hydrocarbons.  Most of the ions observed in the background plasma were
those which are formed from residual background  gases,  such as argon
(M/E = 40, 20), which are always  present in the mass spectrometer.

A. 2. 6  Troysan PMA-30 -  Steam Plasma (Figure A-9)

    The main gases observed were carbon dioxide (M/E  = 44,  28, 22, 16,
14, 12), carbon monoxide (M/E = 28, 16,  14,  12),  water (M/E -  18,  17, 16),
and a small amount of benzene  (M/E =  78, 77,  50,  51, 52).  There was  no
sign of the methyl alcohol solvent,  which has a unique ion at M/E = 31.   No
sign of the possible product, dimethylmercury, was observed in which the
high-mass range  (not shown) was searched at high sensitivity.  Most of the
ions observed in the plasma background were those formed from  residual,
background gases in the mass  spectrometer,  such as  argon (M/E = 40,  20),
or small amounts of aromatic ions (M/E = 78,  77,  76, 50, 51, 52).

A. 2. 7  Kepone — Oxygen Plasma  (Figure A-10)

    The main gaseous products observed  were carbon dioxide (M/E  = 44,
28, 22,  16, 14, 12), carbon monoxide (M/E  = 28,  16,  14,  12), and water
(M/E = 18, 17, 16).  Further scanning in  the high-mass spectrometer range,
1 to 250,  using a high-sensitivity setting,  showed no sign  of phosgene or
chlorinated hydrocarbons.  Hydrogen chloride, extremely water-soluble,
was found as  an ice mass deposited in the liquid nitrogen trap.
                                  54

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                                                  OXYGEN PLASMA BACKGROUND
                                                       100 x GREATER SENSITIVITY

                                                        I I , I I I , I I  I I , I I I I ,
 M/E*-»5
           10
                15
                     20    25   30   35   40   45    50    55    60    65
                                                                      70    75
              OH -|
                                             IN-LINE ANALYSIS TROYSAN PMA-30
M/E*
           10
                15
                     20    25   30   35
                                        40   45
                                                  50    55    60    65    70    75
       •RATIO OF MASS TO CHARGE; VALUES APPLY TO IONS FORMED FROM NEUTRAL GAS MOLECULES PASSING THROUGH
       MASS SPECTROMETER.


    Figure A-8.   Mass spectra of gaseous effluent from reaction of

                     Troysan PMA-30 (phenylmercuric acetate methanol

                     solution) in oxygen plasma (Run 31-118)
                                      55

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                  OH

                                              OXYGEN PLASMA BACKGROUND
                                                   100 x GREATER SENSITIVITY
                                   O2 ISOTOPE
  *-^5    10    15    20    25    30    35   40    45    50    55    60    65    70    75
              OH
                          CO
     I i i
                                             IN-LINE ANALYSIS TROYSAN PMA-30 AND STEAM
                                                   100 x GREATER SENSITIVITY
                                                            I < ' ' » I < ' ' ' t ' ' ' ' I
M/E'*-5     10    15   20    25   30   35    40   45    50    55    60    65    70    75
     •RATIO OF MASS TO CHARGE; VALUES APPLY TO IONS FORMED FROM NEUTRAL GAS MOLECULES PASSING THROUGH
      MASS SPECTROMETER.



 Figure A-9.  Mass spectra of gaseous  effluent  from reaction of

                 Troysan PMA-30  (phenylmercurie acetate methanol

                 solution)  in  steam plasma (Run 31-190)
                                     56

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           OXYGEN PLASMA BACKGROUND
                                                                                   Ar
                                                                                  A
                                                                CO,
                                                           L LJ_J  I  I  I  I  I  I  I  I I
01
-o
         M/E*—»• 5        10        15        20


            IN-LINE ANALYSIS KEPONE SOLUTION
                            25
                             30
                             35
           H,
          H
          i  I  I  I  .  I I  I  I  •  i  i  i  I
                                         I  I  I  I  I I  i  I  I
        M/E*
10
15
20
25
30
35
40
45
50
        •RATIO OF MASS DIVIDED BY CHARGE VALUES APPLY TO IONS FORMED FROM NEUTRAL GAS MOLECULES PASSING
         THROUGH THE MASS SPECTROMETER.

                Figure A-10.   Mass spectra of gaseous effluent from reaction of Kepone-methanol/
                                acetone in oxygen plasma

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                               Appendix B

        PROPERTIES OF PESTICIDES AND HAZARDOUS WASTES

     Chemical and physical properties and specifications of the materials
 studied in the program are listed in this section.
B. 1 MALATHION

    American Cyanamid "Cythion" ULV (ultra low volume) grade was ob-
tained from the manufacturer in commercial form, for which specifications
are given as follows:
Chemical name:


Structural formula:
Purity:

Odor:

Vapor  pressure:

Boiling point:

Melting point:

Solubility:




Flash point, Tag Open Cup:

Viscosity:
Toxicity,
              , acute,  oral:
O, O- dimethyl phosphorodithioate of diethyl
mercaptosuccinate

      S    CH2C02C2H5

CH3O-P-S-CHCO2C2H5
      OCH3

95%,  minimum

Slight, characteristic

4 x 10"5 torr at 30°C

156-57°C, 0. 7 torr,  slight decomposition

2. 9°C

140 ppm in H2O,  25°C. Soluble in most
alcohols, esters,  aromatic solvents, and
ketones.  Poor solubility in aliphatic
hydrocarbons

Greater than 163°C (325°F)

40°C, 17 centipoises
25°C, 37 centipoises

1, 375 mg/kg male albino  rats, anticholin-
esterase behavior
                                  58

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B. 2  POLYCHLORINATED BIPHENYLS
    Two different grades were evaluated.  These were Aroclor Nos.  1242
and 1254,  obtained from Monsanto, St.  Louis,  Mo.  Specifications and
properties are listed below:
                                   Aroclor
                                  No.  1242
Average molecular com-
position:
Chlorine (%)

Appearance:


Distillation range (°C):

Flash point (°C),
Cleveland Open Cup:

Fire point (°C),
Cleveland Open Cup:

Evaporation loss (%)
163°C (325°F), 5 hr:

B. 3  METHYL BROMIDE GAS
C12H7C13
(98% between
C12H8C12 and
C12H5C15)
42
                            Aroclor
                           No.  1254

                      CioHsClc
                      (98% between
                      Cl2H6Cl4 and
                      C12H3C17)

                      54
                      Light-yellow viscous
                      liquid

                      365-90
Clear,  mobile oil


325-366


176-180               None to boiling point


None to boiling point   None to boiling point
3.0-3. 6
                      1.1-1.3
    Methyl bromide was obtained as a liquefied gas from Matheson Gas
Products Company.  Its specifications are as follows:
Chemical name:

Formula:

Purity:


Appearance:

Odor:
Methyl bromide, or bromomethane

CH3Br

99. 5% CH3Br (min. )
0.015% H2O (max.)

Colorless

None, except at high concentrations where
it has a chloroform-like odor
Vapor pressure,  21°C&0°C):   13 psig (0. 9 kg/cm2 gage)
Boiling point, 1 atm:
3. 5°C (38. 2°F)
                                  59

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Freezing point,  1 atm:         -93. 7°C (-136. 7°F)

Flammability:                 Limited to narrow range of 13. 5-14. 5% in air

Autoignition temperature:      538°C(998°F)

Toxicity:                      Highly toxic; 20-ppm skin exposure, averaged,
                              8-hr day OS HA limits


B.4  PHENYLMERCURIC ACETATE,  PMA

    Commercial quantities of PMA solutions were obtained from Troy
Chemical Company,  and PMA 100 percent solids from Aldrich Chemical
Company and American Drug and Chemical Company.  Troysan PMA-30
was the principal material used for the detoxification studies.  Specifica-
tions  and properties are listed as follows:

Chemical name:               Phenylmercurie acetate
Structural formula:
 Melting point:                 149°C

 PMA solids content in
 Troysan PMA-30:             30%, min.

 Metal content in PMA-30:      18%Hg

 Other components in PMA-30:  Principally methyl alcohol, ammonium acetate

 Dilution in water PMA-30:     Complete

 Toxicity,  LD5Q, acute, oral:   22 mg mercury/kg,  rat test animals


 B. 5  KEPONE

    Allied Chemical 80 percent Kepone concentrate,  Code 9406, was used
 as the starting material.  Approximately 0. 5 Ib was available for the tests.
 Properties are as follows:

 Chemical name:               Decachloro-octahydro-1, 3, 4-metheno-2H-
                              cyclobuta (c, d) pentalene-2-one, or chlor-
                              decone.  (Ref. 12)
                                   60

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Structural formula:
                                                  Cl
 Contents:

 Melting point:



 Solubility
 Toxicity,
             80% Kepone, 20% inert clay-type support

             Technical product, more than 90% pure;
             sublimes at near 350°C, with some decom-
             position

             Soluble in acetone, methanol (small amount
             exclusive of clay-support not soluble in
             CE^OH). Isolatable  as mono- or tri-hydrate;
             forms solvates with acids, alcohols, amines,
             and thiols,  and soluble in strongly alkaline
             solutions.  Recrystallizable from 90% aque-
             ous ethanol

acute, oral:   114 to 140 mg/kg,  rat test animals
                                    61

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                               Appendix C

      CHEMICAL REACTIONS IN ARGON AND HYDROGEN PLASMAS

     This section includes the results of those plasma reactions which oc-
 curred in argon and hydrogen environments.  The tests were continued
 during the program until it became apparent that these or related carrier
 gases would not be suitable for detoxification in a microwave plasma pro-
 cess.


 C. 1  MALATHION-ARGON AND MALATHION ARGON-OXYGEN PLASMAS

     Decomposition reactions of Malathion in 200-250 W, 100 torr pressure,
 pure argon, and mixed argon-oxygen plasmas were investigated in the lab-
 oratory-scale plasma system.  In pure argon, the yellow-brown products
 were offensive and malodorous, similar to mercaptan and disulfide com-
 pounds.  In mixed 50/50 vol.% argon-oxygen, the products were essentially
 identical to that of the 100% oxygen plasma reactions, whereas in 80/20
 argon-oxygen plasmas,  mercaptan (skunk-like) but not sulfide, odors were
 again evident.  Although analyses of these materials were not pursued ac-
 tively, it was possible,  nevertheless,  to postulate the products of decom-
 position.  This was based on  the mass fragment formations which result
 from the ionization processes that occur during mass spectrescopic analy-
 sis of Malathion and related materials (13).

     They are presented as follows:

      S      H      I Ar plasma ]           S                S    S
CH.O-P -4-Sf C-CO9C,H,.	  1)  CH.O-P-SH   2)  CH,O-P-S-S-P-OCH,
   O   | '     I    ^ ^ 3               O  i              «3   i      i     O
      OCH,  C-CO.C-hL                  OCH_            OCH. OCH,
          O  A    ^ / 0                      J                O    o
            H2



                                        H     H

                               3)  HO-C-C-S-S-C-CO,H    4)   CH-CO,C,H_
                                     &  |      |     i           ||     * «m O
                                  H02C-CH2  I-
                              5)   H-S and lower hydrocarbon sulfides, mercaptans
                                  62

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C. 2  PCS -  ARGON PLASMA REACTIONS

    Aroclor No. 1242 liquid was passed through a 250 W argon plasma at
100 torr.  In  contrast to oxygen plasma results, a sol vent-soluble, black
tar-like oil formed in the reactor tube and dripped slowly down the sides
during the reaction.  The gases evolved were determined by mass spectres-
copy to be the following:

    (1) Hydrogen chloride     HC1

    (2) Ethylene              CH2 - CH2

    (3) Acetylene            HC^CH

    (4) Methyl chloride       CH3C1

    Although the tars were not analyzed extensively,  later infrared deter-
mination of similar processes in hydrogen indicated that the black materials
contained substantial quantities of unreacted PCB's.

C. 3 PCB -  ARGON-OXYGEN PLASMA REACTIONS

    In a 50-50 volume percent oxygen/argon plasma,  however, under lab-
oratory-scale conditions similar to those  described in subsection C. 2, tar-
like liquids,  were not formed in the reactor.  There were not more than
traces, if any, of  unsaturated hydrocarbons, chlorine oxide, carbonyl
chloride,  or  methyl  chloride in the gas effluent.  The products were as
follows:

     (1)  Hydrogen chloride     HC1

     (2)  Carbon dioxide        CO2

     (3)  Carbon monoxide      CO

     (4)  Water               H2O


C.4 PCB  -  HYDROGEN PLASMA REACTIONS

     PCB's 1242 and 1254 were passed through the  expanded-scale system
in which a hydrogen plasma at 50  torr had been activated. Powers ranged
from 4. 0 to 4. 6 kW.  The principal gaseous reaction products, as deter-
mined by the mass spectrometer, were as follows:

     (1)  Hydrogen chloride    HC1

     (2)  Acetylene            HC s CH


     (3)  Methane              CH4
                                   63

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    A black, oily liquid with an aromatic naphthalenic odor dripped into the
receiving tube after several minutes of reaction time.  Analysis for chlorine
content and infrared spectroscopy indicated that the liquid was principally a
form  of the original starting material.

C. 5 METHYL  BROMIDE -  ARGON PLASMA REACTIONS

    Gaseous methyl bromide (2 to 3 g/hr) was passed through 300 to 400 W
argon plasmas  at 50 torr in the laboratory- scale system.  The products of
reaction detected by the mass spectrometer were as follows:

    (1)  Bromine             Br2

    (2)  Hydrogen bromide     HBr

    (3)  Ethylene             CH2=CH2

    (4)  Acetylene             CH s CH


    (5)  Methane              CH4

    Carbonaceous flake deposits were formed in the reactor tube.  Quanti-
tative analysis  by the mass spectrometer showed that not less than 99 per-
cent conversion had occurred.

C. 6 METHYL  BROMIDE -  ARGON- OXYGEN PLASMA REACTIONS

    Reactions of methyl bromide in  50-50 vol. % argon- oxygen plasmas
yielded the following products as estimated by the mass spectrometer:
     (1)  Bromine

     (2)  Hydrogen bromide    HBr

     (3)  Ethane               C0HC
                               Z D

     (4)  Carbon dioxide        COg

     (5)  Carbon monoxide      CO

     (6)  Water                HgO

     The unequivocal identification of several of these materials was diffi-
cult  because of similarity in their masses, e. g. , HBr+, M/E = 80,  82,
which registers adjacent to Br+,  M/E = 79, 81 on the spectrometer re-
corder charts.   There was also no indication of the carbonaceous  deposits,
i. e. , flakes,  which were formed  in the 100 percent argon plasmas.  This
is identical to the absence of carbon deposits reported above for 50-50
argon/ oxygen PCB plasmas.
                                   64

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                                   TECHNICAL REPORT DATA
                           (Please read Instructions on the reverse before completing)
  REPORT NO.
  EPA-600/2-77-030
            3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
                                                           5. REPORT DATE
  DEVELOPMENT  OF  MICROWAVE PLASMA DETOXIFICATION
  PROCESS FOR  HAZARDOUS WASTES - PHASE  I
              April  1977 (Issuing Date)
            6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
  Lionel J.  Bailin
  Barry  L.  Hertzler
            8. PERFORMING ORGANIZATION REPORT NO.
  PERFORMING ORGANIZATION NAME AND ADDRESS
  Lockheed Palo Alto Research Laboratory
  Lockheed Missiles and Space Company,  Inc.
  Palo Alto,  California  94304
                                                           10. PROGRAM ELEMENT NO.
              IDC 618
             11. CONTRACT/GRANT NO.

               Contract 68-03-2190
12. SPONSORING AGENCY NAME AND ADDRESS
  Municipal  Environmental Research  Laboratory—Cin.,OH.
  Office  of  Research and Development
  U.S.  Environmental Protection Agency
  Cincinnati,  Ohio  45268
             13. TYPE OF REPORT AND PERIOD COVERED
              Final for Phase  I,  1976
             14. SPONSORING AGENCY CODE

              EPA/600/14
15. SUPPLEMENTARY NOTES

   This  contract effort is continuing,  and currently Phase  II  is  underway.
16. ABSTRACT
  The  microwave process described  in this report is a relatively new application
  of what has been termed the  "fourth state of matter",  or  the "plasma state".  It
  is the first practical application of a microwave discharge to the decomposition
  of chemical compounds in significant quantities.  This report describes a recent,
  successful, R&D effort in which  a  former "grams-per-hour" system was scaled up  to
  a 5  to 7 pounds-per-hour system, and then its performance was verified with several
  typical hazardous materials.   The  materials tested and detoxified were Malathion,
  methyl-bromide, polychlorinated  biphenyls, phenylmercuric acetate, and Kepone.
  Complete detoxification resulted.

  Further benefits of the process  are the competitive,  reasonable costs of about  $0.20
  per  pound of material processed, including all costs.

  The  process warrants  further development, namely additional scale-up to pilot and
  field units.  Presently, units up  to 100 pounds per hour  or so appear feasible  to
  construct and be operable within two or three years.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTlFIERS/OPEN ENDED TERMS
                             COSATI Field/Group
  detoxification,  degradation,
  hazardous  materials, waste disposal,
  microwave  equipment, pyrolysis,
  industrial  waste treatment,
  waste treatment,
  organic wastes,
  electromagnetic  radiation
  new microwave tech-
  nique,  microwave-
  disposal  process
   13B
 18. DISTRIBUTION STATEMENT

   Release to  Public
19. SECURITY CLASS (ThisReport)
  unclassified
21. NO. OF PAGES

    79
                                              20. SECURITY CLASS (This page)

                                                unclassified
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EPA Form 2220-1 (9-73)
                                             65
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