EPA/600/2-86/006
                                           January 1986
          PIC FORMATION UNDER PYROLYTIC
          AND STARVED AIR CONDITIONS
                Barry Dellinger
                Douglas L. Hall
                 John L. Graham
                Sueann L. Mazer
                 Wayne A. Rubey
    University of Dayton Research Institute
              Dayton, Ohio  45469

                      and

                  M. Malanchuk
      U.S. Environmental Protection Agency
            Cincinnati, Ohio  45268
            Grant No. CR 81-0783-01

              EPA Workplan #01249
                 Item #4098[A]
                Project Officer
              Robert E. Mournighan
            Thermal Technology Staff
           Thermal Destruction Branch
       Alternative Technologies Division
Hazardous Waste Engineering Research Laboratory
     U.S. Environmental Research Laboratory
             Cincinnati, Ohio 45268
HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY
       OFFICE OF RESEARCH AND DEVELOPMENT
      U.S. ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI, OHIO  45268

-------
                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO
   EPA/600/2-86/006
                                 l.
3. RECIPIENT'S ACCESSION NO.
     b  U54227AS
TITLE AND SUBTITLE
             PIC Formation  Under Pyrolytic and
   Starved Air Conditions
                                                           5. REPORT DATE
                                                             January 1986
                                                          6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)               ~~
  Barry Dellinger,  Douglas L. Hall, John L.
  Graham, Sueann  L.  Mazer, Wayne A. Rubey
                                                         8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
  University of Dayton Research Institute
  300 College Park
  Dayton, OH  45469
                                                         10. PROGRAM ELEMENT NO.
                                                           D109
                                                         11. CONTRACT/GRANT NO.
                                                             CR-810783-01-0
12. SPONSORING AGENCY NAME AND ADDRESS
  U.S. Environmental  Protection Agency
  Hazardous Waste Engineering Research Laboratory
  26 W. St. Clair St.
  Cincinnati, OH 45268
                                                         13. TYPE OF REPORT AND PERIOD COVERED
                                                           Progress Oct.  84  - Oct. 85
                                                         14. SPONSORING AGENCY CODE
                                                           EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
       A comprehensive  program of laboratory studies based  on the non-flame mode of
  thermal decomposition produced much data on PIC  (Products of Incomplete Combustion)
  formation, primarily  under pyrolytic and starved air  conditions.

       Most significantly,  laboratory results from non-flame studies were compared to
  those from various field'tests to evaluate incinerability relationships.  Measurement
  of  gas-phase thermal  stability in an atmosphere of low oxygen concentration yielded
  results of incinerability  ranking that were far more  consistent with the findings
  from field tests than any  one  of  several common methods applied in the past such as
  those that employed heat of  combustion, autoignition  temperature,  etc.

       The results of four experimental studies were presented as significant
  contributions to developing/expanding the data base on POHC  (Principal Organic
  Hazardous Constituent) stability  and PIC formation for pure  compounds and mixtures.
17.
                               KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                             b.IDENTIFIERS/OPEN ENDED TERMS
                                                                      c.  COS AT I Field/Group
18. DISTRIBUTION STATEMENT

       RELEASE  UNLIMITED
                                            19. SECURITY CLASS (This Report)
                                              Unclassified
              21. NO. OF PAGES
                      57
                                             20. SECURITY CLASS (This page)
                                                Unclassified
                                                                        22. PRICE
EPA Form 2220-1 (R«v. 4-77)   PREVIOUS EDITION is OBSOLETE

-------
                      NOTICE

This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication.  Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
                       11

-------
                                  FOREWORD
     Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased generation
of solid and hazardous wastes.  These materials, if improperly dealt with,
can threaten both public health and the environment.  Abandoned waste sites
and accidental releases of toxic and hazardous substances to the environ-
ment also have important environmental and public health implications.  The
Hazardous Waste Engineering Research Laboratory assists in providing an
authoritative and defensible engineering basis for assessing and solving
these problems.  Its products support the policies, programs and regula-
tions of the Environmental Protection Agency, the permitting and other
responsibilities of State and local governments and the needs of both large
and small businesses in handling their wastes responsibly and economically.

     This report describes the results of various laboratory studies
designed to correlate predictions based on laboratory findings to field
results, with emphasis on Products of Incomplete Combustion (PIC) formation
under pyrolytic and starved air conditions in the laboratory tests.

     For further information, please contact the Alternative Technologies
Division/Thermal Destruction Branch of the Hazardous Waste Engineering
Research Laboratory-
                                     David G. Stephan, Director
                           Hazardous Waste Engineering Research Laboratory
                                     iii

-------
                         PIC FORMATION UNDER PYROLYTIC
                          AND STARVED  AIR  CONDITIONS

                                      by

                      Barry  Dellinger,  Douglas L.  Hall,
                       John  L.  Graham,  Sueann L. Mazer
                              and Wayne A. Rubey
                   University of Dayton Research Institute
                             Dayton, Ohio  45469

                                    and

                               Myron Malanchuk
                     U.S.  Environmental Protection Agency
                          Cincinnati,  Ohio   45268
                                  ABSTRACT

      The University  of  Dayton Research  Institute carried out a comprehen-
 sive program of  laboratory  studies  based on  the non-flame mode of  hazardous
 waste thermal decomposition.  The results of those studies were compared
 to those of flame-mode  studies  and  of field  tests to evaluate the  incin-
 eration model proposed.   That model was developed upon the premise that
 incinerators do  not  operate continuously at  optimum conditions.  As a
 result, as much,  or  more, than  one  percent of the feed and its flame treat-
 ment products must undergo  further  decomposition in the post-flame region
 to meet the >99.99%  Destruction and Removal  Efficiency (DRE) criterion.

      Thermal decomposition  (non-flame)  results were compared to those  from
 a flame-mode study.  That comparison supported a common order of stability
 ranking of individual compounds set forth by the findings from both series.

      Laboratory results from  non-flame  studies were compared to those  from
 various field tests  to evaluate incinerability relationships.  It  was
 strongly evident  that the results of the laboratory tests where low oxygen
 conditions (gas-phase thermal stability at low oxygen concentrations)  pre-
 vailed,  presented a  significantly superior incinerability correlation  to
 field tests  than  any of the other proposed methods of ranking.  Those
 methods  included  heat of combustion, auto-ignition temperature, theoretical
 flame-mode kinetics,  experimental flame failure modes, ignition delay  time,
 as well  as gas-phase thermal stability at high oxygen concentration.

      The  results  of four experimental studies were presented as support to
 developing/expanding the data base  on Principal Organic Hazardous  Con-
 stituent  (POHC) stability and Products of Incomplete Combustion (PIC)
 formation for pure compounds and mixtures.

     Several studies  were proposed for further laboratory investigation
of the thermal treatment process.


                                     iv

-------
                                   CONTENTS
Notice	,„	   ii
Foreword	  iii
Abstract „	. ^ .	   iv
Tables	   vi
Figures	  vii

     Introduction	    1
     Development of an Incineration Model	.„	    2
     Comparison of Flame and Thermal Decomposition Results 	-    6
     Correlation of Laboratory Predictions and Field Results  	   13
       Discussion	   19
       Summary and Conclusions......	   20
     Expansion of Data Base on POHC Stability and  PIC For-
       mation for Pure Compounds and Mixtures 	   21
       Thermal Decomposition of CRF Soup-1 	   21
       Formation of PCDFs and Other PICs from PCBs 	   23
       Formation of PICs from Chloroform	   33
       Formation of PICs from Polychlorinated Phenols  	   36
       Expansion of Pure Compound Kinetic and Thermal
         Stability Data Base.....	   36

References	   46

-------
                                 TABLES

Number                 ,                                               Page

 1  Calculated Destruction Efficiency for Representative Hazar-
      dous Organics 	   4
 2  Comparison of Flame and Non-Flame (Thermal) Stability
      Ranking of Various Test Compounds 	   8
 3  PICs Found in Diffusion Flame Combustion of Chlorobenzene,
      Benzene and HC1 Mixture and Thermal Decomposition of a
      Mixture of Carbon Tetrachloride,  Toluene, Chlorobenzene,
      Trichloroethylene and Freon 113 	  10
 4  Results of Statistical Analyses of  Observed vs.  Predicted
      Thermal Stability Rankings 	  15
 5  Summary of Thermal Decomposition Testing for Components of
      Hazardous Waste Mixture #1 	  22
 6  Thermal Reaction Products Observed  from the Thermal Decompo-
      sition of CRF Soup-1	  24
 7  Major Thermal Reaction Products Tentatively Identified from
      the Thermal Degradation of 2,3',4,4',5-Pentachlorobiphenyl ....  28
 8  Maximum Weight Percent Yield of PCDFs as a Function of
      Reaction Atmosphere 	  30
 9  Thermal Decomposition Products Observed from Chloroform and
      Pentachloroethane 	  37
10  Thermal Degradation Products from Pentachlorophenol 	  40
11  Summary of Thermal Decomposition Data	  42
12  Summary of First Order Kinetic Results	  43
13  Summary of Fractional Reaction Order  Calculations	  44
                                     vi

-------
                                  FIGURES

Number                                                                Page

 1  Comparison of EERC Model Prediction with Predictions of
       UDRI Two-Zone Incineration Model for the Acurex Subscale
       Boiler	    7
  2  Concentration vs. Temperature for Propane Oxidation in Air
       at a Gas-Phase Residence Time of 2.OS	   11
  3  Comparison of Flow Reactor Generated Thermal Decomposition
       Profile vs. Predicted Results from Computer Modeled Gas-
       Phase Free Radical Mechanism for Propane Oxidation 	   12
  4  Thermal Decomposition Behavior of Toluene and Freon 113	   27
  5  PCDF Formation/Destruction Profiles for  = 1.0 and a Gas
       Phase Residence Time of 2.OS 	   31
  6  Weight Percent (Normalized to Non-Decomposed Parent Peak) vs.
       Temperature for Chloroform and Selected Decomposition
       Products (cj> = 0.76, 2.OS Residence Time) 	   34
  7  Weight Percent (Normalized to Non-Decomposed Parent Peak)
       vs. Temperature for Pentachloroethane and Its Major
       Decomposition Product Tetrachloroethylene (4 = 0.76,
       2.OS Residence Time) 	   35
  8  Possible Pathways for the Thermal Decomposition of Chloro-
       form	   38
  9  Thermal Decomposition Profiles for PCP and TCP	   39
                                    VII

-------
                       PIC FORMATION UNDER PYROLYTIC
                        AND STARVED AIR CONDITIONS
INTRODUCTION

     The University of Dayton Research Institute (UDRI) has addressed
various incineration issues in the first 18 months of the Cooperative
Agreement CR-810783-01-0 and has produced upwards of 15 publications/
presentations based on the several projects during that period.  However,
the projects encompassing "PIC Formation Under Pyrolytic and Starved Air
Conditions" is emphasized in the following report.

     The ultimate goal of incineration research is to understand the
process of incineration  to the extent that one can accurately predict
incinerator emissions and how changing design and operational parameters
affect pollutant emission rates.

     Emissions of hazardous organic compounds fall into two general cate-
gories, those compounds in the waste feed which are not totally destroyed
and those compounds formed from the partial degradation of the waste.
Designations for these classes have been borrowed from the regulatory
designations of Principal Organic Hazardous Constituents (POHCs) and Pro-
ducts of Incomplete Combustion (PICs).  Since regulation of incineration
will always require some type of testing or monitoring of the actual in-
cinerator, a desirable product of research would be information that can be
used to reduce the testing burden and ensure that the proper emissions and
operating parameters are being monitored that will ensure environmentally
safe waste disposal.  This has been the goal of the research program con-
ducted by UDRI.

     The complexity of the incineration process, the differences in inciner-
ator designs, and the difficulties in monitoring changing operating con-
ditions makes the accurate prediction of absolute incineration performance
an essentially impossible task.  A more reasonable goal is to be able to
predict the relative destruction efficiency of POHCs and the relative
emission rate of PICs for a given incinerator.  This is a goal which is
consistent with the goal of reducing the need for incinerator testing,
since one could then simply conduct tests focusing on the least "inciner-
able" POHCs and the PICs of greatest yield as predicted by laboratory
testing and research.   If these compounds are found to meet regulatory
requirements then presumably so would the other POHCs and PICs.  Of course,
one 'must have sufficient knowledge of the effect of incineration parameters
on POHC and PIC emissions to correctly define the conditions for the labora-

                                     1.

-------
  tory and field studies and allow for subsequent changes in these conditions
  on the incinerator.   Laboratory and field testing under "worst"  case  con-
  ditions would appear to be the best means of assuring continuing incinera-
  tor compliance.   Once initial  compliance  has been established, a method  of
  monitoring for continuing compliance is also necessary.  This  defines a.
  second goal of our  research program which is to identify appropriate  species
  or operating parameters for continuous  compliance monitoring.

  DEVELOPMENT OF AN INCINERATION MODEL

       The first step in determining which incinerator  parameters  signifi-
  cantly affect POHC  and PIC emission is  to develop a simple,  qualitative
  incineration model  that can be used to  determine major effects.

       In determining the destruction efficiency  of hazardous  organic
  materials by incineration, chemical reactions occuring in condensed
  phases may effectively be neglected. This is true due to mass and heat
  transfer considerations.  Thus, we may  primarily concern ourselves with
  gas-phase chemistry although the nature of the  passage of material from
  condensed phase into the gas-phase by physical  processes may be  impor-
  tant.

       Once in the gas phase, there exists  more than one mode  of destruction
  of the material and it is necessary to  address  the factors affecting  these
  destruction modes.   Two modes  are clearly evident and they may be designated
  as direct flame and thermal (non-flame) decomposition.

       Both flame mode and thermal decomposition  studies indicate  that  any
  known organic waste can be destroyed in an incinerator to greater than
  99.99% destruction  efficiency  (DE) if it  is operating under  theoretically
  optimum (Conditions  (1-3).  Thermal decomposition can  be expected at less
  than 1000C in flowing air at a mean residence time of 2.0 seconds. Flame
^destruction of waste droplets  may occur in flames operating  in excess of
  850C.

       Excursions, or fault modes, are probably the controlling phenomena
  for incineration efficiency.   Four parameters (atomization inefficiency,
  mixing inefficiency, thermal failure, and quenching)  have been identified
  as failure modes in flames (2).  Laboratory studies have shown that rela-
  tively small excursions from ideality for these parameters can easily drop
  measured flame destruction efficiencies from greater  than 99.99% to 99%  or
  even less than 90%  (three orders of magnitude).  Non-flame upset parameters
  can be conveniently  classified in terms of distributions of  oxygen, resi-
  dence time, and temperature (1-4).

       The key to understanding  the significance  of upset conditions is that
  only a very small fraction of  the total volume  of the waste  needs to  ex-
  perience these less  than optimum conditions to  result in significant  devi-
  ations from the  targeted destruction efficiencies.  To illustrate how
                                       2.

-------
 laboratory  thermal  decomposition testing  relates  to upset modes  and  can
 potentially be used to  predict  observed emissions  from full  scale  facili-
 ties,  let us  examine a  specific example.

     Previous research  has  shown that  the destruction kinetics of  typical
 hazardous organic compounds  can be  described  satisfactorily  using  simple
 pseudo-first  order  kinetics  (1).  Although different or more complex models
 may be used,  the actual model used  is  not important for the  scope  of this
 discussion.

     We will  first  examine  the  case of a  simple one-stage combustor where a
 waste  feed  mixture  is fed directly  into a turbulent flame and the  hot gases
 evolving from the flame pass on through a relatively long, high  temperature
 hold-up zone  prior  to exiting from  the system.  Representative reaction
 conditions  for the  flame can be chosen as an  average residence time of 0.1
 second and  a  bulk flame temperature of 1700K.  For the post-flame  zone, we
 may choose  a  mean residence  time of 2.0s  and  a bulk gas-phase temperature
 of HOOK.   Although a range  of  residence  times and temperatures  are actual-
 ly experienced by the individual molecules, the values chosen are  typical
 effective residence times and temperatures.

     As mentioned in the previous paragraphs, several destruction  failure
 modes  have  been identified  for  the  flame.   In this model, we will  assume
 that only 1%  of the waste feed  avoids experiencing the bulk  reaction con-
 ditions in  the flame.   This  might be caused by a reduced gas-phase resi-
 dence  time  from an  improperly operating nozzle or from experiencing a
 reduced temperature as  a result of  being  sealed in particulate matter.  A
 third  cause might be reduced time at temperature from quenching  by cold
 gases  or poor mixing with oxygen.

     This one percent of the waste  feed enters the post-flame zone.  The
 overall measured destruction efficiency at  the stack is the weighted aver-
 age of the  destruction  efficiencies of the  flame and post-flame  zones.  The
 results of  these calculations for hazardous waste of a range of  thermal
 stabilities are shown in Table  1.   From examination of the table, it is
 apparent that each  of the compounds is destroyed to essentially  the same
 efficiency  in the flame, i.e.,  greater than 99.99%.  In the  post-flame
 region, significant differences in  thermal  stability are observed.

     From examination of the last column  of the table, it is apparent that
 the overall destruction efficiency  parallels  the destruction efficiency in
 the post-flame region.  The  principal value of the overall DE is 99% in all
 cases, with the variations in DE  occurring  to the right of the decimal.
 The destruction achieved in  the flame determines the principal value, while
 the non-flame destruction efficiency determines the approach to  four nines.

     The overall destruction efficiencies  quoted in the table are  typical
 of preliminary results  reported for studies on full-scale incinerators.
The measured destruction efficiencies for essentially all full-scale sys-
 tems have exceeded  or approached  99.99% for most compounds.  Variations
have been in the third, second,  or  in some  cases, the first  decimal place.
                                      3.

-------
   TABLE 1.  CALCULATED  DESTRUCTION EFFICIENCY FOR REPRESENTATIVE
                          HAZARDOUS ORGANICS
                          Calculated  Destruction Efficiencies
                                     DE
                               DE
DE
Compound
(s"1)  (kcal/mole)   (Flame)  (Post-Flame)    (Overall)
Acetonitrile
Benzene
Chloroform
Tetrachlorobenzene
Tetrachloroethylene
Trichlorobenzene
4
2
2
1
2
2
.7xl07
.8xl08
.9xl012
.9xl06
.6xl06
.2xl08
40
38
49
30
33
38
99
99
99
99
99
99
.999+
.999+
.999+
.999+
.999+
.999+
66.357
99
99
98
77
99
.999+
.999+
.556
.127
.968
99.
99.
99.
99.
99.
99.
664
999+
999+
986
771
999+

-------
     A further  observation has been  that most  Incinerators can achieve  a
DE of 99.99%  for  essentially  all  waste  feeds when  operating  optimally.
However, optimum  operation cannot be attained  on a continuous basis.  If
an incinerator  could be sampled on a continuous basis, one would  probably
find that at  least 90% of the hazardous organic emissions occur in the
fraction of time  when the incinerator experiences  an upset.  Such upsets
could be loss of  flame, an overload  of  waste feed,  or a failure of a spray
nozzle.  It is  during these system upsets  that a large percentage of the
feed material can escape flame mode  destruction and the reaction  conditions
in the post-flame zones can be degraded from their steady-state operating
values.  Under  upset conditions,  the difference in waste incinerability may
be magnified, the non-flame zone  destruction comes  to even greater promi-
nence, and the  performance of the incinerator  fails to achieve four nines
for a greater number of components of the  waste feed.

     Poor mixing  of waste and oxygen in the afterburner gives rise to a
certain fraction  of the waste being  subjected only  to low oxygen condi-
tions.  Numerous  laboratory studies  have shown that destruction of the feed
material is much  slower under these  conditions and PIC formation is en-
hanced.  We again have the case where although most of the waste experi-
ences oxidizing conditions and is destroyed, the small fraction of the feed
experiencing  the  pyrolytic conditions may  be responsible for the emission.
The observation in field and  laboratory studies that most reaction products
are pyrolysis type products (e.g., benzene, toluene, naphthalene) tends to
confirm this  hypothesis.

     Although the conclusion  that a  subfraction of a fraction of the waste
feed is responsible for most hazardous  organic emissions may be surprising
at first, the same process is generally responsible for emission of most
air pollutants.   One is not really concerned with  the major chemistry, such
as in a power plant which forms carbon  dioxide and water;  but instead the
minor reaction  pathways which form sulfur  dioxide, sulfuric acid, and
nitrogen oxides.  These pathways  are responsible for less than 0.1 to 1% of
the stack emissions but are the reactions  of interest in pollutant forma-
tion.

     The applicability of this qualitative model has recently been con-
firmed by a more  complex model of  hazardous waste  incineration developed by
the Energy and  Environmental Research Corporation  (EERC) [5,6].  This model
includes considerations of furnace heat transfer,  flow, mixing, injection,
tracking, and kinetics.  UDRI pseudo-first order thermal decomposition
kinetics were used as inputs for  the model.  Thus  far, modeling results for
three pilot-scale hazardous waste  thermal  destruction systems have been
reported.  These  systems are the  Controlled Temperature Tower (CTT), the US
EPA's Combustion Research Facility's  (CRF) rotary kiln system, and the
Acurex subscale boiler.  The CTT  was  modeled under several modes of opera-
tion and failure modes including  standard, cooled, insulated, backheated,
fast quench,  and various droplet  vaporization points.  The CRF system was
modeled for varying loads, different  excess air levels, and kiln  or after-
burner flameout.  The Acurex subscale boiler was modeled for various fuel
heating values,  heat removal rates,  excess air rates, waterwall/nonwater-
wall modes,  various droplet vaporization points, and temperature  profiles.


                                      5.

-------
      In  each reported case the predicted relative destruction efficiencies
 correlated almost perfectly with the values for 199.99(1)  (temperature for
 99.99% destruction at 1.0 sec. residence time) of the test compounds.  For
 the  CTT,  the agreement was essentially perfect for every case.  For the  six
 test compounds modeled for the CRF, only methane exhibited a moderate
 deviation from the behavior predicted by purely pseudo-first order post-
 flame kinetics.  For the Acurex boiler, of the eight compounds modeled,
 only acetonitrile showed significant deviation (see Figure 1).

      The  excellent agreement between the ranking according to 199^99  (1)
 and  the EERC model are as predicted by our two-zone incineration model,
 illustrating the importance of post-flame reaction kinetics.  Although
 quantitative predictions are available from the EERC model, accurate pre-
 dictions  for complex incineration systems will require many years of model
 development and refinement.  However, the significance of post-flame
 chemistry in controlling relative POHC DEs has been clearly con-
 firmed.

      Thus, improvements of model accuracy can best be accomplished by more
 refined  post-flame kinetics.  Detailed flame kinetics are of less value
 since waste compounds subjected to the flame environment will essentially
 be totally destroyed.  Post-flame kinetics can be improved by addressing
 the  effect of varying oxygen levels and waste feed composition for mixtures.
 Most importantly, the development of data on formation of PICs is essen-
 tial.

      Comparison of UDRI generated laboratory flow reactor (non-flame) data
 with laboratory flame-mode data, illustrates the similarity in the reaction
 mechanisms for both zones, i.e., a free—radical degradation mechanism.
 These results suggest that many PICs can be formed from simple feed mix-
 tures and the POHC DEs and PIC yields may be very dependent upon the waste
 composition and oxygen level of the reaction atmosphere.  A detailed com-
 parison  of field and laboratory studies further indicates the importance of
 PIC  emissions in determining incinerator performance and how laboratory  data
 can  be used to predict PIC formation.

 COMPARISON OF FLAME AND THERMAL DECOMPOSITION RESULTS

      With our flow reactor systems at UDRI, we have generated thermal
 decomposition data on nearly 100 different hazardous organic compounds.
 The  experimental difficulties in generating similar flame data has resulted
 in a very limited data base for comparison.  However, a recently reported
 study has furnished some data for comparison (7).

      Thirteen compounds  of interest to hazardous waste incineration were com-
 busted in a laboratory diffusion flame.  The relative burning rates of these
 compounds were determined based on their flame front velocities.  A listing
 of these compounds and their rankings based on non-flame thermal degradation
 studies  is shown in Table 2.   For the six compounds for which thermal decom-
 position data is available,  the non-flame rankings are indicated.   Further-
more, the flame-mode rankings  for the remaining compounds are basically as
 one would predict for the thermal degradation of untested compounds.


                                      6.

-------
            r\J
            r\J
            o
            ro
            _c
            o
            (V)
            en
           -10
          CO
          LO
          CO
          CO
          en
          n
          o
            C.J
            o
            o
           UJ
           no
           O
                      i
                      CD
                           LOG  (FRflCTIQN UNREflClEO)
                                   1,2,3,4-tetrachlorobeniene
             ethane

carbon tetrachloride  O
                                 acetonitrile  O
             acrylonlt rile


        tetrachloroethylene
Figure 1.   Comparison of EERC model prediction with predictions of
            UDRI two-zone incineration model for the Acurex Subscale
            Boiler.  The results indicate  the control of overall
            relative destruction efficiencies of test compounds by
            post-flame chemical kinetics.
                                     7-

-------
      TABLE 2.  COMPARISON OF FLAME AND NON-FLAME  (THERMAL)  STABILITY
                       RANKING OF VARIOUS TEST  COMPOUNDS
     Compound
Relative Burning         UDRI Thermal
  jlate (Flame)[7] Stability  (Non-Flame)  Ranking
1,2, 4-Trichlorobenzene
m-Dichlorobenzene
o-Dichlorobenzene
1 , 6-Dichlor ohexane
Chlorobenzene
1-Chlor ohexane
Benzene
Dichloroisopropylether
1 , 2-Dichloropropane
n-Hexane
1,1, 1-Trichloroethane
Epichlorohydrin
1 , 2-Dichloroethane
10.9
13.5
12.6
25.6
28.4
34.7
60.0
87
219
736
844
1142
1500
ll
2
3

4

5



6


-"•Ranking of 1 is most stable
                                      8.

-------
     In a second flame experiment, various combinations of dichlorobenzene,
benzene, and hydrogen chloride (HC1) were combusted at 40% of stoichio-
metric air.  The identity and yield of these products were found to be
essentially invariant as long as the ratios of chlorine, hydrogen, carbon,
and oxygen were constant.  The observed PICs are listed in Table 3.

     Recently completed was a study of PIC formation from the thermal de-
composition of a mixture of carbon tetrachloride, toluene, chlorobenzene,
trichloroethylene, and Freon 113 (4).  Those PICs resulting from this
mixture that were also found in the flame combustion of chlorobenzene are
also noted in Table 3.

     The agreements between relative POHC stability and PIC production for
flame and non-flame studies is striking, particularly for PIC production.
Most of the differences in observed PICs are the lack of higher chlorinated
compounds from the thermal degradation studies.  This is probably due to the
fact that the chlorine content of the thermal degradation mixtures was only
6 mole percent while it was 50 mole percent for the flame study, the latter
favoring formation of higher chlorinated species.  The only other real
discrepancy was the lack of formation of biphenylene and chloroacetylene in
the thermal decomposition study, although the presence of chloroacetylene
was suspected from Gas Chromatograph (GC) analysis but could not be con-
firmed by Gas Chromatograph-Mass Spectometer (GC/MS) due to experimental
limitations.

     The similarity in results obviously suggests that similar reactions
are occurring, i.e., a gas-phase free-radical mechanism.  It is well docu-
mented that hydrocarbon reactions proceed by mechanisms based primarily on
attack of molecular species at low temperature (3,8).  At temperatures
between 250 and 450C, a peroxide-dominated mechanism appears to be active.
Above 450C, transition to a free-radical mechanism usually occurs.

     The "knee" in the thermal decomposition profiles generated on the IDAS
(Thermal Decomposition Analytical System) and TDU-GC (Thermal Decomposition
Unit-Gas Chromatograph) denotes the region of transition from a relatively
slow to a much faster reaction mechanism, e.g., transition from a peroxide
to a free-radical mechanism (see Figure 2 for example).  Detailed kinetic
calculations for propane indicate a rapid increase in the concentration of
the free-radical pool, predominantly OH, 0, and H, in the temperature range
of the knee (see Figure 2).  We have also performed pseudo-equilibrium
calculations for other more complex molecules, which also demonstrate a
rapid increase in radical concentration in this region.  This temperature
range of 500C to 700C is also appropriate for unimolecular decomposition
reactions to become significant.

     Some resarchers have questioned the contributions of surface reactions
or "wall effects" on flow reactor studies.  We have compared the results of
the extended gas-phase kinetic model for propane oxidation with results
from the TDU-GC.  This kinetic model has previously been compared to re-
sults from shock-tube studies and shown to be in excellent agreement (9).
As can be seen from the graph In Figure 3, the agreement between this
purely gas-phase kinetics model and our flow reactor study is excellent,

                                     9.

-------
     TABLE 3.  PICs FOUND IN DIFFUSION  FLAME  COMBUSTION OF CHLOROBENZENE,
             BENZENE, AND HC1 MIXTURE AND THERMAL DECOMPOSITION OF A MIXTURE
                    OF CARBON TETRACHLORIDE,  TOLUENE,  CHLOROBENZENE,
                           TRICHLOROETHYLENE,  AND FREON 113
                                               PICs From:
                              Flame-Mode  Combustion
               Thermal  Decomposition
                                    Mixture  1
                   Mixture  2
Anthracene
Benzofuran
Biphenyl
Biphenylene or Acenaphthalene
Chloroace tylene
Chloroanthracene
Chlorobenzene
Chlorobiphenyl
Chlorobiphenylene
Chloronaphthalene
Chlorophenylacetylene
Chlorostyrene
Chlorotoluene
Dichloroanthracene
Dichlorobenzene
Dichlorobiphenyl
Dichloronaphthalene
Dichloromethylstyrene
Dichlorostyrene
Dichloroacetylene
Dibenzofuran
Fluoroanthene
Methylnaphthalene
Naphthalene (or Azulene)
Phenylacetylene
Phenol
Phenylnaphthalene
Pyrene
Styrene
Tetrachloribiphenyl
Trichlorobiphenyl
Trichlorobenzene
Toluene
x
x
x
X
X
X

X
X
X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X

X

X
X
X
X
X
X
X
X
X
X
X
X
X
                                                              X
                                     10.

-------
    -3
    -5
 1/3
 LJ
 _J
 O
 21
 CD
 O
    -9
   -11
    13
     100
               D -
               A - CK

               -f- - o
800
900         1000
TEHPERRTURE IK )
1100
1200
Figure 2.  Concentration  vs.  temperature for propane oxidation

           in air at  a  gas-phase  residence time of 2.0 seconds.

-------
NJ
                   CD
                   ct
                   T.

                   UJ
                   LJ
                   cr.
                   CD
                   o
                    -3
                     -M
Experimental




Computer Prediction
                                500
            600       "700       800
                TEMPERRTURE 10
300
1000
             Figure  3.   Comparison of flow reactor  generated thermal  decomposition

                         profile versus predicted  results from computer-modeled gas-

                         phase free-radical mechanism for propane oxidation.

-------
especially in predicting the 199.99(2).  The slightly faster rate of
decomposition predicted by the model in the knee of the curve is likely
due to inaccuracies in the model in accounting for reactions involving
peroxides.  This is not unexpected since the model was developed for a
higher temperature region, where free-radical mechanisms dominate.  The
agreement between the flow reactor study and the gas-phase free-radical
kinetic model indicates that the mechanism of propane degradation in the
TDU-GC is truly a gas-phase, free-radical pathway at higher tempera-
tures .

     There is clearly a demonstrated correlation between flame-mode
and non-flame flow reactor POHC and PIC data.  This is due to free-
radical, decomposition reactions being operational in both instances.
The marked agreement in PIC identities, even for dissimilar feed mix-
tures, further illustrates the importance of the free-radical mechanism.
The majority of the products are due to recombination of free-radical
fragments or radical addition to aromatic substrates.  The lack of
oxygen-containing products even under oxidative conditions suggests that
abstraction of H by OH and 0 dominate over addition reactions.   Alter-
nately, addition products such as phenols may be very reactive  and rapidly
undergo further degradation.

     The main experimental difference in the flow reactor and flame studies
is the higher temperature in the flame which accelerates the overall reac-
tion rate, but apparently does not result in a change of mechanism.  Thus,
relative POHC DEs and PIC identities are very similar for both  cases.

CORRELATION OF LABORATORY PREDICTIONS AND FIELD RESULTS

     Of course the ultimate test of the study of the utility of laboratory
research is the degree of agreement between experimental or theoretical
predictions and actual field results.

     It was felt that a comparison of various proposed scales of inciner-
ability with recently available field test results would be useful.  If
areas of agreement or disagreement could be identified, then consider-
able guidance could be gained for the direction of future research.  This
study, which required considerable time and effort, was quite successful.
A summary of the results are reported in the following paragraphs.

     Six methods of ranking the relative incinerability of hazardous
organic compounds have been previously proposed (1,2,4,7,10-14).

     "  Heat of Combustion (AHc/g)
     *  Auto-Ignition Temperature (AIT)
     *  Theoretical Flame-Mode Kinetics (TFMK)
     "  Experimental Flame Failure Modes (EFFM)
     *  Ignition Delay Time (IDT)
     *  Gas-Phase Thermal Stability [Tgg(2) (99% destruction at 2 seconds
        residence time), TSH102 (High oxygen concentration), TSLo02 (Low
        oxygen concentration)]
                                      13.

-------
      The gas-phase thermal stability method has been proposed based on the
 results of flow reactor studies-  One method of ranking that has been pre-
 viously proposed is based on laboratory-determined thermal stability speci-
 fied by the temperature required for 99% or 99.99% destruction at 2.0 seconds
 reactor residence time in an atmosphere of flowing air [Tgg (2)] (1,14).
 This scale was originally developed for pure compounds in flowing air.  How-
 ever, recently generated data have shown that relative stability varies as
 a function of the composition of the waste feed and oxygen concentration
 [4].  This has led to modification of the rankings to account for the thermal
 stability of individual POHCs fed as a mixture in both an oxygen-rich
 (TSHi02) and an oxygen deficient (TSLo02) environment.  These three hier-
 archies along with the predictions of the other five, have been applied to
 predicting results of studies described in the following paragraphs.

      Intercomparison of field and laboratory data should be conducted with
 extreme caution.   While laboratory studies are usually conducted under
 precisely controlled well-defined conditions,  field studies generally are
 not (2,4,  14,15).  Upon examination of field study reports, it is obvious
 that the quantitative intercomparison of the performance of the facilities
 with respect to operational parameters is not  viable.  However, relative
 ORE data for POHCs within a waste feed at a given facility can be analyzed
 with proper data validation guidelines.   To ensure a valid comparison of
 predicted  and observed results,  the following  data validation and reduction
 criteria were used:

      *   only compare POHC DREs  (Destruction and  Removal Efficiencies)  for
         a  given incinerator

      *   only compare POHC DREs when they are fed to the system
         at a common point

      *   use  averages  of DREs when no significant run-to-run variation
         in relative  POHC ORE is  observed

         only use  data where the  majority of the  POHC DREs  are less  than
         99.995%

         include data  from non-concurrently fed POHCs if other key para-
         meters  are held constant

         conduct the  correlation  of  observed field  vs.  predicted results on
         a  rank/order  basis  with  a minimum of four  data points.

     The observed incinerability rankings  of the test compounds  at  each
source were compared with  the prediction of  each proposed  hierarchy  using a
rank/order correlation  approach  (16).  This method was  judged  to  be  superi-
or to a  linear regression analysis  since  the latter judges the  agreement of
the data with a best-fit  straight line while the former simply determines
if a statistically significant relationship  exists  between the observed and
predicted rankings.  The  rank-correlation  coefficient, rs, was used to
judge if a correlation existed at the 90%  confidence level for a number of
test compounds, N.

                                     14.

-------
                       TABLE  4.  RESULTS  OF  STATISTICAL ANALYSES  OF  OBSERVED  VERSUS
                                  PREDICTED  THERMAL  STABILITY  RANKINGS
Study
A
B
C
D
E
F
G
H
I
J
// Of
// Of
H
-0.
-0.
-0.
-0.
0.
0.
0.
-0.
-0.
-0.
Successes
Failures
% Success*
r/g
300/51
190/8
500/5
100/9
589/7*
343/15
400/4
333/7
077/10
291/10
1
9
10
AIT
-0
0

-0
0
0

0
-0
0



.200/4
.200/4
—
.060/
.428/6
.571/7*
—
.457/6
.262/8
.147/8
1
8
11
TFMK

—
—
—
—
-0.100/5
—
—
0.600/4
0.800/4*
1
2
33
Helrarchy
EFFM

—
—
—
—
—
—
—
0.600/4
0.600/4
0
2
0
IDT

—
—
—
—
—
—
-0.300/4
-0.100/5
-0.100/5
0
3
0
T99(2)

-0.057/6
0.500/5
-0.800/4
-0.300/5
-0.425/9
0.800/4*
-0.161/7
-0.217/9
-0.202/9
1
8
11
TSH102
0.
0.
0.
0.
0.
0.
0.
-0.
-0.
-0.



000/5
533/10*
400/5
386/9
425/8
041/15
800/4*
036
318/11
114/11
2
8
20
TSLoO?
0.900/5*
0.529/10*
0.600/5
0.493/9*
0.429/8
0.073/15
0.900/4*
0.655/8*
0.536/11*
0.523/11*
7
3
70
Correlation was statistically significant  at  the  90%  confidence  level

-------
     Results of this analysis are summarized in Table 4 for ten studies
 judged  to meet the data validation criteria (15,17-22).  Of the eight
 proposed ranking methods, only£Hc/g, AIT, T99 (2), TSHi02, and TSLo02
 had a sufficient data base to make predictions for a significant number  of
 sources.  Of these, only the experimentally predicted order under  low  oxy-
 gen conditions, TSLo02 met with a reasonable success, i.e., 70%.   The  other
 four methods only correlated with field observations 10-20% of the time.
 More importantly, it was apparent after detailed examination of the indi-
 vidual  data plots that certain trends were occuring that could not be  ex-
 plained by simple application of the ranking methods.  In particular,  the
 compounds that deviated in stability from predictions of the TSLo02 hier-
 archy were often the same for the various studies.  In many cases, this
 deviation could be explained using other available information.

     The paragraphs that follow discuss the data from the specific sources
 in a manner that demonstrates how the field-scale observations can be  re-
 liably  predicted with modifications to the TSLo02 hierarchy.

     Study A.  The test compounds followed the order of stability:   toluene
 > methyl ethyl ketone > 1,1,1-trichloroethane > Freon 113.  The observed
 order was the same as predicted by TSLo02 except for reversal of 1,1,1-
 trichloroethane and Freon 113.   In actuality, both of these compounds  are
 predicted to be relatively very fragile under low 02 conditions, and the
 predicted rankings could have been easily reversed.  The predicted rankings
 as pure compounds in flowing air or in a mixture of high 02 were quite
 different and did not correlate with the observations.  This is consistent
 with the low 02 levels noted in the field study reports.

     Study B.  The predictions  of the TSLo02 method and the observed sta-
 bilities agreed quite well with only a few exceptions.  Chlorobenzene  and
 dichlorobenzene were observed to be reversed from the predicted order.
 This is readily explained by the observation that significant levels of
 chlorobenzene were detected in the scrubber make-up waste and could be
 stripped out and into the stack gases.   This would result in an apparent
 chlorobenzene DRE lower than actually achieved by thermal destruction  and
 account for the disparity with  the TSLo02-   A major deviation was  observed
 for bis-2-ethyl-hexyl phthalate, which appeared more stable than predicted.
 Although the predicted stability of phthalate is questionable due  to lack
 of laboratory data,  phthalates  are ubiquitous and detected levels  may  be
 due to out-gassing of plastics  in the system and not from undecomposed
 feed.   High levels of phthalates are commonly found in ambient environments
 and for this reason should probably be excluded from all data sets  (23).
 Bis-2-ethyl-hexyl phthalate was found at high levels in the scrubber water.
 Stripping from the water by the effluent gas could account for its  observed
 emissions.

     Two other major outliers were aniline and trichloroethylene.   These
 compounds were significantly more fragile than predicted.  Neither  aniline
nor trichloroethylene would be  expected to be a major thermal reaction
 product from this  test sample.    This is in contrast to chloroform, carbon
 tetrachloride,  and phosgene,  which unexpectedly surpassed aniline and tri-
 chloroethylene  in apparent stability.  The apparent thermal stabilities of

                                     16.

-------
carbon tetrachloride, chloroform, and phosgene may be due  to  their forma-
tion as products  from other components  of  the waste  as  opposed  to their
stability as POHCs.  Furthermore, these  compounds are quite volatile and
could be present  in the ambient air  as  fugitive  emissions.  Either forma-
tion as a product or as an ambient air  contaminant could explain the un-
expected reversal in thermal stability.

     Study C.  The waste was spiked  with theroretically stable  POHCs which
had an observed order of stability:  acetonitrile >  benzene > trichloro-
ethylene > chlorobenzene > carbon tetrachloride.  This was as expected
except for benzene which was considerably  more stable than predicted based
purely on thermal stability.  It is  possible that benzene was formed as a
product from chlorobenzene (or the auxiliary fuel).  This hypothesis is
supported by two  independent observations.  First, a simulated waste stream
very close in composition to the actual  waste was subjected to  thermal
decomposition in  the laboratory.  Under  low 02 conditions, benzene would
actually have been predicted as a reaction product resulting in a low
apparent DRE for  benzene as a POHC.  Secondly, the waste stream was also
fed to the full-scale incinerator without  benzene in the feed.  Roughly
equivalent levels of benzene were found  in the stack effluent, thus con-
firming the hypothesis that its emission was due to  sources other than
residual POHC from the waste feed.

     Study D.  Field test results were  in  basic agreement with prediction
for low oxygen conditions.  The exceptions were phthalates, which were
discussed previously, and tetrachloroethylene, which was predicted to be
the most stable component but was observed to be less stable than benzene,
toluene, naphthalene, carbon tetrachloride, and methyl ethyl ketone.
Laboratory studies have demonstrated or  strongly suggested that each of
these compounds can be a significant reaction product from various pre-
cursors (A,17,24).  Dichloromethane  and  chloroform were also found in the
source emissions, suggesting the formation of chlorinated methanes as
thermal reaction products.  Thus, the apparently greater stability of these
compounds than tetrachloroethylene may be  due to their formation as pro-
ducts in the incineration process.

     Study E.  A. correlation was observed  between predicted and observed
rankings but there was significant scatter.  The fragile nature of 1,1,2-
trichloroethane, 1,1,1-trichloroethane,  and methyl ethyl ketone were
correctly predicted (DREs all at 99.999% or greater).  The observed sta-
bility of these three compounds were permuted from their predicted value
contributing to the poor correlation coefficient.

     Methylene chloride, and to some extent, carbon  tetrachloride appeared
more stable than predicted.   It should be  noted that high levels of other
halogenated methanes were found in the stack effluent indicating a source of
carbon tetrachloride and methylene chloride emissions other than residual
POHC (i.e., either incomplete combustion products or a result of stripping
of these volatiles from the scrubber water).  The most unexpected behavior
was exhibited by tetrachloroethylene, which was predicted to be the most
stable POHC but was observed to be very  fragile.
                                     17.

-------
     Study F.  Although this facility exhibited the lowest correlation  of
predicted and observed emissions, the results are extremely informative.
Two distinct groups were evident, one consisting of primarily chlorinated
aromatics and olefins, and a second consisting of primarily halogenated
aliphatics along with bis-2-ethyl-hexyl phthalate and hexachlorocyclobuta-
diene.

     Methylene chloride and chloroform were found in the scrubber make-up
water which could readily account for their observed emission levels.   The
other halogenated compounds (in the second group) are also very volatile
and have been found in the ambient air surrounding such facilities  (pre-
sumably due to fugitive emissions) (15).  As previously discussed,  phthal-
ate emissions are consistently high at most sources.  Finally, there is
some question concerning the accuracy of the predicted ranking for  hexa-
chlorocyclopentadiene due to lack of laboratory data.  Its low stability
prediction was based on possible strain of the five numbered ring structure,
but could well be in error.  If the six compounds in question are eliminated
from the data set and a correlation is performed with the remaining nine
compounds, a statistically significant rank correlation coefficient of  0.89
is obtained.

     Study G.  The observed stability is as predicted under low Q£  con-
ditions except for carbon tetrachloride which appeared more stable  than
chlorobenzene.  This is not surprising since chloroform, which was  also
present in the mixture of carbon tetrachloride, has been established as a
thermal reaction product of chloroform by laboratory studies.

     Study H.  The POHCs in this test essentially followed the predicted
order except for tetrachloroethylene and trichloroethylene, which appeared
less stable than benzene and toluene, contrary to predictions.  This type
of result has been observed in other studies and is ascribed to the propen-
sity for formation of toluene and benzene as reaction products.  It is  also
interesting to note that carbon tetrachloride emissions were also quite
high (average of 173 g/s) which tends to confirm its prevalence as  a reac-
tion product from incineration of chlorinated wastes.

     Study I.  The observed POHC stabilities followed predicted trends
except for benzene, carbon tetrachloride, and 1,2-dichloroethane.   Benzene
and carbon tetrachloride are again expected to be products of thermal
degradation (primarily from chlorobenzene/toluene and methylene chloride
respectively).  The 1,2-dichloroethane is a volatile compound that  is
commonly found in scrubber water or in the ambient air as a fugitive
emission, factors which could account for its elevated emission level (15).
The emission level of 1,1,1-trichloroethane, also sometimes found as a
fugitive emission or in scrubber makeup water, was also slightly elevated.

     Study J.  The observed deviations from the predicted rankings were
similar to those observed for the previous nine cases.   Benzene, toluene,
and carbon tetrachloride emissions were higher than expected, an observa-
tion which is attributed primarily to product formation.
                                    18.

-------
Discussion  of  Laboratory/Field  Comparisons

     The  degree  of  success,  as  indicated  by  the  results  reported  in  Table
4 and  the subsequent  discussions  of  predicting the  relative  thermal
stabilities of hazardous  organics through laboratory  flow reactor studies
may appear  somewhat surprising  considering the complexity of  the  incinera-
tion process.  However, the  development of the two-zone  incineration model,
which  was discussed earlier  illustrates how  post-flame chemistry  controls
incinerator emissions  and is  sufficient to explain  general agreement between
laboratory-based  predictions  and  field results.  However, none of  the
previously  presented  incinerability  hierarchies  directly address  the issue
of PIC emissions  as they  are  only concerned  with thermal stability of the
POHCs  in  the feed material.

     PICs resulting from  the  incineration of hazardous waste  are  not
currently regulated by the USEPA.  However,  the  previously discussed field
data and  results  of other laboratory, pilot, and  full-scale  testing pro-
grams  have  shown  that  toxic  products can  be  formed  and are emitted from
incinerators (3,4,17-24).  Many observed  PICs are also potential  POHCs,
consequently,  it  is entirely  possible that a PIC may  also be  a POHC in the
original mixture.   Three  documented  examples are:   the formation  of carbon
tetrachloride  from  chloroform, and from hexachlorobenzene from hexachloro-
cyclopentadiene,  and  benzene  from chlorobenzene  or  toluene (4,17,24).

     In the previous  discussion of field  results many such cases were
identified.  This gave rise  to low apparent  DRE  for the  POHC.  Since this
effect would be more  important when  the input concentration of the POHC is
low, the  result would  be  an  apparent dependence  of DRE on input POHC con-
centration  (i.e., the  higher  the  input concentration, the greater the
apparent DRE).  The true  effect,  however, is that the emission concentra-
tion is constant, since the  emissions are probably  due to product formation
from other  waste  components.

     The observation  of an apparent  DRE dependence  on concentration has
been made for  hazardous waste incinerators and attributed to  greater than
first  order kinetics  for  indivudal POHCs  (15).  While such an effect could
be possible for combustion of a pure compound, it is highly improbable when
the POHC is only a  small portion  of  a complex waste.  The reaction chemistry
is determined  by  the overall waste and fuel composition  as opposed to pure
compound kinetics.  Volatile POHCs in the ambient air as a result of fugi-
tive emissions, volatile POHCs stripped from scrubber waters, and out-gas-
ing of phthalate-containing materials would also give rise to apparent
concentration  dependencies since  their emission  levels would  be constant
while  the POHC input rate varies.  Specifically; it has  been  shown earlier
that most of the observed deviations from laboratory  predicted rankings of
incinerability may  be attributed  to  product formation or "contamination" of
the stack effluent  by volatile POHCs that did not pass through the destruc-
tion zones of  the incinerator.

     As if  predicting POHC stability were not difficult  enough, we must now
predict product formation.  This  can be accomplished  perhaps  by laboratory
thermal decomposition testing of  the actual waste stream to be incinerated,

                                     19.

-------
or a very close simulation.   As indicated by the agreement of laboratory
predictions based on low C>2 conditions,  these studies should be conducted
under pyrolytic conditions.

     An excellent example of this approach is Study C.  The incinerability
ranking based purely on POHC ORE was successful for four out of the five con-
stituents of the waste, only benzene being apparently more stable than the
other components.  However,  laboratory testing was performed on a very similar
waste stream and under pyrolytic conditions;  significant levels of benzene
were were observed.  Thus, when product  formation is included,  laboratory
testing of a simulated waste stream could correctly predict the observed
field results.

Summary And Conclusions Regarding Laboratory/Field Comparisons

     The results of comparison of ten field studies with thermal stability
predictions indicates that  no ranking based on pure compound properties can
provide an appropriate scale of incinerability.   However,  a ranking based on
predicted POHC stability in complex mixtures  under low oxygen conditions gave
a statistically significant  correlation  with  field results in seven of ten
cases.  More importantly, analysis of results gives strong reason to believe
that formation of "POHCs" in the incineration process as PICs may be respon-
sible for their observed DREs.

     Pending further confirmatory comparisons with field results, the
following conclusions are proposed.

     •  Measured POHC DREs  and relative  stabilities of all but  the most
        stable  compounds are due to  formation as  products  from  other com-
        ponents of the waste fuel or feed.

     *  Only DREs for very stable POHCs,  or POHCs difficult to  form as
        reaction products (e.g., acetonitrile),  are expected to be unaffec-
        ted by  PIC formation and these stabilities are predictable from
        pure compound thermal decomposition kinetics.

        The stack emissions  and observed DREs of  the very  volatile com-
        pounds  (e.g., methylene chloride,  chloroform, di-  and trichloro-
        ethanes) may be dominated by fugitive emissions in the  ambient air
        or stripping of these compounds  from  contaminated  scrubber water.

        Thermal decomposition,  not in-flame destruction determines relative
        POHC DREs and the identity and yield  of  products of incomplete com-
        bustion.

     *  Pyrolytic conditions in the  incinerator  are responsible for most
        emissions  and control the  relative  DREs  of POHCs and the  formation
        of  products.

        Predictions  from laboratory  thermal decomposition  testing of
        pure  compounds  and mixtures  can  be  effectively used  to  predict
        relative  POHC DREs.

                                     20.

-------
        Laboratory  testing under pyrolytic  conditions on  actual waste
        streams or  closely simulated waste  streams  is an  effective
        and  reliable method for predicting  relative POHC  stabilities
        and  PIC emissions.

     EXPANSION OF DATA BASE ON POHC STABILITY AND PIC FORMATION FOR PURE
     COMPOUNDS AND  MIXTURES

     The  success in predicting the results  of field studies from labora-
tory experimentation shows the utility  of the laboratory  approach but also
points out the need for  a larger data base  from which to  predict the effect
of changing  reaction atmosphere and waste composition.

     The  results of four early experimental studies are detailed in the
following paragraphs.

          Thermal Decomposition of "CRF Soup - 1"*

          In our most ambitious laboratory  study to date, the thermal
degradation  of a mixture of five hazardous  organic  compounds under a
variety of conditions was investigated.  The mixture was  studied in three
reaction  atmospheres:  oxygen-starved,  stoichiometric oxygen, and oxygen-
rich.  The behavior of the components in the mixture was  compared to their
behavior  when tested as  pure  compounds  and  the thermal reaction products
were identified.  Thermal decomposition behavior was analyzed and related
to elementary chemical reaction kinetics.

     The  observed thermal stabilities for the test compounds for each
experimental condition are summarized in Table 5.  As can be seen from
these results, considerable differences in  absolute and relative thermal
stabilities  were observed as  a function of  both oxygen content (specified
as the equivalence  ratio, 
-------
     TABLE 5.  SUMMARY OF THERMAL DECOMPOSITION TESTING FOR
                 COMPONENTS OF HAZARDOUS WASTE MIXTURE #1
                                                        T99  (2)  ("O
                           T99 (2) (°C) for HWM-1      Pure  Compounds

POHC          A Hr/g      j>-0.06 <|)=1.0    Pyrolysis
Freon 0.11
Carbon tetrachlori.de 0.24
Trichloroethylene 1.74
Chlorobenzene 6.60
Toluene 10.14
770
670
730
730
670
780
680
780
800
750
780
680
920
>1000
820
780
750
800
900
820
780
750
780
700
680
                               22.

-------
measured  thermal stabilities will  also vary with changing reaction atmos-
sphere.   The lower concentration of H atoms (and somewhat lower reactivity
versus OH and 0) results  in slower destruction rates for the three aromatic
compounds at reduced oxygen levels, while Freon 113 and carbon tetrachlor-
ide are relatively unaffected.  For these reasons, relative POHC thermal
stabilities are observed  to change as a  function of .

     Benzaldehydes, phenols, and benzofurans were the only observed oxidation
products  under oxidative  or pyrolytic conditions while numerous complex
pyrolysis type products were observed (see Table 6).  This indicates that
most products result from recombination  of radical fragments and OH and 0
addition  products are not significant.   The lack of addition products
suggests  that OH and 0 may be more likely to participate in abstraction
reactions at high temperatures or  that the intermediate addition products
are not very stable.  This is clearly an area for further research.

     In that same study,  the thermal degradation of carbon tetrachloride and
Freon 113 were observed to be independent of the oxygen content of the re-
action atmosphere, while  trichloroethylene, monochlorobenzene, and toluene
decomposed more readily as the oxygen concentration was increased (see
Figure 4  for example).  This behavior is predictable based on chemical
kinetic considerations as previously discussed.  It is also interesting to
note that Freon 113 (a previously  proposed tracer) was not observed to be
very stable.  The relatively fragile nature of Freon 113 has recently been
confirmed by pilot and field studies [30,31].

     Formation of PCDFs and other  PICs from PCBs

     The  thermal degradation of a  single PCB isomer was conducted under
four reaction atmospheres at a constant gas-phase residence time of 2.0
seconds.  The isomer selected for  study was 2,3 ' ,4,4',5-pentachloro-
biphenyl  (2,3 ' ,4,4 ' ,5-PCB).  The oxygen  availability in the reaction atmo-
sphere was again described using the equivalence ratio .  The values of $
used in this study were 3.0, 1.0,  0.2, and 0.05 which range from oxygen
starved to very oxygen rich conditions as the values of  become progres-
sively smaller.  Thermal  degradation experiments were conducted at various
temperatures ranging from 500-1000C.

     Table 7 lists the major thermal reaction products tentatively iden-
tified for the thermal degradation of 2,3',4,4',5-PCB.  A variety of pyro-
lysis and partial oxidation products were formed, with polychlorinated
dibenzofurans (PCDF) congeners representing the majority of the oxidative
products.  Significant quantities  of partially dechlorinated biphenyl
congeners were formed along with dichlorobenzenes and trichlorobenzenes.
Tetrachlorobiphenylene isomers were also observed.  These are of particular
interest due to their suspected toxicity.  The formation of trichloronaph-
thalene is important because of its apparent thermal stability.  At 1000C
for |> = 1-0, the reaction product  tentatively identified as tetrachloro-
naphthalene exceeded the concentration of the remaining parent PCB.  As one
might expect, the yield of pyrolysis products decreased with increasing
oxygen levels.   However, the increase in PCDF concentration with increase in
oxygen concentration was far more  striking.

                                     23.

-------
TABLE 6.  REACTION PRODUCTS OBSERVED FROM
      THE THERMAL DECOMPOSITION OF CRF SOUP-1
Formula
CHC13
C2H3C1F2
C2H2C12
C2C13F
C2C14
^-*4 4 2
C^HA
C6H6

C6H60
C6H5F
C6H5C10
C6H4C12

C6H4C12
C7H80
C7H7C1
C7Hg02

C7H60
C8H].o
C8H8
C8H7C1
C8H6
C8H6C12


C8H6C1F
C8H6F2
C8H60
C8H5C1
C8H5C13
C8H5C10
C8H5F3
C9Hg
C9H8C12


C9H80
C9H7C13
C9H7C10
C9H60
C10H8
Identification =0.06 <|>=1.0
Tri chlor ome thane
Chlorodifluoroethane
1 , 1-Dichloroethene
Trichlorof luoroethene
Tetrachloroethene
Dichlorobutadiene
Benzene
1,5-Hexadiyne
1 , 5-Hexadi en-3-yne
Phenol
Fluorobenzene
Chlorophenol
Dichlorohexadiyne
Dichlorohexadiene-yne
Dichlorobenzene
Methylphenol
Chloromethylbenzene
Hydroxy-benzaldehyde
Benzodioxol
Benzaldehyde
Ethylbenzene
Ethenylbenzene (Styrene)
Chloroethenylbenzene
Ethynylbenzene
Dichloro-ethenylbenzene
Chloroethenyl-chlorobenzene
Di Chloroethenylbenzene
Chloro-f luoroethenyl-benzene
Difluoro-ethenylbenzene
Benzof uran
Chloro-ethenylbenzene
Trichloroethenylbenzene
Chlorobenzofuran
?
IH-indene
Dichloro-propenylbenzene
Dichloropropylbenzene
Chlor opropenylchlorobenzene
Phenyl-propenal
?
Chi orome thy Ibenzof uran
Phenylpropynone
Azulene
X

X



X
X

X

X


X
X
X
X

X
X
X
X
X
X




X

X
X


X


X


X


X
X
X
X
X
X
X

X
X
X
X

X
X
X


X
X
X
X
X
X


X
X
X


X

X




X
X

X
Pyrolysis


X
X


X
X

X
X





X



X
X
X
X
X


X
X

X

X
X
X
X



X


X
 Naphthalene
 Methylene-lH-indene
                  24.

-------
                           TABLE 6. - Continued
Formula
                         Identification
ij)=0.06    «)>=1.0    Pyrolysis
C10H8C1F
C10H7C1
C10H6C12
C10H5C13
C11H10
C11H10
C11H10
C13H802
C14H14

Cl4H12


C14H12


C14H10



C14H100

C14H9F
C15H2
C16H12
C16H12
Chloronaphthalene
Dichloronaphthalene         x
Trichloronaphthalene        x
1-Methyl-naphthalene
2-Methyl-naphthalene
Methyl-naphthalene
Biphenyl
Dibenzofuran                x
1,1-Methylene(bis)-benzene
9H-Fluorene
Diphenylmethanone            x
9H-Xanthen-9-one             x
1,!'-(!,2-ethanediyl)(bis)-
  benzene                    x
MethyIfluoroene
1,!'-(!,2-ethenediyl)(bis)-
  (E)-benzene
Dihydrophenanthrene          x
1,!'-(!,2-ethynediyl)(bis)-
  (z)-benzene
1,!'-(!,2-ethynediyl)(bis)-
  benzene                    x
Phenanthrene
9-Methylene-9H-fluoroene
Anthracenone                 x
Penanthrenol
Fluoro-l,l'-(12,-ethyne-
  diyl)(bis)-benzene
Fluorophenanthrene
Fluoromethylene-9H-fluoroene
7
Methyl-anthracene
Methyl-phenanthrene
2-Phenyl-lH-indene
9-Ethylidene-9H-fluoroene
1,4-Dihydro-l,4-ethenoanthracene
1-Phenyl-naphthalene
5-Methylene-5H-dibenzo[a,d] cyclo-
  heptene
2-Phenyl-naphthalene
Fluorophenylnaphthalene
Fluoro-5-me thylene-5H-dibenzo[a, d ]-
  cycloheptene
Fluoro-1,4-dihydro-l,4-etheno-
  anthracene
             x
             x
                                                           x
                                                           X
                       X
                       X
                       X
                       X
                       X
                                                                     X

                                                                     X
                       X

                       X
                                                                     x
                       x
                       x
                                      25.

-------
                           TABLE 6. - Continued

Formula	Identification	£=0.06  <|)=1.0   Pyrolysis


^16^11*"              Fluorophenylnaphthalene
C16H10               Pyrene                                           x
                     Fluoroanthene
C16H10C1F            ?                                                x
                     Fluoropyrene                                     x
                     Fluorofluoroanthene
                     HH-Benzo[a]fluorene                             x
                     HH-Benzo [b]f luorene
                                    26.

-------
  100
CD
LU
   10
  o.i
LU
 0.01
          TOLUENE
        '  *  1.0
        °  PYROLYSIS
     0      200     400     600     800    1000
                 TEMPERATURE (°C)
  100
CD
LU
    0
S2  O.I
LU
  0.01
FREON 113
  = 0.66)
           and  stoichiometric air (([> = 1.0),  and
           absolute pyrolytic conditions for  gas-
           phase  residence times (tr) of 2.0  seconds
                      27.

-------
  TABLE  7.  MAJOR REACTION PRODUCTS TENTATIVELY  IDENTIFIED FROM
    THE  THERMAL DEGRADATION OF 2,3',4,4',5-PENTACHLOROBIPHENYL
                                                  Number of
	Product Class	Major  Peaks

Tetrachlorodibenzofurans                               2

Trichlorodibenzofurans                                 2

Pentachlorodibenzofurans                               1

Tetrachlorobiphenyls                                   5

Trichlorobiphenyl                                      1

Trichlorobenzene                                       1

Dichlorobenzene                                        1

Trichloronaphthalene                                   1

Tetrachloronaphthalene                                 1

Trichlorophenylethyne                                  2

Dichlorophenylethyne                                   1

Tetrachlorobiphenylenes                                2

C9H8OC1                                                1

C10H3C13                                               1
                               28.

-------
     Table 8 presents  the yields of observed PCDFs  at various  equivalence
ratios.  As the oxygen concentration  increased by a factor of  60, the yield
of total PCDFs increased by a  factor  of  7.  The percentage of  total PCDFs
identified as tetra  isomers ranged from  62-72%.  Thermal formation/
destruction profiles for observed PCDFs  for  = 1.0 are depicted in Figure


     As can be seen  from the data in  Figure 5 the degradation  rate of
2,3',4,4',5-PCB rapidly increases above  approximately 750C.  This is in
the region where  one would expect a transition from a peroxide-dominated
reaction mechanism to a free-radical  mechanism.  Pseudo-equilibrium calcu-
lations of the concentration of small reactive species indicate that the
concentration of  reactive radicals increases rapidly between 700C and 900C.
Since incorporation  of oxygen  is necessary for the  formation of PCDFs from
PCBs, OH and 0 are implicated  as the  predominant reactive species responsi-
ble for PCDF formation.

     For all but  the most fuel-rich systems and temperatures between 700C
and 1000C, the OH concentration is calculated to be roughly a  factor of 10
greater than the  0 concentration, which  is in turn a factor of 1000 to
10,000 greater than  the H concentration.  Thus, OH would appear to be the
major reactive radical under either stoichiometric or oxygen-rich con-
ditions.  When the equivalence ratio  increases, the OH and 0 concentrations
decrease as the H atom concentration  increases.  This shift in equilibrium
to non-oxygen containing radicals results in a decreased yield of oxygen-
ated products such as PCDF.  Thus, for large equivalence ratios, larger
yields of pyrolysis  products (e.g., polychlorinated benzenes, PCB congen-
ers, chlorinated  naphthalenes, chlorinated biphenylenes, etc.) are obser-
ved.  Although H atoms are usually considered to be the dominant reactive
radical in hydrocarbon systems under  pyrolytic conditions, the large con-
centration of Cl atoms in PCB  systems may result in Cl being the dominant
reactive species.  Additional  research on the role of Cl atoms is strongly
suggested.

     For the range of oxygen levels studied, the PCDF yield decreased with
equivalence ratio.  Although not addressed directly in this study; one
might expect the yields of PCDFs to start to eventually decrease with
increasing oxygen concentration due to enhanced destruction of the PCDF
product as it is oxidized to simpler  products including carbon monoxide and
carbon dioxide.  The shift in  the temperature for maximum yield of PCDFs as
a function of equivalence ratio is a  reflection of  the competition between
oxidation of PCB to form PCDF and oxidation of the PCDF itself.  The obser-
vation that the highest temperature of maximum PCDF yield is for <}> = 1.0
and decreases for <}> = 3.0 or  = 2.0, may well be due to the shifting con-
centrations of the species responsible for PCDF formation and  destruction.

     Potentially important elementary reactions for PCDF formation by OH
attack are shown in reactions  1 through  3.
                                     29.

-------
              TABLE 8.  MAXIMUM WEIGHT PERCENT YIELD OF PCDFs
                          AS A FUNCTION OF REACTION ATMOSPHERE


        Temperature of     	Weight % Yield      	

  >j)    Maximum Yield (C)   Tri-CDFS  Tetra-CDFS   Penta-CDFS   Total PCDFS

0.05         750             0.66        4.3          2.0          6.9

0.2          800             0.34        1.7          0.56         2.6

1.0          900             0.13        1.3          0.25         1.7

3.0          850             0.068       0.71         0.21         0.99
                                     30.

-------
   100
o
cr
UJ
CL
    10
    O.I
  O.OI
            2, 3 ' ,4,4• .5-PC3
TOTikL-PCDFS



TE7RA-COFS








PENTA-CDFS





  TRI-CDFS
                  500     6OO     70O      800

                        EXPOSURE TEMPERATURE,°C
                           900
IOOO
          Figure 5.  PCDF formation/destruction profiles for

                     =1.0 and a gas-phase residence time of

                     2.0 seconds.
                                  31.

-------
                                                                :D
           ci
                                                 4-  H
                                                                (2)
                                                                (2'
(3)
                 H  0
     A mechanism involving reactions  1 and 2 would correspond to an HC1
elimination mechanism,  while as mechanisms involving reactions 1,  2, and 3,
would correspond to an H2 elimination mechanism.   Reaction 1 is shown as a
substitution reaction but may actually be an addition followed by H atom
elimination.

     Similar reaction mechanisms may  be drawn for 0 atom attack.  Reactions
4 and 5 would also result in H2 elimination.
                                                           (4)
                                                           (5)
Reaction schemes involving CI atom loss through addition or substitution
reactions would be expected to be energetically less favorable with lower
yields of PCDFs.  This would account for the lower observed yields of PCDFs
formed through a mechanism involving Cl2 elimination.

     The changes in yields of various products as a function of oxygen
level and temperature is very important for understanding the results of
PCS degradation.  For example, internal arcing in a sealed capacitor would
result in heating of PCBs in an oxygen-deficient environment.  Under these
conditions,  one would predict a shift of yields towards pyrolysis products
such as other PCBs,  polychlorinated benzenes (PCBzs),  and polynuclear aro-

                                    32.

-------
matics^(PNAs) rather than PCDF.  However, higher temperatures are required
to achieve conversion which may not be reached.  On the other hand, open
burning or combustion of the PCBs would occur in an environment with more
available oxygen which would favor the formation of oxidative products such
as PCDFs.  However, even under fire conditions, oxygen-starved conditions
can also exist resulting in formation of pyrolysis products.

     During incineration, one would expect that oxygen-deficient combustion
conditions would control the composition of the stack effluent.  For ther-
mal destruction processes that involve both flame combustion and thermal
oxidation, it is contended that only the fraction of the organic waste
which escapes the  flame and thus undergoes degradation in an oxygen-defici-
ent environment is responsible for most emissions.  Therefore, a well-
defined relationship for temperature and oxygen concentration effects on
PCB degradation and product formation can be used to guide the environmen-
tally safe incineration of PCB-containing wastes.

     Formation of  PICs from Chloroform

            The thermal decomposition profile of chloroform and the thermal
generation/decomposition profiles for two of its thermal reaction products
are plotted in Figure 6.  Pentachloroethane as a product is shown due to
its possible role  in the chloroform thermal decomposition pathway.   Tetra-
chloroethylene is  shown because of its high yields, exceptional thermal
stability, and toxicity.

     As shown in Figure 6, chloroform is a relatively thermally fragile
compound.  In a recent study by our laboratory, chloroform ranked second
from the last in terms of thermal stability (1).  It has also been shown to
be considerably less stable than dichloromethane and carbon tetrachloride.
Based on decomposition via homolysis of a C-C1 bond, chloroform would be
expected to be more stable than carbon tetrachloride.

     Studies by Shilov and Sabirova at temperatures ranging from 485-599C
led to the conclusion that the initial step of chloroform decomposition was
not simply C-C1 bond homolysis, but the direct loss of HC1 to form an
intermediate biradical dichlorocarbene (25).  The dichlorocarbene may then
further react with chloroform through insertion in the C-H bond to form
pentachloroethane  (26).  Another proposesd reaction of dichlorocarbene is
its combination with another dichlorocarbene to form tetrachloroethylene.

     The thermal decomposition profile of pentachloroethane and the
generation/decomposition profile for the product tetrachloroethylene are
shown in Figure 7.  As shown, pentachloroethane and chloroform are of
comparable thermal stability.  The conversion of pentachloroethane to tetra-
chloroethylene is very favorable and most likely occurs through the concerted
elimination of HC1 (27).  If chloroform decomposition does proceed via the
formation of pentachloroethane, then subsequent HC1 elimination from the
pentachloroethane would certainly contribute to the high yields of tetra-
chloroethylene observed.

     The products  identified (tentative structural assignments) from the

                                     33.

-------
 100
                                                        C2HCL5
0.01
     300
500             70O
Temperature (°C)
900
     Figure 6. Weight percent  (normalized to non-decomposed parent
              peak) vs. temperature for chloroform and selected
              decomposition products ( = 0.76, 2.0 seconds
              residence time).

-------
              100 Q
             10.0
U)
Ln
         g>  1.00
         (D
             0.10
            0.01
                                       D
                                       A
0
 L
C2CL4
          1
                 300
                 Figure 7.
        500             700
        Temperature (°C)
 900
Weight percent  (normalized to non-decomposed parent
peak) vs. temperature  for pentachloroethane and its
major decomposition product tetrachloroethylene
( = 0.76, 2.0  seconds residence time).

-------
thermal reaction of chloroform and pentachloroethane are listed In Table
9.  The similarity of the products supports the hypothesis of common
decomposition pathways.  Based on the observed products as well as the
previously mentioned studies, decomposition pathways as shown in Figure 8
may be envisioned.  Products listed in Table 9 which are not shown may be
generated by further elimination of HC1 and/or radical reactions.

     Formation of PICs from Polychlorinated Phenols

            The thermal decomposition of chlorophenols is of intense
interest because of the potential formation of polychlorinated dibenzo-
dioxins (PCDDs) as incomplete combustion products.  Thermal decomposition
data was obtained using the TDU-GC for pentachlorophenol (PCP) in nitrogen,
pentachlorophenol in air, and 2,4,5-trichlorophenol (2,4,5-TCP) in nitrogen.
Thermal decomposition profiles for these compounds are presented in Figure 9.
The extrapolated Tgg(2) is 640C for PCP in nitrogen, 630C for PCP in air,
and 775C for 2,4,5-TCP in nitrogen.

     Major products of incomplete combustion were identified for PCP in
nitrogen and in air using the TDAS.  These partial combustion products,
along with their temperatures of maximum formation, are given in Table 10.

     The similarity between the thermal stability of PCP in air and nitro-
gen suggests that unimolecular decomposition is a significant degradation
mechanism.  The oxygen-hydrogen bond energy in phenol is relatively low (88
kcal/mole) and may be lower in 2,4,5-TCP and lower yet in PGP-  Of course,
oxygen is available in the reaction atmosphere as a degradation product of
PCP and TCP, probably in the form of OH.  One would expect the hydroxyl
hydrogen to be susceptible to abstraction by OH.   From profiling the
combustion products,  it was observed that all were formed at approxi-
mately equal concentrations (within a factor of 10), at their temperatures
of maximum yield.  It was also observed that the  formation maxima for PICs
generally peaked at about 630C-650C for pentachlorophenol in air and 725-
775C for pentachlorophenol in nitrogen.  This is  interesting in light of
the fact that the parent material exhibited a maximum decomposition rate
between 625C and 650C in both cases.   This may have occurred because in air
PICs were forming directly from the parent material, while in nitrogen the
principal PICs may have evolved through thermal decomposition of other PICs.

     Table 10 includes only the major PICs observed at selected reaction
temperatures on the TDAS.  It should be noted that the production of octa-
chlorodibenzo-p-dioxin (OCDD) was tentatively identified by retention time
on the TDU-GC, and that this identification was confirmed by examining low-
level peaks on the TDAS.  The maximum yield in air (— 1%) was observed at
500C,  while the maximum yield in nitrogen (^1.5%) was seen at 550C.

     Expansion of Pure Compound Kinetic and Thermal Stability
     Data Base

     We have also generated additional pure compound thermal decomposition
kinetic data.  Tables 11 through 13,  are a complete listing of compounds
for which we have measured pseudo-first order oxidation kinetic parameters.

                                     36.

-------
TABLE 9.  THERMAL DECOMPOSITION PRODUCTS
                  OBSERVED FROM:
CHLOROFORM
 (CHCl.Q
  CC14
  C2HC13
  C2HC15
  C2C12
C4C14
                              PENTACHLOROETHANE
                                   CHC13
                                   CC14
                                   C2H2C14
                                   C2HC13

                                   C2C12
                                   C3H6C12
                                   C3C14
                                   C4H2C16
                    37.

-------
     CHCL3   £
                  CCL2 +  HCL
                            .CHCL
                                 HCL
                 C2HCL5
    CL-,  C9HCLa-  + CCLv   CHCLo-
                   I
CHCL3 +
           C2CL5 + C2HCL5
                      HCL
                C2HCL3
Figure 8.   Possible  pathways for the thermal
          decomposition of chloroform.
                  38.

-------
                                                                     I     I
  100 r
   10
o

z
UJ
o:

H
z
UJ
o

-------
        TABLE 10.  THEHHAL DEGRADATION PRODUCTS FROM PENTACHLOROPHENOL3
 Tentative Identification       Tentative Structure
 Dichlorobutadiyne
                        Temperature of
                     Maximum Formation (C)

                        In N?     In Air
                         800
                                                                     ND
Tetrachloroethylene
Tetrachloropropyne
Ck

Cl
                                          Cl
                                        Cl
                                         I
                                        Cl
                                                          ND
                                                          ND
                                                                    650
                                   630
Trichlorofuran
l,l,2,4-tetrachloro-l-buten-3-
        yne
Tetrachlorofuran
 Trichlorobenzene
                                 Cl
                                      -0
           Cl
                                    Cl     H
                                         Cl
                                         I   ..Cl
C'^P^CI
   Cl    Cl

     x^v   cu
                                                          ND
                                                          ND
                                                           625
                                                                    630
                         725        630
                                                                    650
                                                                     630
Tetrachlorobenzene
Pentachlorobenzene
           CL
           CI5
                                                           775
                                                          725
                                    630
                                                                     630
Hexachlorobenzene
                                                          725
                                                                     ND
                                     40.

-------
                              TABLE 10.  (Continued)
Tentative Identification
                                  Tentative  Structure
                 Temperature of
             Maximum Formation  (C)
                                                            In  N-
                                                                          In  Air
 Octachlorostyr
               ene
                                                              725
                                                                           ND
 Hexachlorodihydronaphthalene
-CI4
                                                              725
                                                                           630
  Unknown chlorinated compound
    Molecular Weight 400
                 725
                               ND
  aldentifications are based on mass spectra alone and are strictly tentative.
   Standards were not analyzed to confirm these identifications, and in some cases,
   library spectra were not available for comparison.

  bND=«not detected on TDAS, with a detection limit of about 2% conversion of parent
                                         41.

-------
TABLE 11. SUMMARY OF THERMAL DECOMPOSITION DATA
Compound
Acetonitrile
Tetrachloroethylene
Acrylonitrile
Methane
Hexachlorobenzene
1,2,3, 4-Tetr achlorobenzene
Pyridine
Dichlorome thane
Trichloroethylene
Carbon Tetrachloride
Hexachlorobutadiene
1 , 2 ,4-Trichlorobenzene
1 , 2-Dichlorobenzene
Ethane
Benzene
Aniline
Monochlorobenzene
Nitrobenzene
Hexachloroe thane
Chloroform
1,1, 1-Trichloroethane
Triallate
Trifluralin
Empirical
Formula
C2H3N
C2C14
C3H3N
CH4
CfrCIft
C6H2C14
C5H5N
CH2C12
C2HC13
CC14
C4C16
C6H3C13
C6H4C12
C2H6
^6^6
C6H7N
C6H5C1
C6H5N02
C2Clg
CHC13
C2H3C13
C10H16NSOC13
CnHifiNiiOAF*
onset ^}
(C)
760
660
650
660
650
660
620
650
600
600
620
640
630
500
630
620
540
570
470
410
390
360
360
T99 (2)
(C)
900
850
830
830
820
800
770
770
765
750
750
750
740
735
730
730
710
670
600
590
570
470
440
T99.99 (2)
(C)
950
920
860
870
880
850
840
780
935
820
780
790
780
785
760
750
780
700
640
620
600
525
477
                        42.

-------
TABLE 12. SUMMARY OF FIRST ORDER KINETIC RESULTS
Compound
Trichloroethylene
Aery lonit rile
Ace tonit rile
Tetrachloroethylene
Methane
Hexachlorobenzene
1,2,3, 4-Tetrachloro benzene
Ethane
Carbon Tetrachloride
Mono chloro benzene
Dichloromethane
1,2, 4-Trichlorobenzene
Pyridine
1, 2-Dichlorobenzene
Hexachlorobutadiene
Benzene
Aniline
Nitrobenzene
Hexachloroethane
Chloroform
1,1,1-Trichloroethane
Trial late
Trifluralin
ACs-1) E (kcal/mole
4.2xl03
1.3xl06
4.7xl07
2.6xl06
3.5xl09
2.5xl08
1.9xl06
1.3xl05
2.8xl05
8.0xl04
3. 0x10 13
2.2xl08
1-lxlO5
3.0xl08
6. 3x10 12
2. 8x10 8
9. 3x10 15
1.4xl015
1.9xl07
2. 9x10 12
1.9xl08
6.8xl08
2. 7x10 7
18
31
40
33
48
41
30
24
26
23
64
39
24
39
24
38
71
64
29
49
32
31
25
Temperature
) Range
600-700
750-810
800-850
725-825
700-800
710-785
700-765
675-725
680-730
600-670
700-755
675-725
700-750
685-725
700-750
685-715
650-700
600-650
500-600
520-585
475-550
360-460
360-430
Calculated
TQQ(2)(°C)
913
910
908
900
874
845
834
830
824
810
796
789
767
766
763
757
726
672
641
606
601
516
483
                       43.

-------
TABLE 13.  SUMMARY OF FRACTIONAL REACTION ORDER CALCULATIONS
Compound
Acetonitrile
Acrylonitrile
Aniline
Benzene
Carbon Tetrachloride
Chloroform
1, 2-Dichloro benzene
Dichlorome thane
Ethane
Hexachlorobenzene
Hexachlorobutadiene
Hexachloroethane
Methane
Monochlorobenzene
Nitrobenzene
Pyridine
1,2,3, 4-Tetrachlorobenzene
Tetrachloroethylene
Trial late
1,2, 4-Trichlorobenzene
1,1, 1-Trichloroethane
Trichloroethylene
Trifluralin
Temperature
(C)
850
810
700
720
730
585
725
752
725
785
730
600
800
670
650
750
740
825
460
725
550
700
430
Reaction
Order
a
1.1
1.6
1.1
1.1
1.5
1.1
1.3
0.9
1.0
0.9
1.0
1.2
1.2
1.6
1.1
1.3
1.3
1.1
1.4
1.4
1.2
1.3
1.3
r2
1.00
0.98
1.00
0.90
1.00
0.98
1.00
0.50
0.98
1.00
0.99
0.97
0.93
0.89
1.00
0.99
0.90
0.99
0.99
0.99
0.96
0.99
0.99
                            44.

-------
of fl i| ranks the compounds by their experimental Tgg (2) in an atmosphere
     owing air.  Table 12 presents the Ea and A values for the compounds
ranked by calculated T99 (2).  Table 13 summarizes the calculated fractional
      on orders for the compounds, which can be used to estimate the concen-
tration dependence of the destruction efficiency of the pure compounds.
Ihe theoretical formalism and experimental design for these studies is
available from other reports to which the reader is referred for additional
information (1).
                                     45.

-------
 REFERENCES

 1.   Dellinger, B., J.L. Torres, W.A. Rubey, D.L. Hall, J.L.  Graham and
      R.A. Games.  "Determination of the Thermal Stability of Selected
      Hazardous Organic Compounds."  Hazardous Waste,  Vol. 1,  No. 2, 1984.

 2.   Kramlich, J.C., et. al.  "Laboratory Scale Flame-Mode Hazardous Waste
      Thermal Destruction Research."  Revised Draft.  Final Report by EERC
      to the U.S. Environmental Protection Agency Prime Contract Number,
      68-03-3113 under Subcontract Task 24-1, 1983.

 3.   "The Mechanisms of Pyrolysis, Oxidation, and Burning of  Organic
      Materials." L.A. Wall, editor.  Proceedings of the 4th Materials
      Research Symposium held by NBS, Gaithersburg, MD.  NBS Special
      •Publication 357, CODENrXNBSAV, 1972.

 4.   Graham, J.L.,  D.L. Hall and B. Dellinger.  "Laboratory Investigation
      of the Thermal Degradation of a Mixture of Hazardous Organic Compounds
      - I." Accepted to Env. Sci. & Tech., June, 1985.

 5.   Clark, W.D., J.F. LaFond, O.K. Moyeda,  W.F. Richter and  W.R. Seeker.
      "Engineering Analysis of Hazardous Waste Incineration:  Failure Mode
      Analysis for Two Pilot-Scale Incinerators."  Presented at the llth
      Annual Hazardous Waste Research Symposium, Cincinnati, Ohio, April,
      1985.

 6.   Clark, W.D., M.P. Heap, W. Richter and  W.R. Seeker.  "The Prediction
      of Liquid Injection Hazardous Waste Incinerator  Performance."  Pre-
      sented at the ASME/AIChE 22nd National  Heat Transfer Conference.

 7.   Vandell, R.D.  and L.A. Shadoff.  Chemosphere, Vol. 13, No. 11, 1984.

 8.   Benson, S.W.  Thermochemical Kinetics,  (John Wiley & Sons, New York,
      1976).

 9.   Jackimowski, C.J.  Combustion & Flame,  55, 213-224, 1984.

10.   Grumpier, E.P-, E.J. Martin and G. Vogel.  "Best Engineering Judgment
      for Permitting Hazardous Waste Incinerators." Presented at ASME/EPA
      Hazardous Waste Incineration Conference, Williamsburg, Virginia, May,
      1981.

11.   Cudahy, J.J. and W.L. Troxler.  "Autoignition Temperature as an
      Indicator of Thermal Oxidation Stability."  Journal of Hazardous
      Materials, 8,  1983.

12.   Tsang, W. and W. Shaub.  "Chemical Processes in  the Incineration of
      Hazardous Materials."  Detoxification of Hazardous Waste, Chapter 2.
      Exner, J.H., editor (Ann Arbor Science  Publishers, Ann Arbor, MI
      pp. 41-60, 1982).

13.   Miller, D.L.,  V.A. Cundy and R.A. Matula.  "Incinerability Character-

                                     46.

-------
      istics of Selected Chlorinated Hydrocarbons."   Proceedings  of  the  9th
      Annual Research Symposium on Solid and Hazardous  Waste  Disposal,
      Cincinnati, Ohio, May, 1983.

14.   Lee, K.C., N. Morgan, J.L. Hansen and G.M.  Whipple.   "Revised  Model
      for the Prediction of the Time-Temperature  Requirements for Thermal
      Destruction of Dilute Organic Vapors and Its Usage  for  Predicting
      Compound Destructibility."  Presented at the 75th Annual Meeting of
      the Air Pollution Control Association, New  Orleans,  LA., June,  1982.

15.   "Performance Evaluation of Full-Scale Hazardous Waste Incinerators."
      Final Report.  MRI Report submitted to the  U.S. Environmental  Pro-
      tection Agency, Contract 68-02-3177, August, 1984.

16.   Dickson, W.J. and F.J. Massy, Jr.  Introduction to  Statistical
      Analysis, 2nd ed., McGraw-Hill, New York, 1957-

17.   Bellinger, B., D.L. Hall, J.L. Graham and W.A.  Rubey.  "Destruction
      Efficiency Testing of Selected Compounds and Wastes."  Final Report to
      Eastman Kodak Company, September, 1984.

18.   Wolbach, C.D. and A.R. Gorman.  "Destruction of Hazardous  Wastes  Co-
      fired in Industrial Boilers:  Pilot-scale Parameters Testing."
      Acurex Draft Final Report FR-84-46-EE, February,  1984.

19.   Wyss, A.W., C. Castaldini and M.M. Murray.   "Field Evaluation  of
      Resource Recovery of Hazardous Wastes."  Acurex Technical  Report  TR-84-
      160/EE, August, 1984.

20.   "Evaluation of Waste Combustion in Cement Kilns at General Paulding,
      Inc., Paulding, Ohio."  Draft Final Report  to U.S. Environmental
      Protection Agency, prepared by Research Triangle Institute and
      Engineering Science, March, 1984.

21.   Trial Burn Report for Kodak Park Division Chemical Waste Incinerator.
      U.S. Environmental Protection Agency, ID.   No. NYD980592497-

22.   Bastian, Ron.  Private Communication.

23.   Cooke  M., R.E. Hall and W.H. Axtman.   "PNA Emissions  in Industrial
      Coal-Fired Stoker Boilers."  Presented  at the 185th  National ACS
      Meeting in Seattle, Washington, March,  1983.

24.   Hall  D.L., B. Dellinger and W.A. Rubey.  "Considerations  for the
      Thermal Degradation of Hazardous Waste."  Presented  at  the 4th Inter-
      national Symposium on Environmental Pollution, Miami Beach, FL,
      October, 1983.

25    Shilov  A.E. and R.D. Sabirova.  Russian Journal of  Physical Chemistry,
      34:408, I960.

26.   Choudhry, Ghulam G., 0. Hutzinger.  Mechanistic Aspects of  the Thermal

                                     47.

-------
      Formation of Halogenated Organic Compounds Including Polychlorinated
      Dibenzo-p-Dioxins, Gordon and Breach Science Publishers. New York,
      1983.

27.   Benson, S.W. and H.E.  O'Neal.  "Kinetics Data on Gas-Phase Unimolecular
      Reaction."  NSRDS Report, NBS-21,  U.S. Government Printing Office, 1970.

28.   Tully,  F.P-   Chem. Phys.  Letters,  96,  No. 3, 1983.

29.   Tulley, F.P., et. al.   J. Phys.  Chem., 85, 1981.

30.   Staley, L.J.  "CO and  DRE:   How Well Do They Correlate?"  Presented at
      the U.S. Environmental Protection  Agency's llth Annual Research Sym-
      posium, Cincinnati, Ohio, April,  1985.

31.   Mournighan,  R.E.   "Surrogate Chemical  Tracers for Incineration."
      Presented at the  U.S.  Environmental  Protection Agency's llth Annual
      Research Symposium, Cincinnati,  Ohio,  April, 1985.

32.   Wolbach, C.D. and A.R.  Gorman.   "Destruction of Hazardous Wastes Co-
      fired in Industrial Boilers:   Pilot-Scale Parametrics Testing."  Acurex
      Draft Final  Report FR-84-46/EE,  February, 1984.

33.   Waterland, L.R.   "Pilot-scale Investigation of Surrogate Means  of
      Determining  POHC  Destruction."  Acurex Final Report  FR-83-135/EE,
      July, 1983.
                                    48.

-------