EPA-600/2-76-299
December 1976
Environmental Protection Technology Series
LABORATORY EVALUATION OF HIGH-TEMPERATURE
DESTRUCTION OF KEPONE AND
RELATED PESTICIDES
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/2-76-299
December 1976
LABORATORY EVALUATION OF HIGH-TEMPERATURE
DESTRUCTION OF KEPONE AND RELATED PESTICIDES
by
D. S. Duvall
W. A. Rubey
University of Dayton Research Institute
Dayton, Ohio 45469
Grant No. R-803540-01-0
Project Officer
Richard A. Carnes
Solid and Hazardous Waste Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTIONAL AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U. S. Environmental Protection Agency, nor
does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
11
-------
FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching
for solutions. The Municipal Environmental Research Laboratory develops
new and improved technology and systems for the prevention, treatment, and
management of wastewater and solid and hazardous waste pollutant discharges
from municipal and community sources, for the preservation and treatment
of public drinking water supplies, and to minimize the adverse economic,
social, health, and aesthetic effects of pollution. This publication is one
of the products of that research; a most vital communications link between
the researcher and the user community.
Surplus, unwanted, and highly hazardous pesticides pose safety hazards to
the public and are potential sources of environmental contamination. The
study reported herein presents thermal decomposition data for several
pesticides based on a specially designed laboratory technique.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
ill
-------
DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protecbion Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U. S. Environmental Protection Agency, nor
does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
11
-------
FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching
for solutions. The Municipal Environmental Research Laboratory develops
new and improved technology and systems for the prevention, treatment, and
management of wastewater and solid and hazardous waste pollutant discharges
from municipal and community sources, for the preservation and treatment
of public drinking water supplies, and to minimize the adverse economic,
social, health, and aesthetic effects of pollution. This publication is one
of the products of that research; a most vital communications link between
the researcher and the user community.
Surplus, unwanted, and highly hazardous pesticides pose safety hazards to
the public and are potential sources of environmental contamination. The
study reported herein presents thermal decomposition data for several
pesticides based on a specially designed laboratory technique.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
111
-------
PREFACE
The serious environmental contamination of the manufacturing facility,
sewage treatment works, and nearby environs by the pesticide Kepone
required attention to proper disposal techniques. After all disposal alter-
natives had been considered, the need to develop supporting data for the
chosen technology became evident. As discussions progressed, it became
more apparent that high-temperature controlled incineration offered a good
potential for successful disposal. Thermal degradation data for Kepone
were not available, however, and would have to be generated.
During this period researchers at the University of Dayton Research Institute
were developing a thermal oxidation apparatus for determining the thermal
behavior for a wide variety of pesticides. Responding to an urgent request
from the Special Kepone Task Force, the researchers embarked on a high-
intensity, short-turnaround project on Kepone. Within 3 months, by early
Spring of 1976, substantial data were developed and a special technical
report submitted to the EPA Project Officer for distribution to involved
parties. This report has subsequently formed the data base in support of
planned pilot plant burns of Kepone and Kepone-contaminated sludge.
IV
-------
ABSTRACT
The serious problems concerning Kepone manufacturing operations in
the Hopewell, Virginia, area have been widely publicized. Disposal problems
and environmental cleanup associated with Kepone found in soil, water,
sewage sludge, etc. have been substantial. Thermal disposal was considered
to be a primary means for solving this disposal problem. However, basic
high-temperature data on Kepone were lacking; accordingly, this study was
aimed at providing necessary information.
Thermal destruction testing was conducted with three pesticides: Kepone,
Mirex, and DDT. A specialized laboratory technique incorporating a two-
stage quartz system was developed. It is important to note that in this system
the pesticide was first converted to the gas phase, then exposed to the high-
temperature destruction conditions. Critical parameters of temperature and
residence time were accurately measured. Both the Kepone and DDT mole-
cules, at a residence time of ~1 second, were essentially destroyed at
500° C; however, Mirex, at the same residence time, required 700° C for
destruction.
This report was submitted in partial fulfillment of Grant No. R-803540-01-0
by the University of Dayton Research Institute under the sponsorship of
the United States Environmental Protection Agency.
-------
CONTENTS
Page
Foreword i-ii
Preface iv
Abstract v
Figures viii
Acknowledgments ix
I. Introduction 1
II. Conclusions 3
III. Significance of Laboratory Investigation 5
IV. Laboratory Approach 6
V. Experimental 10
VI. Results and Discussion 29
Appendix
I. Error Analysis of Mean Residence Time Determination ... 49
II. Pesticide Residence Time Distribution 52
References 57
vii
-------
FIGURES
Number Pa§e
1 Chemical Structures 2
2 Residence Time of Gas Phase Molecules 8
3 TG Analysis of Kepone 12
4 TG Analysis of Mirex 13
5 TG Analysis of DDT 14
6 Schematic of Quartz Tube Apparatus 16
7 Sample Holder 17
8 Effluent Trap 18
9 Sketch of Pressure, Volume, and Temperature
Relationship in Test System 20
10 Temperature Profile of Quartz Tube Furnace 23
11 Electrical Schematic of Pressure Transducer 24
12 Interior of Modified Tracer 550 27
13 Programmed Temperature GC Analysis Conditions 30
14 Chromatogram of Thermally Stressed Kepone 31
15 Chromatogram of Thermally Stressed Mirex 32
16 Chromatogram of Thermally Stressed DDT 33
17 Series of Chromatograms from Thermally Stressed
Kepone 34
18 Thermal Destruction Plot for Kepone 36
19 Thermal Destruction Plot for Mirex 37
20 Thermal Destruction Plot for DDT 38
21 Comparison of Thermal Destruction of the Three
Pesticides 39
22 DTA Tracings of the Three Pesticides 42
23 Chromatograms Showing Kepone Levels 44
24 Effect of Residence Time on Thermal Destruction of
Kepone 45
25 Residence Time Distribution Data 55
viii
-------
ACKNOWLEDGMENTS
The authors wish to acknowledge the assistance of R.A. Games, the EPA
project officer. Also> they wish to express their appreciation to R.A. Grant
for his help in the glassware design and fabrication, to B. H. Wilt and
M. Craycraft for the DTA testing, to J. M. Hotz for the TG testing, and to
R. G. Keil andB.L. Fox for their critical review of the report.
ix
-------
SECTION I
INTRODUCTION
The problems associated with the safe disposal of unwanted or hazardous
pesticides has been recognized for several years. Recently, the pesticide
Kepone has received national attention for various reasons [1, 2]. Suffice
it to say that Kepone is a chlorinated carbon with a carbonyl group; that it is
toxic and probably bioaccumulative; it is suspected of being a carcinogen;
and that it closely resembles the pesticide Mirex that has been shown to be
thermally stable [3].
Prior to the initiation of this study, there existed no reported thermal de-
composition data for Kepone. This report is primarily concerned with the
high temperature destruction of Kepone, with DDT and Mirex being used as
comparative analogues. 'DDT has been the most studied compound as far as
thermal decomposition is concerned, while Mirex is thermally stable and very
close in molecular structure to Kepone. The exact chemical structures are
shown in Figure 1.
This study was designed to provide data from which requirements can be
^assigned for the thermal disposal of Kepone. Accordingly, the specific
•"objective of the laboratory effort was to establish destruction temperature
characteristics of the vaporized pesticides at preselected residence times.
A major part of this program involved examinations of the gas phase destruc-
tion behavior of the selected pesticides for completeness of destruction and
identification of decomposition products while in a controlled-flow, high-
temperature air environment. The work was performed utilizing special
instrumentation designed by University of Dayton Research Institute
(UDRI) personnel. The pesticides selected for study were also evaluated
by standard thermoanalytical techniques of thermogravimetry (TG) and
differential thermal analysis (DTA).
-------
c/
KEPONE
C/
c/ c/
MIREX
CX
C/'
c/
p.p-DDT C/
Figure 1. Chemical Structures.
2
-------
SECTION II
CONCLUSIONS
1. A laboratory technique was developed for determining the thermal
destruction characteristics of pesticides. Results for Kepone,
Mirex, and DDT showed that the parent molecule for each was
essentially destroyed at a one second residence time and a temperature
range of 500°C-700°C, depending on the pesticide.
2. Kepone was found to be slightly more thermally stable than DDT.
Therefore, based on the conclusions of others that established a two
second residence time and 1, 000° C temperature requirement for safe
incineration of DDT, the results of this research show that any in-
cineration of Kepone should, at least, meet the aforementioned re-
quirements for DDT.
3. Analyses showed major decomposition products to be hexachloro-
cyclopentadiene and hexachlorobenzene (HCB) for both Kepone and
Mirex. These products were formed in different thermal regions;
and trace (but detectable) levels of HCB were still present at 900°C.
4. Residence time was found to be important in the thermal decomposition
of Kepone at a temperature predetermined to be a reactive region.
5. Differential Thermal Analysis (DTA) showed no thermal reaction
areas (exotherms or endotherms) above 600°C. These findings are
contradictory to results reported by others.
6. This laboratory-scale technique can be used to develop quick response
thermal stability baseline data for organic materials posing environ-
mental disposal hazards, and for which no previous thermal data
exist.
-------
7. This study clearly demonstrated that the chemical nature of the
effluent products is dependent on the temperature and residence time
that the basic molecule experiences. Thus, precise analytical data
which identify and quantify decomposition and/or recombination pro-
ducts, with respect to these two parameters, are necessary for estab-
lishing guidelines for safe thermal disposal of hazardous materials.
4
-------
SECTION III
SIGNIFICANCE OF LABORATORY INVESTIGATION
The objective of the study discussed in this report was to obtain laboratory
test data that could be applied to a large-scale system for the thermal dis-
posal of Kepone and similar pesticides. The rabher unique approach utilized in
this study permitted the gathering of basic thermal destruction data under
controlled residence times.
In this study, the laboratory data were obtained by subjecting pure pesticides
to a two-step destruction process. First, the pesticide was vaporized at a
low temperature, 200°C to 300°C; then the gas phase sample was passed
through a high-temperature quartz tube. The distinct advantage of this labo-
ratory approach is that thermal destruction data can be obtained while both
temperature and residence time are being controlled and accurately mea-
sured. This contrasts sharply with large-scale conditions where the pesticide
would be introduced as a solid or liquid, and often as a mixture containing
foreign materials such as organic solvents or inorganic solid supports. In
this situation, attainment of a given temperature is hindered by the fact that
the necessary phase changes of the pesticide must occur even while the in-
sulating and possible retentive effects of inorganic sorbents are being over-
come. Under such conditions, the measured reaction chamber temperature
will not reflect the true temperature that the pesticide molecule actually
experiences. Also, accuracy of residence time measured in the large-scale
system suffers from the shortcomings graphically displayed and discussed in
Section IV.
This laboratory study clearly showed that the complicated chemical nature
of pesticide thermal destruction products is strongly dependent on the
temperature and residence time that the pesticide encounters. Therefore, it
is most important to acquire precise analytical data which identify and quantify
decomposition products relative to exposure temperature and residence time.
The above laboratory approach is ideally suited for obtaining these basic
data which are needed to insure logical decision making in the thermal dis-
posal of pesticides.
5
-------
SECTION IV
LABORATORY APPROACH
In order to determine the high-temperature destruction characteristics of an
organic molecule, it is necessary to obtain precise information on certain
crucial parameters. It is important that the system temperature be accurately
determined, along with the residence time, i.e., the time interval during
which the molecule experiences the destructive temperature. Another critical
parameter that must be fulfilled in such an evaluation is that there be an
adequate supply of air so that the destruction takes place in an oxidative
environment, as opposed to an atmosphere containing insufficient oxygen.
Lastly, an important factor is the composition of the high-temperature
environment, e.g., water content, presence of other gases, and interfering
materials such as clays, fillers, organic sorbents, etc.
The laboratory approach to establishing a pesticide's high-temperature, non-
flame destruction characteristics has certain distinct advantages. First, if
one examines the pure pesticide, no interferences are encountered from
other materials. Second, the composition of the high-temperature environ-
ment can be precisely established by using compressed air of known quality
and employing in-line filters to remove water, oil, and other foreign materials.
Next, by using a technique whereby a small sample of pesticide is gradually
vaporized; and, then passed through a high-temperature zone, one is assured
of an excess of oxygen, thus avoiding the possibility of a pyrolytic reaction
occurring. Further, it is possible to evaluate the behavior of the pure
pesticide on the molecular level. By vaporizing the pesticide prior to its
exposure to the high-temperature environment, one can be assured, based on
the kinetic theory of gases [4], that pesticide molecules do indeed experience
the actual average temperature. Finally, the laboratory evaluation of a
pesticide's destruction characteristics can be accomplished quickly and
economically with minimum environmental risk.
-------
It is important to note that during incineration of a pesticide formulation, a
certain amount of energy must be applied just to change the incorporated
pesticide from its usual state (whether it be solid or liquid) to the gas phase.
These phase transitions, apart from requiring additional energy, also re-
quire an undefined amount of exposure time to the high-temperature source.
Therefore, it is almost certain that in the case of the incineration of pesticide
formulations, some pesticide molecules do not encounter the prescribed
incineration temperature. In short, even through the temperature within a
chamber is known, it does not necessarily mean that all substances within
that chamber have indeed attained thermal equilibrium. However, if all of
the substances in the chamber are in the gas phase, one can safely assume
that the individual molecules have (with sufficient time exposure) achieved
the average temperature of that environment.
For similar reasons, the laboratory evaluation of a pesticide's residence
time is considerably simplified over that of measuring residence time in a
large scale unit. When a gas is passed through a lengthy narrow-bore flow
path (in the laminar flow region), radial dispersion can be neglected and the
main factor affecting the residence time distribution is longitudinal diffusion.
However, for large diameter, mixing chamber, or multichamber flow paths,
radial dispersion is the major factor effecting the variation in residence time
of the transported molecule [5]. Figure 2 depicts the residence time dis-
tributions for pesticides passing through the two different flow paths. The
exact contour of these generalized profiles would be dependent upon the
nature of the flow, i.e. , laminar or turbulent, and other factors such as wall
composition [6] and surface finish. However, in general, residence time
can be accurately measured with a narrow-bore flow path, whereas for the
large diameter flow path, molecular residence time can, at best, only be
approximated. This situation can be illustrated by observing in Figure 2a
that some pesticide molecules can pass through the large diameter flow path
-------
(a)
CONCENTRATION
RESIDENCE TIME
(b)
CONCENTRATION
RESIDENCE TIME
Figure 2. Residence Time of Gas Phase Molecules.
(a) Large Diameter, Mixing Chamber, or Multichamber
Flow Path.
(b) Narrow-Bore Flow Path.
-------
in a very short time; while some mole'cules, as evidenced by the asymptotic
behavior of the right-hand side of the same curve, can remain in the high-
temperature region for an extended period of time.
Two approaches were considered for obtaining high-temperature destruction
data on the pesticides: (1) a discontinuous system where the thermal stressing
of the pesticide, and product analysis are separate, and (2) a closed, con-
tinuous system incorporating both thermal stressing and product analysis.
In the discontinuous system, the effluent sample is trapped, then removed
from the thermal processor and inserted into the gas chromatograph for
analysis. In a closed, continuous system, the thermal processor would be
connected to the gas chromatograph. A decision was made to go with the dis-
continuous system, as it would be simpler to develop, and a logical first
approach for acquiring the desired data.
Proceeding with this approach, Kepone, Mirex, and DDT were evaluated in
a series of tests where the pesticide was first vaporized and then trans-
ported through a narrow-bore, high-temperature zone by a controlled flow
of air. In this way, average temperature and residence time were firmly
established. These tests were conducted at a series of temperatures
ranging approximately from 250 C to 900 C. Also, the effluent from each
high-temperature test was passed through a trapping medium and the
collected fraction was subsequently analyzed by gas chromatography. In
addition to the foregoing investigation, standard examinations by TG and
DTA were utilized to acquire basic thermal data on each pesticide.
-------
SECTION V
EXPERIMENTAL
Description of Samples
This study was concerned primarily with the behavior of the pure pesticide;
therefore, only samples of known purity were used. Kepone, Mirex, and
DDT reference standards were obtained from the National Environmental
Research Center, Research Triangle Park, North Carolina. The pesticide
reference standards were examined in a series of high-temperature destruc-
tion tests and were also subjected to thermogravimetric analysis (TG).
Mirex and DDT samples obtained from Applied Science Laboratories, State
College, Pennsylvania were investigated by differential thermal analysis
(DTA). The sample used for the DTA of Kepone was obtained by
recrystallizing an 80 percent Kepone formulation supplied by the project
officer. As these pesticides are solids at room temperature, it was
necessary to dissolve them with a volatile solvent. Subsequently, a mixture
of acetone and benzene (50:50 by volume) was selected for dissolving the
three pesticides.
Before conducting any tests, the reference standard pesticides from
Research Triangle Park were examined by gas chromatography using both
a nonpolar column (OV-1) and a moderately polar column (1.5% OV-17 +
1. 95% QF-1). These samples were also analyzed by two different detection
methods; namely, hydrogen flame ionization detection (HFID) and electron
capture detection (ECD).
As the DDT sample was a mixture of isomers, numerous peaks were
observed, although the sample did appear to contain approximately 80%
p,p'-DDT and 20% o,p'-DDT. The Mirex reference standard was found to
be very pure and in all cases yielded a single chromatographic peak. The
10
-------
Kepone sample showed only a single peak when examined by HFID, however,
when examined by ECD, trace levels were observed of substances consi-
derably heavier than Kepone.
Thermal Analysis
Before conducting the high-temperature destruction tests, it was considered
desirable to obtain some basic thermal analysis data on the three pesticides.
Accordingly, each pesticide was subjected to a thermogravimetric analysis.
These TG analyses were conducted with a Fisher Series 100 thermogravi-
metric instrument. Small quantities of pesticide (approximately 2mg) were
tested while a flow of 60 ml/min of dried air was passed through the sample
region. Each sample was programmed from room temperature to approxi-
mately 900°C at the rate of 10°C per minute. The TG tracings for the
reference standard pesticides are shown in Figures 3, 4, and 5.
It was found from duplicate tests that TG repeatability was good; and, also,
that there was no visible residue in the platinum sample container upon com-
pletion of any of the tests. The TG tracings for Mirex and DDT showed
essentially an increasing rate of evolving material which suggests a simple
evaporation of the pesticide. The TG tracing for Kepone shows an early
weight loss between 30 and 50 C. Upon investigating this further, it seems
apparent that the submitted Kepone sample contained Kepone hydrate. Thus,
this early weight loss represents the evolution of water.
For the three pesticides, the indicated temperatures corresponding to the
completion of evaporation are aligned in the same order as the molecular
weights of the pesticides. That is, DDT is thermally removed first, followed
by Kepone and then Mirex.
11
-------
SAMPLE 2.05mg of KEPONE (REFERENCE STANDARD)
95°C
TF=995°C
/
/
/
WEIGHT
TEMPERATURE
START OF
TEMPERATURE PROGRAM
i i
I 100
1000
900
8OO
700 o
o
GOO £
500
400
300
200
100
0
30
60
90
TIME, MIN
120
150
180
Figure 3. TG Analysis of Kepone.
12
-------
100
* 80
z
1 60
5
UJ
^ 40
1-
X
CD
^ 20
0
SAMPLE 2. lOmg of MIREX ( REFERENCE STANDARD)
TF = 985°C
T\
. ,o, ^
-
_
/
S
T0=24°C ^
r-\*f'
^~ START OF
/
/
/
/
/
/
Uil
iif r-jpi IT
Wtion 1
TT (Ifl D IT D A T 1 IDr" —
1 tmrtKAl UKt
TEMPERATURE PROGRAM
i i i i i
1100
IOOO
900
800
700
o
o
600 £*
•
500 <
UJ
Q.
400 g
l-
300
200
100
0
30
60
90
TIME, WIN
120
150
180
Figure 4. TG Analysis of Mirex.
13
-------
SAMPLE- 2.10 mg of DDT ( REFERENCE STANDARD) ,,„„
100
8? SO
o
z
5 60
5
s
UJ
K 40
1-
i
o
^ 20
-
TF=860?C
X
10°°C \
\
I /
1 /
1 /
\ /
\ /
1 y
1 /
\ /
\ /
1 /
\ '
\ s
\
•'' £—\70"C
T« = 24°C ^- ^ \A/nniT
Pv^_ TEMPERATURE
TEMPERATURE PROGRAM
t 1 I i i
1 1 W
1000
900
8OO
700
o
o ^
6OO )jf
o
500 <
i£
UJ
Q.
400 S
ui
I-
300
200
100
0
3O
60
90
TIME, WIN
(20
150
180
Figure 5. TG Analysis of DDT.
14
-------
Samples of Kepone, Mirex, and DDT were also subjected to differential
thermal analysis. These tests were conducted with a DuPont 900 DTA
apparatus which utilized a purging air atmosphere. The DTA results will
be presented and discussed in Section VI.
Quartz Tube Apparatus
Figure 6 is a schematic of the high-temperature quartz tube apparatus
that was designed and assembled for the examination of pesticides. An
important component in this apparatus is the folded quartz tube which is
contained in a Lindberg furnace, type 55035A.
Two quartz tubes of different bore size were fabricated for this work. Both
tubes had an effective length, when positioned in the furnace, of 84 cm. By
using a mercury plug displacement method [7], the average inside diameters
of the finished, folded tubes were found to be 0. 80 mm and 2. 14 mm,
respectively.
Upstream of this folded quartz tube is a special sample holder which is
shown in Figure 7. With the use of a 10 microliter syringe and following
suggested procedure [8], a known quantity of pesticide can be readily
deposited on the sand blasted region of the sample holder. The solvent
quickly evaporates, leaving the pure pesticide on the rough Pyrex surface.
This device is then inserted into a chamber upstream of the high-temperature
quartz tube. Next, this chamber is heated to the extent necessary to
vaporize the pesticide; whereupon, the gas phase pesticide is swept through
the high-temperature tube.
An effluent trap is located at the outlet of the high-temperature tube. A
sketch of the basic trap is shown in Figure 8. This lengthy Pyrex tube
(22. 5 cm) is connected to the quartz tube outlet with a special Swagelok
15
-------
CZD
HIGH TEMPERATURE REGION
VENT
A. COMPRESSED AIR, BREATHING QUALITY GRADE
B. TWO STAGE PRESSURE REGULATOR
C. "HYDROPURGE" FILTER
D. FLOW CONTROL VALVE
E. PRESSURE TRANSDUCER
F SAMPLE HOLDER, PYREX
G. HEATED INLET CHAMBER
H QUARTZ TUBE
1. HEATED OUTLET CHAMBER
J EFFLUENT TRAP, TENAX-GC OR CHARCOAL
K. FLOW METER
Figure 6. Schematic of Quartz Tube Apparatus.
16
-------
SAMPLE DEPOSIT REGION
2.0cm BY 0.4cm DIAMETER
(SAND BLASTED)
GAS-TIGHT SEAL
3-SILICONE 0-RINGS)
HANDLE
PYREX ROD
25cm BY 0.6cm
\
ADJUSTABLE
SET- SCREW
RETAINER
Figure 7. Sample Holder.
17
-------
GAS FLOW
DIRECTION
SILANE
TREATED
GLASS
WOOL-y
PYREX TUBE
TRAPPING MEDIUM
SILANE 3.0mm-
TREATED
GLASS 1.8mm-
WOOL
—J0.80
:m
•— 2.0cm—•|o.8cm[«—
1.5cm
22.5cm
rr
Figure 8. Effluent Trap.
18
-------
reducer union containing a Teflon sleeve. A gas tight seal is obtained with
the use of Vespel ferrules. The outlet of the trapping medium tube
approaches ambient temperature.
During this study, different trapping media were employed. Tenax-GC was
found to be an excellent trapping medium for the three pesticides and their
larger fragmentation products. Tenax-GC, a porous polymer, is currently
commercially available in 35/60 and 60/80 mesh sizes. Also, this material
has a desirable feature in that it can be readily, thermally desorbed [9-16].
Traps prepared with the 60/80 mesh Tenax-GC particles performed quite
well and did not present an excessive pressure drop. Also, a 2. 0 cm length
of Tenax-GC was sufficient to obtain quantitative recoveries of the pesti-
cides. However, acetone and benzene were not quantitatively retained at the
typical trap inlet temperature of approximately 300 C. Charcoal [17, 18]
was also used as a trapping medium in this study, and was found to be an
excellent trapping material for these three pesticides.
Other important components in this high-temperature destructive apparatus
are a Porter flow control valve (model number VCD-1000), a differential
pressure transducer, two Blue M model APH-500 temperature indicators
which continually display the temperatures of the inlet and outlet chambers,
and a specially fabricated soap-bubble flowmeter for measuring the system's
outlet flow rate. The gas used in this study was breathing-quality com-
pressed air which was passed through an Applied Science Laboratories
Hydro-Purge filter. The average temperature in the high-temperature fur-
nace was continually monitored by the digital readout from a compensated
chromel-alumel thermocouple.
From the sketch shown in Figure 9, it is seen that the pressures, tempera-
tures, and volumes in this system can be related according to the ideal gas
law as,
19
-------
GAS FLOW
=
INLET
EFFLUENT
TRAP
V2 . P2
P|
OUTLET
Figure 9. Sketch of Pressure, Volume, and Temperature Relationship
in Test System.
20
-------
V,P, V p
-~^=-~^, (v.i)
T2 °
where V is volume, p is pressure, and T is temperature. The subscript ^
denotes the quartz tube interior, while the subscript £ represents the
ambient outlet conditions.
Due to the extremely low pressure drop posed by the open quartz tube, and
the comparatively high pressure,drop presented by the packed small particle
effluent trap, the differential pressure p, can be expressed as
PJ = Po'P^ = Pi'P,, • (v- 2>
d c. o 1 o
Now, volume flow F can be written as
F = -£-, (V. 3)
where t is time, equation (V. 1) can be rewritten as
V_p_ F tp
22 o *
or
T2
irr Lp, F tp
2 o o
T , (V. 4)
r. 5)
where r and L are the tube radius and length, respectively. Therefore, it
is seen that time, or in this case residence time, can be written simply as
21
-------
(V. 6)
where t represents the calculated mean residence time of a substance in
the quartz tube interior.
Special measurement equipment is required to measure the outlet flow, the
temperature of the quartz; tube, and the upstream differential pressure.
Specifically, the outlet flow is measured with a small bore soap-bubble
flowmeter having an in-line water saturator [19]. This device was fabri-
cated in the University Glass Shop and incorporated a calibrated volumetric
pipette in the design. The average temperature of the quartz tube was
determined by measuring the axial temperature profile in the Lindberg fur-
nace and then determining the location of a point within the furnace which
would represent the average temperature. This point was found to be at a
location 9 cm from the axial midpoint of the furnace. The temperature pro-
file for the contained, folded quartz tube is shown in Figure 10. This ther-
mal information was obtained with a chromel-alumel thermocouple which was
used to measure the temperature at 1 cm increments along the tube furnace
axis. The average temperature that a pesticide will encounter during its
gas phase traverse through the quartz tube will be represented by 1 as
shown in Figure 10.
The pressure within the quartz tube is difficult to measure. A low pressure
gage, such as a Bourdon gage, customarily exhibits high degrees of
inaccuracy, along with a large mechanically induced hysteresis. Conse-
quently, a very precise pressure transducer was utilized for measuring the
differential pressure at the inlet to the quartz tube. This pressure trans-
ducer (see Figure 11) was found to be extremely accurate, linear, and
22
-------
1200
1000
800-
-------
CONTROLLED
POWER
SUPPLY
(15.0 VDC)
STATHAM STRAIN GAGE
DIFFERENTIAL PRESSURE
TRANSDUCER
DIGITAL
•VOLTMETER
• (mv)
Figure 11. Electrical Schematic of Pressure Transducer.
24
-------
exhibited no hysteresis. The output from the pressure transducer was
displayed on a digital millivoltmeter. Throughout this study it was observed
that the differential pressure varied with the particle size of the trapping
medium and the linear gas velocity.
The determination of mean residence time was subjected to an error analysis
which is described in Appendix I. Essentially, as a result of this error
analysis, it was found that mean residence time can be accurately determined
provided F , T , and p are also measured with accuracy.
Even though the mean residence time can be accurately determined, addi-
tional information is needed concerning the distribution of the residence
times of different molecules. The residence time distribution of the pesti-
cide molecules can be studied in the same manner as if they entered the
quartz tube as a concentrated narrow pulse (Appendix II). Also, the behavior
of different molecular weight substances at different temperatures has been
investigated. It was found that different molecular weights (different pesti-
cides) produced only a very small effect on the respective residence time
distribution; however, the residence time distribution was found to be
strongly dependent upon temperature, as described in Appendix II. Even
so, a fairly small tolerance can be applied to the mean residence time and
still envelope the rapidly migrating molecules.
Once the pesticide molecules, or fragments and products thereof, have
passed through the high-temperature quartz tube, they are trapped in, or on,
the sorbing medium of the effluent trap. This trap is then removed from the
high-temperature apparatus. A quantitative standard is then deposited in
the trap (4. 0 ug of _n - octadecane in a 50:50 vol mixture of acetone and
benzene). The contents are then subjected a programmed temperature gas
chromatographic analysis using a modified Tracer 550 Instrument.
25
-------
The injector of this gas chromatograph has been modified so that it will
accept the Pyrex tube containing the trapping medium and its sorbed sample.
Modifications to the chromatograph have been made so that thermal desorp-
tion of the trapping medium can be conducted while it is positioned just
upstream of the column packing (see Figure 12). This is accomplished with
the use of a cartridge heater embedded in an aluminum block which surrounds
the inlet region of the glass column. By heating this inlet region to 260 C
for 10 minutes, complete desorption of the trapped effluent is accomplished.
This desorption is made with the chromatographic oven at room temperature;
therefore, the products are swept from the trapping medium and deposited
on the inlet portion of the packed column.
After a suitable thermal desorption time (10 minutes), the chromatographic
oven is closed and the temperature is programmed to 260 C at the rate of
14 C per minute. It has been found that the 1. 8 meter length OV-1 column
efficiently elutes Kepone, Mirex, DDT, and their various decomposition
products when this GC procedure is used. (With this trapping and thermal
desorbing technique, essentially quantitative transfer of the three pesticides
was achieved. )
Charcoal can be substituted for the Tenax-GC in the effluent trap; however,
the trap must then be chemically desorbed, rather than thermally.
Accordingly, after selecting suitable solvents, the charcoal trap was chemi-
cally desorbed and the contents analyzed with a gas chromatograph using
either HFID or ECD. This form of effluent trapping and chemical desorption
was performed for the three pesticides at the highest temperature studied,
namely 900 C.
The effect of residence time on the high-temperature degradation was also
of interest. With the high-temperature quartz-tube apparatus, Kepone was
examined at a region of high thermal degradation, namely in the vicinity of
26
-------
INSULATION
EXTERNAL POWER
SUPPLY AND
TEMPERATURE
CONTROL
*n
*U
INJECTOR
CAP
^^^^^^maafa^fm
I
HELIUM
CARRIE
OVEN DOOR
II TBAQBIKIf*
II TRAPPING
MEDIUM
==^^*Iv^Ov4AV/V: -T
ALUMINUM BLOCK
WITH EMBEDDED
CARTRIDGE HEATER
R
vVYVY\Y
I HFID -
^INSULATION
*• VENT
GLC COLUMN
X(PYREX)
I.8M, OV-I
Figure 12. Interior of Modified Tracor 550.
27
-------
420 to 440 C. At temperatures less than this, Kepone was passed through
the quartz tube essentially intact. At higher temperatures, Kepone was
observed to decompose rapidly. Accordingly, samples of Kepone were
subjected to three successive tests at a constant T of 433 C, but with
L*
different residence times. The trapped effluents from these three tests
were then analyzed. The effect of Kepone residence time at 433 C was i
evaluated from the effluent data.
28
-------
SECTION VI
RESULTS AND DISCUSSION
High-Temperature Vapor Phase Destruction
Samples of each pesticide were subjected to a series of high-temperature
destruction tests. The trapped effluent from each test was then analyzed
by GC as described by the conditions listed in Figure 13. Typical chroma-
tograms corresponding to thermally stressed Kepone, Mirex, and DDT are
shown in Figures 14, 15, and 16, respectively. The entire series of
chromatograms corresponding to the examination of Kepone is presented in
Figure 17. This figure shows, in sequential chrornatogram form, the
thermal destruction of Kepone at temperatures up to 910 C.
In this laboratory work, it was felt desirable to obtain the entire series of
analytical data at a fixed detection sensitivity S-o that the display of the various
chromatograms could be more easily compared. Consequently, signal
attenuation was maintained constant throughout the work. The quantitative
data were obtained from GC peak height measurements -- the preferred
method [20, 21] when one is comparing partially superimposed GC elution
profiles.
The compiled GC data obtained with HFID and the Tenax-GC trapping medium
are given in Table I. From these data, thermal destruction plots were
prepared for Kepone, Mirex, and DDT. These plots are presented in Figures
18, 19, and 20, respectively. Also, Figure 21 shows a direct comparison
of the high-temperature destruction of Kepone, Mirex, and p,p'-DDT.
Before proceeding with the presentation of further results, it is interesting
to note that Mirex undergoes a considerable degradation in the vicinity of
Z9
-------
GAS CHROMATOGRAPHIC CONDITIONS
Instrument
Analyst
Date
Tracer 550
W. Rubev
3-15-76
Column:
tubing material Pvrex
tubing length i.g
tubing bore 3. 5
meters
mm
Stationary Phase py. i silicons
weight 3%
Support r.hromosorb-W. HP Grade
mesh 100/120
Carrier Gas Helium
inlet pres 1. 8
linear velocity 10
outlet How 65
Chart Advance
Read Out
Sample
size
0.5
1.0
mv
abs atm
cm/sec
ml/mln
cm/min
full scale
Pesticides
Noted
Detector
range 10 ' AFS
attenuation 16
Gas Flows, ml/min
hyd rogen 50
air 350
split ratio none
Temperatures, °C
detector 320
injector
RT
column:
initial
final
40
260
14
progam rate
Sample Solvent Acetone + Benzene
C/min
concentration Noted
% solvent
Figure 13. Programmed Temperature GC Analysis Conditions.
30
-------
-ACETONE
-BENZENE
T2 = 433°C
UJ
CO I
o
Qu
to
QUANTITATIVE STANDARD
(4p.g, n-c|8)
fift KEPONE
\
0 START OF
1 TEMPERATURE
111 PROGRAMMING
'[ '.,,/ .-.<$
(f
®
c)
L
1 1 1 1 1
0 5 10 15 20 2
1 1 1
5 30 35 40
TIME, min
Figure 14. Chromatogram of Thermally Stressed Kepone.
31
-------
.ACETONE
-BENZENE
T2 - 599°C
LJ
OT ,
o
a.
a:
QUANTITATIVE STANDARD
, n-c,8)
MIREX
1
0
1
5
I
10
1
15
20
I
25
I
30
I
35
1
40
TIME, min
Figure 15. Chromatogram of Thermally Stressed Mirex.
32
-------
-ACETONE
•BENZENE
T2=382°C
Ui
-------
Kc
c/ ct
V-^ 7"^*
ct c./
\
Kc
T2 = 397°C
Ko
_
LJ.
o>
1
X
Cfl
LJ
CL
CO
LU
tr
-
Q
K\
T2 = 302°C
Q
Q
(QUANTA
I STD. /
CALIBRATION
SAMPLE
^ 9
K
1 KC
1 1.
i
i
K ; K^
1
\
\
1
1
, KQ
, i
fJ V
1 "Ar"
i 1 T
K.KEPONEi " " .
\ r(
Q
T2 = 9IO°C
Q
T2 = 807°C
Q
T2 = 708°C
Q
T2= 603°C
&
.T
Q
T2=495°C
Kb
a
Q
T2 = 463°C
Kb
\ k
L/K
',
>
i
i
Q K
T2= 435°C
Kb
^
I I
05
10 15 20 25 30
TIME,min
Figure 17. Series of Chromatograms from Thermally Stressed Kepone.
34
-------
TABLE I
High Temperature Exposures and Corresponding Analytical Data
Average Furnace
Temperature- -T
CC)
23*
302
397
435
463
495
603
708
807
910
Calculated Mean
Residence Time--t
(sec) r
Gas Chromatographic
Peak Height
-------
E
o
ul
CO
o
Q.
V)
UJ
tr
X
o
UJ
X
UJ
OL
O
X
Q.
<
-------
E
o
ul
CO
o
CL
CO
Ul
oc
o
LU
I
LU
O.
Q
Q.
O
1-
O
tr.
3:
o
100
30
10
3.0
1.0
0.3
O.I
0.03
0.01
MIREX
Mc;
^
\
\
\
\
200 400 600 800
TEMPERATURE, °C
1000
Figure 19. Thermal Destruction Plot for Mirex.
37
-------
100
E
o
UJ
-------
100
o
z
? 80
UJ
cc
60
UJ
o
2 40
H
-------
600 to 700 C. Also, upon re-inspection of the series of Kepone GC traces
(Figure 17), it is noticed that in the 700 C region, a large variety of decom-
position products are present. In order to confirm this complex high -
o
temperature behavior, Kepone was re-examined at 705 C and the previous
results were verified. The significance of the 700 C behavior of both Kepone
and Mir ex will be dealt with later.
Additional high-temperature destruction tests were conducted with Kepone,
; o '«
Mirex, and DDT samples at 900 C. The 'effluents from these tests were
passed through charcoal (previously cleaned with carbon disulfide) which
was then chemically desorbed with a mixture of acetone (44 vol%)j benzene
(44 vol%), and: carbon disulfide (12 vol%). The results of these 900°C '
examinations are presented in Table II, along with the analytical conditions.
The chromatographic peaks designated K and M were determined to be the
same compound, as they showed exact retention properties on two, quite
different GC columns. Further investigation with pure reference'standards
identified K and M as being hexachlorobenzene (C,C1, ). Another set of
peaks, K and M, , were also determined to be the same compound, and then
a D
subsequently identified as-hexachlorocyclopentadiene (C Cl,). It is interesting
to note that these two decomposition products are formed at different tem-
peratures, i.e., hexachlorocyclopentadiene is formed at 400 C to 600 C,
while hexachlorobenzene is present in the 500 to 900 C effluents.
Differential Thermal Analysis,,
Each of these pesticides was' subjected to a differential thermal analysis
while in air using a DuPont 900 DTA instrument. The test conditions and
resulting DTA tracings are presented in Figure 22. It is important to note
that each of these pesticides shows no thermal reactivity above 600 C. Thi
is reasonable, as one would not expect any endotherms or exotherms
40
-------
TABLE II
ECD ANALYSIS OF 900"C EFFLUENT
Sampl e
Kepone, 40 jig
Mirex, 40 [±g
DDT, 40 |ig
Pesticide Destruction,
Pesticide Extracted Pesticide
From Effluent Trap Destruction ("),)
138 pg >99. 9995
543 pg >99. 998
None Detected >99. 9998
r / \i
ft -100 1 /wt, trap extract \
\wt, input sample/ I
Other Trapped
Products
~200 ng
Hexachlorobenzene
~-400 ng
Hexachlorobenzene
Only Trace
Quantities
GAS CHROMATOGRAPHIC CONDITIONS
Instrument Varian Z44Q
Analyst W. Rubey
Dat e March 10, 1976
C olurnn:
tubing material
tubing length
tubing bore
Py vex
2. 0
3.0
Stationary Phase 1.5%QV-17-t- >. Q5".. QF- 1
w e ig ht noted
Support pas Chrom Q
nesh
8Q/10Q
Carrier Ga s__
inlet pres
I t_r pg e_n__
1 . 0
linear velocity
outlet flow ;
Chart Advance
Read Out \. Q
1.27
abs atrn
cm/ sec
ml/min
cm/Tnin
full scale
Sample Resjdue
size
Detector_
range
2. Q !
10
attenuation
Gas Flows, ml/min
hydrogen _
air
split ratio_
Temperatures, °C
detector 275
injector_
column:
240
initial
final
220
220
progam rate
°C/min
Sample Solvent Acetone + Benzene + CSa
concentration 994 % solvent
41
-------
DTA CONDITIONS
instrument
Reference
Crucibles
Thermocouples
Atmosphere
Temperature Program
duPont Model 900
Alumina
Platinum
Platinum vs Platinum + 13% -Rhodium
Dried Air
Ambient to 900°C at 20°C/min
KEPONE
(I5mg)
EXO
396-C 580.c
TEMPERATURE
25«C
ENDO
900°C
DDT
(I5mg)
MIREX
(lOmg)
EXO
I28"C
ENDO
4I6°C
570°C
TEMPERATURE
401°C
900°C
Figure 22. DTA Tracings of the Three Pesticides.
42
-------
occurring for pure, organic pesticides at the higher temperatures. How-
ever, it is observed that thermal reactions are occurring at temperatures
in excess of those found in the TG examinations. The explanation for this
difference is that the TG analyses were performed in a 60 ml/min flow of
purging air, while the escape of volatiles, or decomposition products, in
the DTA was mainly by diffusion into a moving air stream.
Earlier DTA data [22] for various pesticides reported high temperature
regions of thermal activity; however, such behavior has to be associated
with inorganic impurities, or incorporated clays, fillers, etc.
Effect of Pesticide Residence Time
The thermal breakdown of Kepone is pronounced in the 420 to 440 C region.
Consequently, this temperature region was selected for an experimental
evaluation of the effect of residence time on the destruction of Kepone.
Accordingly, three separate tests were conducted with 40 )Jg samples of
Kepone at a carefully controlled T_ of 433 C. The first test was conducted
£t
with a residence time, t , of 1. 79 sec. The t for the second test was
1. 04 sec, while for the third test, t was 0. 23 sec. These different resi-
dence times were obtained by appropriately adjusting the air flow control
valve of the quartz tube apparatus. Figure 23 shows each of the chromato-
grams which were obtained from the captured effluents. From these GC
data, the concentrations of emerging Kepone were plotted versus residence
time, as shown in Figure 24. Thus, it is evident from this logarithmic plot
that residence time is a strong factor in the destruction of Kepone at 433 C.
43
-------
SOLVENTS
QUANTITATIVE
RESPONSE
STAN
LJ
UA™, tr- 1.79 sec
^ l8 T2=433°C
'KEPONL
11
0 5 10 15 20 25 30 35
TIME,min
SOLVENTS
LJ .
CO
z
2
CO
LJ
cc
.
0
tr -1. 04 sec
© (i<) T2=43-3°C
' tp ©
1 '-' I 1
®
1
i F = — : — i 1 1 i 1
5 10 15 20 25 30 35
TIME , min
LJ
CO
Z
o
CL
co
UJ
cc
®
SOLVENTS
10 15 20 25 30
TIME , mm
35
Figure 23. Chromatograms Showing Kepone Levels.
44
-------
100
80
60
KEPONE
(WT %)
40
20
O.I
T2 = 433°C
i i
J L
0.3 1.0 3.0
(tr)
RESIDENCE TIME, SEC
10
Figure 24. Effect of Residence Time on Thermal Destruction of Kepone.
45
-------
Destruction of Kepone
From the presented experimental data, it is observed that Kepone can be
vaporized in flowing air at temperatures ranging from approximately 200 to
300 C. It is also observed from the series of chromatograms in Figure 17,
that this temperature range is not destructive to the Kepone molecule.
o
However, when Kepone is subjected to temperatures above 350 C, decom-
position does occur as is evidenced by the rapid drop in the Kepone concen-
tration shown in Figure 18. Eaton et al [23] have suggested that this lower
thermal stability of Kepone relative to the chemically similar Mirex is due
to the presence of Kepone's carbonyl group. Also, from the series of
chromatograms shown in Figure 17, it is seen that the thermal degradation
of Kepone at exposure temperatures less than 600 C is markedly different
from that which occurs when Kepone vapor is instantaneously subjected to
a temperature greater than 600 C. For example, peak K , which was
a
identified as hexachlorocyclopentadiene, was formed at temperatures below
500 C; however, it was not found above 600 C. Conversely, K , which was
determined to be hexachlorobenzene, was observed only in the products of
tests conducted above 600 C.
From the experimental data presented in Figure 24, the effect of residence
time on the destruction of Kepone vapor is indeed a strong factor, at least
in the 433 C region. Further work is required to determine the effect of
Kepone residence time at other exposure temperatures.
When Kepone vapor (in an excess of flowing air) is subjected to a 900 C
environment for approximately one second, it is observed that essentially
only hexachlorobenzene is found in the effluent. And, at this temperature,
hexachlorobenzene is only present in trace levels as indicated in Table II.
From results to date, it would appear that this molecule has considerable
thermal stability. However, the residence time of hexachlorobenzene at
46
-------
900 C has not been established in this study, as one does not know at what
point in the Kepone travel through the quartz tube that hexachlorobenzene
was formed. To determine the high-temperature destruction properties
of hexachlorobenzene, samples of the pure material would have to be
deposited at the inlet of the quartz tube and evaluated in the same manner
as were the three pesticides.
Destruction of Mir ex
The thermal destruction of Mirex has been studied by numerous investigators
[24-32]. Thus, a considerable body of information already exists on the
thermal behavior of this compound.
From the information obtained in the experimental work, it was found that
Mirex could be vaporized into a flowing air stream at temperatures as low
o
as 230 C. From the data presented in Figure 19, it is observed that Mirex
decomposes in the 600 to 700 C region. It is also observed from this same
figure, that the decomposition product M follows approximately the same
contour as K in the Kepone examination. In fact, both of these decomposi-
tion products have been identified as being the same compound, hexachloro-
benzene. Further study of the evolved products revealed that another com-
pound was common to the decomposition products of Kepone and Mirex, and
is designated as chromatographic peaks K and M, . This component,
hexachlorocyclopentadiene, was discussed earlier with regards to Kepone
o
where it was found only in the tests conducted below 500 C. In the Mirex
work, however, it was observed only in the 600 C testing.
The destruction of Mirex at 900°C is similar to that of Kepone. However,
the degree of destruction for Mirex is just slightly less than that found for
Kepone.
47
-------
Destruction of DDT
DDT has probably been subjected to more thermal decomposition testing
than any other pesticide. Also, the behavior of DDT in the environment has
been subjected to numerous studies.
In this experimental work with DDT, it was found that p, p'-DDT starts to
thermally decompose at much lower temperatures than Kepone or Mirex
(see Figures 20 and 21). The data presented in Figure 20 shows the con-
version of the DDT molecules to their respective DDE products. This
thermal conversion seemingly follows the same degradation path as the
metabolic conversion which occurs over a long period of time in soil and
water. From the data presented in Figure 20, it would appear that this is
a quantitative conversion from p, p'-DDT to p, p'-DDE and o, p'-DDT to
o,p'-DDE. Also, the thermal testing of DDT at 900°C (see Table II) ini
cated a complete destruction of DDT and DDE compounds.
It is interesting to note that apparently DDE is much more thermally stable
than DDT. It has also been reported [33] that DDE is considerably more
toxic to phytoplankton than DDT. Thus, for adequate thermal disposal of
DDT, one must be certain that there is both sufficient temperature and
residence time necessary to destroy not only the parent molecules, but also
their toxic decomposition products.
48
-------
Appendix I.
Error Analysis of Mean Residence Time Distribution.
Earlier, equation (V. 6) described the mean residence time of a substance
as it passed through a high-temperature quartz tube. This residence time
equation,
(A.I.I)
contains many variables, some of which have a pronounced effect on t and
are difficult to measure.
Upon investigation, it is found that fused quartz has a very small coefficient
of expansion (approximately 0. 59 x 10 ). Therefore, for a given tube, the
radius r and the length L can be assumed temperature invariant. Thus,
the effective volume of a specific quartz tube, i.e.,
(A.1.2)
remains essentially constant.
Further, the laboratory temperature T and pressure p can be easily and
accurately measured. However, the outlet ambient flow rate F , the aver-
o
age oven temperature T , and the system differential pressure p require
special measurement equipment.
The maximum change in t which can be attributed to an addition of errors
in F , T_, and p , can be expressed as
o £• d
At
(A.I. 3)
49
-------
From equations (A.I. 1) and (A. I. 2), we find
(A.I. 4)
at
r ' " -"' •"•-• (A.I. 5)
at v T
d F T,p
o 2 o
Now the maximum errors typically associated with the selected measure
ment methods are
AF = F x 10~ cm sec"
o o
AT = 5°K
LJ
_3
Ap = 5 x 10 atm
Next, an example case is presented where
t =1.0 sec
r
F =1. 235 cm sec
o
T = 296°K
o
T = 873°K
p = 0.974 atm
o
p, = 0.2 atm
a
V. = 3.021 cm3
50
-------
By substituting into equation (A.I. 3) the data for this case and the typical
measurement errors, the worst condition is found to be
At
At
(temperature)
At
(pressure)
(flow)
I I I
0.00999 + 0.00575 + 0.00426
Thus,
At
= 0.020
or, the maximum relative error in t is 2.0%.
r
With this instrumentation, the flow measurement possesses about twice the
effective error in t as the temperature or pressure measurement. Also,
upon further examination, it is observed that At /t is essentially unaffected
by the broad temperature range and the various residence times.
Consequently, this error analysis shows that the individual measurement
errors encountered in determining t are small and in the same domain.
51
-------
Appendix II.
Pesticide Residence Time Distribution.
The longitudinal dispersion of a gas as it passes through an open cylindrical
tube has been thoroughly studied [34, 35] . Consequently, in the absence of
a retentive or interactive wall surface, the variation in transport of like
molecules can be expressed by
d(CV2 2Dg vr2
H s - - ~+
where H is the height equivalent to a theoretical plate (as commonly utilized
in chromatography), a is the distribution standard deviation in distance
X
units, x is distance, D is the intermolecular diffusion coefficient, v is the
O
average linear velocity of the gas, and r is the radius of the open cylindrical
tube.
From equation (A. II. 1) we can write
rL/v\
* I (nn~ldx ' (A.II.2I
,•/ J<> rv
and, at distance x = L
2D L _ 2,
(ffx) ^ —~ + g- . (A. II. 3)
Now, for like pesticide molecules that are randomly entering and passing
through a narrow bore tube, the variation in residence time can be repre-
sented by a Gaussian distribution with a time-based independent variable.
Thus, it is necessary to convert a to a time-based sigma value. This is
X
readily accomplished as
(O = (°J (?) • (A. II. 4)
52
-------
Equation (A. II. 3) can now be rewritten as
2,
(A. II. 5)
or
(A. II. 6)
The intermolecular diffusion coefficient has been equated by Reid and Sher
wood [36] as
where P is pressure, T is temperature, d is distance.between the molecular
centroids, M and M_ are the respective molecular weights, and b is a con-
1 Lt
stant.
Due to the absence of high-temperature diffusion data for pesticides in "air,
it was necessary to select a model compound for which D data did exist.
O
Calculated D data could then be obtained with the use of equation (A. II. 7)
O
for the entire range of pesticides.
The selected model compound was naphthalene. This substance is low
enough in molecular weight that D data are available, e.g. , D for naphtha-
2-1
lene in air = 0.0611 cm sec" at 298°K and 1.0 atm [36], and it is a common
household pesticide. Also, naphthalene is structurally similar to other
fused-ring pesticide compounds, e.g., aldrin, carbaryl, dichlone, dieldrin,
endrin, and the halowaxes.
53
-------
Next, from the diffusion expression, i.e., equation (A. II. 7), it is observed
that
5D T(M +M )
-
Therefore, even with fixed values of P, r, L, and residence time, O will
continue to vary with temperature and M (the molecular weight of the
pesticide).
To clarify this situation, residence time distribution data, as represented
by
-------
(a)
0.04
0.03
-------
intermolecular diffusion coefficient increases with temperature, the pesti-
cide resident
temperature.
cide residence time distribution, as represented by a , decreases with
Figure 25b shows the variation of a with t for naphthalene. Upon further
investigation it is determined that the term 4(7 /t varies only by a factor of
two over the residence time range of 0.3 to 2.0 seconds. Thus, the relative
change in (T with t is tolerable.
Lastly, it is important to note that
-------
REFERENCES
1- Occupational Safety and Health Reporter, J>, No. 35, pp. 1164-1167,
January 29, 1976. ~
2. Raloff, J. , Chemistry, _49, No. 4, 20 (1976).
3. Ferguson, T.L., Bergman, F. J., Cooper, G, R., Li, R.T., and
Honea, F. I., Determination of Incinerator Operating Conditions
Necessary for Safe Disposal of Pesticides, EPA 600/2-75-041,
December 1975.
4. Kennard, E.H., Kinetic Theory of Gases, McGraw-Hill, New York,
1938, Chap. I.
5. Sternberg, J. C., Advances in Chromatography, Vol. 2, (Giddings, J. C.,
and Keller, R. A., eds. ) Marcel Dekker, New York, 1966, Chap. 2.
6. Sutton, R., and Harris, W. E., Can. J. Chem., 45; 2913 (1967).
7. Barr, W. E., and Anhorn, V.J.. Scientific and Industrial Glass
Blowing and Laboratory Techniques, Instrumentation Publ. Co. ,
Pittsburg, 1949, p. 198.
8. Fairbairn, J. W. , and Relph, S.J., J. Chromatog., 33, 494(1968).
9. Novotny, M., Lee, M. L., and Bartle, K. D., Chromatographia,
]_, 333 (1974).
10. Zlatkis, A.,Lichtenstein, H. A., and Tishbee, A., Chromatographia,
JD, 67 (1973).
11. Bertsh, W. , Chang, R. C., and Zlatkis, A., J. Chromatog. Sci.,
YZ, 175 (1974).
12. Bellar, T. A., and Lichtenberg, J. J., EPA-670/4-74-009,
November 1974.
13. Leoni, V., Puccetti, G., and Grella, A.. J. Chromatog., 106, 119,
(1975).
14. Pellizzari, E. D., Bunch, J. E., Carpenter, B. H., and Sawicki,
E., Environ. Sci. Tech., _9, 552 (1975).
57
-------
15. Pellizzari, E. D. , Carpenter, B.H., Bunch, I.E., and Sawicki, E.,
Environ. Sci. Tech., _9, 556 (1975).
16. Parsons, J.S., and Mitzner, S.. Environ. Sci. Tech., _9, 1053
(1975).
17. Grob, K., and Grob, G., J. Chromatog., 62, 1 (1971).
18. Otterson, E. J., and Guy, C. J., Trans. Twenty-Sixth Ann. Meeting
A. C.G.I. H., 37 (1964).
19. Levy, A., J. Sci. Instru. 4J., 449 (1964).
20. Rubey, W. A., Univ. of Dayton Res. Inst. Technical Report
No. UDRI-TR-72-117, April, 1972.
21. Janik, A., J. Chromatog. Sci., 13, 93 (1975).
22. Kennedy, M. V., Stojanovic, B. J., And Shuman, F. L., Jr., Residue
Rev., 29, 89 (1969).
23. Eaton, P., Carlson, E., Lombardo, P., and Yates, P., J. Org.
Chem.. _25, 1225 (I960).
24. Alley, E.G., Layton, B. R., Minyard, J.P., Jr., J. Agr. Food
Chem., 22, 442 (1974).
25. Ivie, G. W. , Dorouga, H. W., Alley, E.G., J. Agr. Food Chem.,
22, 933 (1974).
26. Alley, E.G., Layton, B. R., paper presented at the 16 5th National
Meeting of the American Chemical Society, Dallas, Texas, April 9-
13, 1973.
27. Holloman, M. E., Layton, B. R., Kennedy, M. V., and Swanson,
C.R., J. Agr. Food Chem., 23, 1011 (1975).
28. De La Cruz, A. A., and Naqvi, S. M., Arch. Environ. Contain, and
Toxicol., _!, 255 (1973).
29. Stein, V. B., Pittman, K. A., and Kennedy, M. W., Bull. Environ.
Contain, and Toxicol., 15, 140(1976).
30. McBee, E. T., Roberts, C. W., Idol, J. D., Jr., Earle, R. H., £.
Am. Chem. Soc., 78, 1511(1956).
58
-------
31. Dilling, W.L., and Dilling, M.L., Tetrahedron, 23, 1225(1967).
32. Alley, E.G., J. Environ. Qual., Z, 52 (1973).
33. Powers, C. D., Rowland, R. G. , Michaels, R. R., Fisher, N. S. ,
and Wurster, C. F., Environ. Pollut., _£, 253 (1975).
34. Taylor, G. , Proc. Roy. Soc., A, 219, p. 186 (1953).
35. Golay, M. J.E., Gas Chromatography 1958, (Desty, D. H., ed. )
Butterworths, London, 1958, p. 36.
36. Reid, R. C. , and Sherwood, T. K., The Properties of Gases and
Liquids, McGraw-Hill, New York, 1958, Chap. 8.
59
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-299
3. RECIPIENT'S ACCESSIOWNO.
4. TITLE AND SUBTITLE
LABORATORY EVALUATION OF HIGH-TEMPERATURE DESTRUCTION
OF KEPONE AND RELATED PESTICIDES
5. REPORT DATE
December 1976 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
D. S. Duvall
W. A. Rubey
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
University of Dayton Research Institute
300 College Park Avenue
Dayton, Ohio 45469
10. PROGRAM ELEMENT NO. 1DC618
SOS# 6, Task 03
11. CONTRACT/GRANT NO.
R-803540-01-0
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory - Cin., OH
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Richard A. Carnes (Project Officer) 513/684-7871
16. ABSTRACT
Thermal destruction testing was conducted with three pesticides: Kepone, Mi rex,
and DDT. A specialized laboratory technique incorporating a two-stage quartz
system was developed. It is important to note that in this system the pesticide
was first converted to the gas phase, then exposed to the high-temperature
destruction conditions. Critical parameters of temperature and residence time
were accurately measured. Both the Kepone and DDT molecules, at a residence
time of ^1 second, were essentially destroyed at 500°C; however, Mirex, at the
same residence time, required 700°C for destruction.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
*Pesticides
Detoxification
Temperature
Degradation
Recombination Reactions
Research
Retention Time
Excess Air
13B
S. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
70
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
60
6USGPO: 1977 — 757-056/5480 Region 5-11
------- |