DTIC ADA328066: Adsorption of Chloroform by the Rapid Response System Filter.

31 Pages·1 MB·English

by  Defense Technical Information Center

O
EDGEWOOD
PUSEACH. D(cid:127)V(cid:127)LOPM:E.''T & EX(cid:127)rUEERiNG CENTER
U.S. A-v3rf C EMCA .A(cid:127) D BIOLOGIC.AL DEFENSE cOMMAND
ERDEC-TR-357
ADSORPTION OF CHLOROFORM
BY THE RAPID RESPONSE SYSTEM FILTER
Christopher Karwacki
Paulette Jones
RESEARCH AND TECHNOLOGY DIRECTORATE
January 1997
A
Approved for public release; distribution is unlimited.
Abecd.een Proving- Gr-ound, MD 21010-5-42-3
Disclaimer
The findings in this report are not to be construed as an official Department of the Army
position unless so designated by other authorizing documents.
DEPARTMENT OF THE ARMY
U.S. Army Edgewood Research, Development and Engineering Center
Aberdeen Proving Ground, Maryland 21010-5423
ERRATUM SHEET
15 December 1997
REPORT NO. ERDEC-TR-357
TITLE ADSORPTION OF CHLOROFORM BY THE RAPID
RESPONSE SYSTEM FILTER
N AUTHORS Christopher Karwacki, and Paulette Jones
SDATE
January 1997
S CLASSIFICATION UNCLASSIFIED
Please remove the front cover from copies of ERDEC-TR-357 sent to
you earlier in 1997 and attach the enclosed replacement cover.
Previously printed covers were inadvertently printed with the
incorrect activity name and logo.
SA4LDRAJQLýNS
Chief, Technical Releases Office
Z<1
REPORT DOCUMENTATION PPAFGorEm OMB ANop.p r0o7v0e4d-0188
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions searching existing data sources,
gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson
Davis Highway, Suite 1204, Arlington, VA 22202-4302. and to the Office of Management and Budget. Paperwork Reduction Project (0704-0180), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED
1997 January I Final, 95 Apr - 95 Jun
4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
Adsorption of Chloroform by the Rapid Response System Filter
PR-1 0262622A552
6. AUTHOR(S)
Karwacki, Christopher, and Jones, Paulette
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
REPORT NUMBER
DIR, ERDEC, ATTN: SCBRD-RTE, APG, MD 21010-5423 ERDEC-TR-357
9. SPONSORING /MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/ MONITORING
AGENCY REPORT NUMBER
11. SUPPLEMENTARY NOTES
12a. DISTRIBUTION /AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
13. ABSTRACT (Maximum 200 words)
Adsorption equilibria and dynamic breakthrough data were measured to determine the adsorption
capacity and effect of purge air on the desorption of chloroform from activated carbon simulating
the Rapid Response System (RRS) filter. The objectives of this investigation were to (1) estimate
the vapor concentrations of chloroform produced in the RRS decontamination process, (2) char-
acterize the breakthrough behavior of chloroform on activated coconut adsorbent used in the
RRS filter during feed and purge cycles, and (3) provide an estimate of filter life based on routine
RRS decontamination operations. Results of the investigation show chloroform vapor concen-
trations of approximately 1.3 g/m' can result during normal RRS decontamination operations.
Under normal operating concentrations, the maximum capacity of the filter is estimated at
925 g-min/m3 at 1.3 g/m 3 feed concentration and increases to 1732 g-min/m3 at 10.0 g/m3. The
filter's capacity and useful life are reduced significantly when purged with clean air after
exposure to chloroform. Either reducing or eliminating the purge air between operations can
increase the filter's useful life from 2 to 7 days.
14. SUBJECT TERMS 15. NUMBER OF PAGES
Desorption Chloroform 27
Adsorption Rapid Response System filter 16. PRICE CODE
17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT
OF REPORT OF THIS PAGE OF ABSTRACT
UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED SAR
NSN 7540-01-280-5500 Standard Form 298 (Rev 2-89)
Prescribed by ANSI Std Z39-18
Blank
2
PREFACE
The work described in this report was authorized under Project No.
10262622A552, the Rapid Response System (RRS) Program for Chemical Demilitarization
Nonstockpile. This work was started in April 1995 and completed in June 1995.
Experimental data are contained in laboratory notebook 95-0057.
The use of either trade or manufacturers' names in this report does not constitute
an official endorsement of any commercial products. This report may not be cited for
purposes of advertisement.
This report has been approved for public release. Registered users should request
additional copies from the Defense Technical Information Center; unregistered users should
direct such requests to the National Technical Information Service.
Acknowledgments
The author acknowledges John Walther and Michael Myirski for their work on
model predictions for chloroform evaporation rates and Brian Maclver for conducting
confirmational experiments.
3
Blank
4
CONTENTS
1. INTRODUCTION ............................................... 7
2. BACKGROUND ............................................... 7
3. EXPERIMENTAL METHODS ...................................... 9
3.1 Generated Chloroform Concentrations ............................ 9
3.2 Isotherms .. .............................................. 9
3.3 Dynamic Adsorption ........................................ 12
4. RESULTS AND DISCUSSION ..................................... 13
4.1 Glovebox Concentrations . .................................. 13
4.2 Adsorption Equilibria ........................................ 15
4.3 Chloroform Breakthrough . .................................. 18
4.4 Adsorption at 50% RH . .................................... 20
5. CONCLUSIONS . ............................................ 22
LITERATURE CITED . ......................................... 27
5
FIGURES
1 Single Pass Filter Diagram Used in RRS .............................. 8
2 Illustration of RRS Filter Produced by lonex Research
Corporation .. ............................................ 10
3 Schematic of Isotherm Apparatus . ............................... 11
4 Schematic of Dynamic Adsorption Apparatus ....................... 14
5 Isotherm of Chloroform on Coconut and BPL Activated Carbons .......... 16
6 Plot of Micropore Volume Plot of Coconut and BPL Carbons Using the
Dubinin-Radushkevich Equation . .............................. 17
7 Effect of Chloroform Dosage on Time to Breakthrough on Coconut
Carbon (<2% moisture) . ................................... 19
8 Breakthrough of Chloroform Fed Intermittently on Coconut Carbon
(<2% moisture) ........................................... 21
9 Chloroform Dosage on Time to Breakthrough for 8 x 16 Mesh Coconut
Carbon .. ............................................... 23
10 Breakthrough of Chloroform Following a 100-Min Dosage on Dry
and 50% RH Carbons ....................................... 24
TABLES
1 RRS Filter Specifications ........................................ 10
2 Properties of Chloroform Used in the D2 Evaporation Rate Model .......... 11
3 Test Conditions for Intermittent and Continuous Challenges ............. 12
4 Estimate of Chloroform Concentration (Normal Operation) ............... 15
5 Filter Dosages as a Function of Operation Time per Day ................. 15
6 Equilibrium Capacities of Chloroform on Coconut and BPL Adsorbents ...... 20
6
ADSORPTION OF CHLOROFORM BY THE RAPID RESPONSE SYSTEM FILTER
1. INTRODUCTION
"Thef iltration of contaminated airstreams is one of several critical stages involving
the detoxification of nonstockpile materiel performed by the Rapid Response System
(RRS). A major concern during routine operations is to maintain adequate engineering
controls to prevent releasing hazardous compounds into the environment. One approach is
to use a single pass adsorption unit containing activated carbon to remove vapors that can
vent from the decontamination vessel. Typical operations may involve the decontamina-
tion of mustard and lewisite with organic oxidants in the presence of chloroform and tert-
butyl alcohol, which are used as solvents.
Of all chemicals used, chloroform, which will be present in significant quantities,
may offer the greatest burden to the RRS filter. Chloroform's removal by activated carbon
is limited to physical adsorption (no chemical reaction); and, due to its high vapor pressure,
the propensity exists for the vapor to desorb from the adsorbent bed during air purge.1
The extent of desorption is dependent upon the adsorption capacity of the adsorbent, the
adsorbed phase loading, temperature of the bed, purge volume, and the presence of other
adsorbed materials (i.e., water). The adsorption behavior is primarily governed by the
equilibrium concentrations of chloroform adsorbed at some fluid phase concentration. In
this investigation, adsorption equilibria and dynamic breakthrough data were measured to
determine the effect of purge air on desorption of chloroform from activated carbon. Test
conditions were limited to parameters simulating the RRS filter. The effects of
concentration, dosage, flow rate, purge volume, and relative humidity (RH) were
examined. The influence of other adsorbed chemicals, other than moisture, was not
determined.
The objectives of this investigation were to (1) estimate the vapor concentrations
of chloroform produced in the RRS decontamination process, (2) characterize the break-
through behavior of chloroform on activated coconut adsorbent used in the RRS filter
during feed and purge cycles, and (3) provide an estimate of filter life based on routine
RRS decontamination operations.
2. BACKGROUND
RRS Filter Specifications.
The complete RRS filtration unit is designed to remove particulate and vapor
contaminants prior to releasing the airstream to the outside air. Four stages of vapor
filtration are used, where the first two filters contain coconut shell-based adsorbent, and
the latter contain standard CW agent-compatible adsorbent (Figure 1). The location of the
coconut carbon filters was intended to either reduce or delay the loading of nonagent
vapors to the CW filters. The CW filters were to adsorb (physical and chemical) agent
vapors, because this carbon is the only material with validated performance against this
class of vapors. Filters one and two were selected to remove chloroform and initially other
nonagent vapors to reduce the loading of these vapors on the NBC filters (numbers three
7