SIMULANTS OF CHEMICAL WARFARE AGENTS FOR TESTS OF THERMAL DESORPTION TECHNOLOGY

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1 SIMULANTS OF CHEMICAL WARFARE AGENTS FOR TESTS OF THERMAL DESORPTION TECHNOLOGY Šváb M., Zápotocký L Dekonta,a.s., Dretovice 109, Stehelceves, Czech Republic svab@dekonta.cz Abstract Chemical warfare agents (CWA) represent specific toxic species which are still stored, possibly produced and, however, its misuse cannot be excluded, what was proven by number of incidents, recently. Although this potential danger is taken into the account seriously by authorities, usually the security measures focus only on instantaneous reaction on the unwanted situation occurred. Residual solid materials (concrete, masonry, soil, etc.) affected by low volatile CWAs, then, still represent an additional source of potential danger. Such materials should be decontaminated. Thermal desorption technology is an efficient method which can be suggested for cleanup of such materials. According to the above described assumptions, low-volatile agents should be considered as of a great importance. Mainly some nerve agents and vesicants with boiling point between C fit to assumed parameters. Nevertheless, it is necessary to verify an efficiency of traditional remediation technologies in application on removal of the CWAs. However, from many reasons it is highly required to exclude an experimental work with the real CWAs. Thus, the CWAs must be replaced by harmless chemicals, which, on the other hand, have similar key physical-chemical properties for the purpose of desired experiments. In our contribution, we would like to provide a brief introduction to the topic of CWAs as potential residual contaminants of solid matrixes, and discuss selection of possible simulants for the experimental work. The interaction of CWA simulants with various solid matrixes and problems caused by its hydrolysis will be discussed in experimental part. Introduction Chemical warfare agents (CWA) are solids, liquids, or gases, which, through their chemical properties, produce lethal or damaging effects in man, animals, plants, or materials. Historically, chemical agents have been divided into categories based on the major physiological impact caused by the agent or the target organ they attack. Nerve agents disrupt the function of the nervous system and produce effects on skeletal muscles, various sensitive organs, and the nervous system. Blister agents, also known as vesicants, affect the eyes, lungs and skin by destroying cell tissue. Blood agents are compounds which affect the ability of the blood system to either carry oxygen or transfer oxygen from the blood to cells. Choking agents are compounds that can cause the lungs to become filled with fluid. Incapacitating agents produce physiological effects that inhibit concerted effort. Tear agents cause intense eye pain and tears. Vomiting agents cause regurgitation 1. Thousands of chemicals widely used in industry have been evaluated by various militaries for their possible use as chemical warfare agents and many have even been employed in combat. However, with the discovery of the more toxic nerve and blister agents, the use of most of these materials has been abandoned 1. Although the CWAs represents an instant danger for human health and are usually taken into account in this way, it represent subsequent source of risk also later its use (dispersion). Thus, effective and safe remediation technology must be applied for its removal from polluted matrixes (later on the first aid for affected people and similar actions etc.). From the point of view of residual contamination, the CWAs which are liquid/solid and low-volatile are important since they are able to remain in exposed matrixes (masonry, soil etc.). The technology which can be effectively employed for the CWAs-polluted matrixes clean-up can be based on the thermal desorption under lower pressure what prevent leak of the CWAs out from the system. However, although the thermal desorption is already used for the removal of environmental pollutants from solids, it is necessary to verify and optimize the process parameters in case of CWAs removal through experiments. However, exclusion of the real CWAs from the experimental work is needed; thus, suitable non-toxic chemical surrogates must be found.

CWAs of interest CWAs of interest means the CWA which are low-volatile (potentially remaining in exposed solids) and can also be expected considering its misuse.

Table 1 Typical representatives of the low-volatile CWAs 2 (selection): Nerve agents other name chemical name names Sarin Soman GB. T-144. Trilon 46. EA 1208 GD. VR-55.

2 CWAs of interest CWAs of interest means the CWA which are low-volatile (potentially remaining in exposed solids) and can also be expected considering its misuse. In first, gaseous or high-volatile species are excluded. In table 1, typical representatives of the low-volatile CWAs are summarized. Table 1 Typical representatives of the low-volatile CWAs 2 (selection): Nerve agents other name chemical name names Sarin Soman GB. T-144. Trilon 46. EA 1208 GD. VR-55. EA 1210 Isopropyl methylphosphonofluoridate Pinacolyl methyl phosphonofluoridate melting point ( C) boiling point, ( o C) VX VX (USA). EA 1701 O-Ethyl-S-(2- diisopropylaminoethyl) methyl phosphonothiolate (dec.) Vx Vx. R 33 (Rus.). Medemo. EDMM. EA1699 O-ethyl S-(2- dimethylaminoethyl) methylphosphonothiolate Ned. 256 Tabun GA. EA Trilon 83 Ethyl N. N- dimethylphosphoroamido cyanidate GF. CMPF Cyclosarin EA T Blister agents (vesicants) other name names H. Yperite gas. HD. gas 1 HS. EA 133 HN-1. Ethyl S. NH-Lost. NSC TL 329. TL 1149 HN-2. dichloren. NSC 762. TL 146. T ENT MBA Cyclohexyl methylphosphono fluoridate chemical name melting point ( C) Bis (2-chloroethyl) sulfide Cl-CH 2 -CH 2 -S-CH 2 -CH 2 -Cl 14 boiling point. ( o C) (dec.) 2.2 -Dichlorotriethylamine Bis-(2- chloroethyl)methylamine

3 Lewisite Sternite Green Cross 3 Medikus HN-3. TS 160. EA 1053. TO. TL 145. TS 160 L. L-1. M-1. EA 1034 2. 2. 2 - Trichlorotriethylamine Dichloro (2-chlorovinyl)arsine -4 257 (dec.

3 3 Lewisite Sternite Green Cross 3 Medikus HN-3. TS 160. EA TO. TL 145. TS 160 L. L-1. M-1. EA Trichlorotriethylamine Dichloro (2-chlorovinyl)arsine (dec.) (dec) PD. Pfiffikus. DJ. TL 69. FDA Phenyldichloroarsine -23 >255 ED. Dick. TL 214. Yellow Ethyldichloroarsine < Cross 1 MD. TL 294. Methyl-dick Methyldichloroarsine CX Dichloroformoxime Choking agents other name names chemical name melting point ( C) boiling point. ( o C) Difosgene DP. Perstoff. Superpalite. Surpalite Trichloromethyl chloroformate Phosgenoxime Chlorpicrine PS. KLOP trichloronitromethane Cl Cl C Cl NO 2 It would be speculative to estimate which CWAs should be expected for potential misuse. However, there are several relevant literature sources available related to this question including the reviews 3, 4. In such sources, following CWAs are mostly mentioned: Tabun, Sarin, Soman, VX, Yperite, Lewisite. Furthermore, Gupta C.R.(2015) 5 published an expectations which CWAs might be expected as potential misused agents. These CWAs include: Sulfur s, s, Lewisites, Tabun, Sarin, Soman, VX, BZ, Opioids, CS, CN, CR, Chlorine, Phosgene, Cyanides and Ricin. This enumeration includes also RCAs (Riot Control Agents) which are not of interest. Considering above described facts (i.e. low-volatility and probability of misuse), we can conclude the set of the CWAs of interest. It is disclosed in the Table 2 including basic physical-chemical properties.

4 Table 2 Properties of the CWAs of interest 1,2 : name / M(g/mol) Sarin Soman VX Vx Tabun Látka GF Yperite gas Lewisite Boiling point, ( o C, 101 kpa) Decomp.temp, ( C) vapor pressure (Pa, 25 C) heat of vaporization (KJ/mol, 25 C) log (K ow ) / water solubility (g/l, 25 C) vapor density/air (2.5 h) / miscible (4-200 h) (minutes) / / na na (3.25 h) / (2 h) / / < / < / na < / (trans) < / Simulants of the CWAs of interest An ideal chemical agent simulant would mimic all relevant chemical and physical properties of the agent without its associated toxicological properties. Although a number of compounds have been used as CWAs simulants, no individual compound is ideal because a single simulant cannot satisfactorily represent all environmental fate properties of a given CWA. Thus, a number of different chemicals have been used as CWAs simulants depending on the physical chemical property of interest 4. The property of interest for the purpose of tests of the thermal desorption technology involves mainly boiling point (although it is not the only crucial parameter determining the treatability of the material by the thermal desorption), vapor pressure and partly also octanol-water partitioning coefficient and water solubility. Decomposition temperature might be also important. Based on these assumptions, many species was considered as surrogates for thermal desorption tests based on the literature review as well as on evaluation of molecular structure of similar compounds (=non-published surrogates). From this set of the chemicals, the group of suitable surrogates was selected. Selected surrogates and similar CWAs which could simulate are presented in the Table 3. Very similar CWAs (chemically/with respect to the properties) are excluded from the list in order to reduce amount of compared data.

5 Table 3 Potential surrogates and similar CWAs 4,6 : name / M(g/mol) Boiling point, ( o C, 101 kpa) Decomp.te mp, ( C) vapor pressure (Pa, 25 C) log (K ow ) / water solubility (g/l, 25 C) vapor density/air Sarin (2.5 h) / miscible 4.8 ECA CEES Acetoin na / na / na / miscible 3 Soman (4-200 h) / Lewisite (trans) < / DEEP / DEM na / Tabun (3.25 h) / DEA na / VX (minutes) / DEPh na / DES Yperite MS Cl-CH 2 -CH 2 -S-CH 2 - CH 2 -Cl > / 0.08 > / na /

6 Experimental Prior to thermal desorption experiments, it was necessary to verify methodology and analytics. For this purpose, we caried basic evaluation of interaction between CWAs simulants and the solid matrixes potentially treated by thermal desorption technology. The matrixes involved coarse waste, concrete rubble, clay, sand, soil and red clay (as brick material). The materials were ground, sieved (2 4 mm), air-dried and homogenized. Basic information about the matrixes is concluded in the Table 4. Results for simulant DEPh (diethylphtalate) will be presented below. It represents surrogate of very low-volatile CWAs (i.e.vx). Table 4 Matrixes used for experiments matrix coarse waste concrete rubble clay sand soil* red clay dry matter (%) ph *- TOC = 1.2 % Main aim of the experiments was to compare adsorption of the DEPh on the matrixes. Since DEPh, as an ester, tends to decompose in presence of water, the ethanol was used as solvent. Stock solution of the DEPh in ethanol (500 mg/l) was mixed with each matrix (solution of volume 500 ml, solid mass 250 g). Flasks were mixed for 24 hours to reach equilibrium. Then, liquid phase was separated by membrane filtration (0.45 µm). This operation was done quantitatively (including dry matter content of filtration cake) in order to calculate equilibrium adsorbed DEPh concentration in dry matrixes from analytical results obtained from analysis of dried (originally wet) sludge (matrix with rest of the ethanol solution). As a second step, the exposed matrixes containing DEPh was leached by water in order to examine how strongly the DEPh is bound into each matrix. The matrixes were mixed with distilled water in ratio of 1:10 for 2 hours. Then, the phases were separated similarly as in case of exposition to ethanol solution of DEPh (see above). The filtration cake was air dried for 2 days. The process was done quantitatively for possible mass balance calculation. Before analysis, the aqueous samples (100 ml) were extracted by mixture heptane/dichlormethane (9:1) under ph 2 for 5 minutes. The extract was then separated and diluted. Solid samples were extracted (1.5 g) by 10 ml of mixture acetone/hexane (1:2) in ultrasonic bath for 30 minutes. Extract was then separated by membrane filtration (0.45 µm) The extraction efficiency was tested on control sample and was considered in final evaluation (approx. 66 %). Method of internal standard was used for analytical determination using gas chromatography (Agilent Technologiies 6890N ) with mass detector (5975). Column was 30 m long, internal diameter 0.25 mm and film thickness of 0.25 µm (type SLB-5ms, Sigma Aldrich). Results The results of the adsorption tests are disclosed in the Table 5. Table 5 Adsorbed concentration of DEPh on various matrixes (similar initial conditions) matrix Equilibrium sorbed concentration (mg/kg dry matter ) coarse waste concrete rubble 81.8 clay sand 83.5 soil red clay The results disclosed in the Table 5 express only one point on adsorption curve. However, it allows comparison of adsorption of the DEPh on various matrixes. According to was could be expected, highest adsorption was

7 revealed in case of soil, what originates mainly from organic matter. Lower sorption was proven in case of clay and red clay, where it originates from thermal method of manufacturing of bricks. Lowest sorption was observed in case of other matrixes, also in agreement with expectations. After simplification, the increasing willingness of back release of the DEPh can be expected in the similar order. Subsequently, the exposed matrixes were then leached by water; its results are presented in the Table 6. Table 6 Adsorbed concentration of DEPh on various matrixes (similar initial conditions), mass balance of tests matrix DEPh conc. in leachate* (mg/l) leachate ph DEPh initial mass (mg) mass balance DEPh mass (leachate, mg) DEPh mass (residual sludge, mg) coarse waste concrete rubble clay sand soil red clay Concentrations of DEPh in leachates were affected by both the leachability from the matrix and hydrolysis. In addition, the hydrolysis was influenced by ph. This is why the mass balance showed low values. For example, the recovery of leaching test from the concrete rubble was only 20 %, what was given by alkali conditions promoting the alkali hydrolysis of the DEPh. Lowest recovery was observed in case of soil (15 %), but this value did not exceed 53 % for any matrixes. It is important to mention that hydrolysis run in liquid phase (2 hours) as well as in filtration cakes (2 days). Finally, the hydrolysis contribution to low recovery cannot be distinguished between liquid and solid phase, since its rate is affected also by ph value and overall composition. Thus, the hydrolysis makes the leaching behavior of DEPh unevaluable. In the thermal desorption experiments, it is necessary to exclude contact between simulant (or exposed matrix) and water in order to avoid similar evaluation problems. Conclusion It is possible to find suitable surrogates of the CWAs for tests of thermal desorption technology. Suitable surrogates are mainly based on esters. However, its hydrolysis complicates an experimental work and could make it unevaluable. It is necessary to exclude or minimize contact of such surrogates with aqueous phase. Acknowledgement This work was supported by Ministry of Interior VI1VS/292. References 1. Ellison D.H.: Handbook of Chemical and Biological Warfare Agents, CRC PRess, Boca Raton, 2000, ISBN: Department of the Army. Potential Military Chemical/Biological Agents and Compounds.FM 3-9, NAVFAC P-467, AFR Department of the Army, Navy and Air Force, Fort McClellan, AL, Lavoie J., Srinivasan S., Nagarajan r.: Using Cheminformatics to Find Simulants for Chemical Warfare Agents, Journal of Hazardous Materials 194 (2011), Bartelt-Hunt S.L., Knappe D.R.U.K., Barlaz M.A.: A Review of Chemical Warfare Agent Simulants for Study of Environmental Behavior, Critical Reviews in Environmental Science and Technology, 38 (2008), Gupta C.R.: Handbook Of Toxicology Of Chemical Warfare Agents, Academic press, Lavoie J., Srinivasan S., Nagarajan r.: Using Cheminformatics to Find Simulants for Chemical Warfare Agents, Journal of Hazardous Materials 194 (2011),

Compendium of Chemical Warfare Agents

Compendium of Chemical Warfare Agents Compendium of Chemical Warfare Agents Steven L. Hoenig Senior Chemist/Chemical Terrorism Coordinator Florida Department of Health Bureau of Laboratories-Miami Library