Impact of humidity on the adsorption and decomposition of mustard gas simulant on heteroatom-modified nanoporous carbon textiles

Activated carbon textile (C-Text) was chemically modified to incorporate oxygen- (C-Text-O), nitrogen- (C-Text-ON), and/or sulfur- (C-Text-OS) containing surface functional groups, aiming to enhance their reactive adsorption capacity. The modified textiles were evaluated for their ability to detoxify 2-choloroethyl ethyl sulfide (CEES) in both vapor and liquid phases, under dry and humid conditions. The maximum amount of water adsorbed was directly affected by the surface area (R² = 0.994) and total pore volume (R² = 0.986) of the textiles. Pre-adsorbed water played an important role in the catalytic conversion of CEES through hydrolysis to form hydroxyethyl ethyl sulfide (HEES). Basic environment provided by nitrogen and sulfur groups promoted this process. Among the modified textiles, C-Text-ON adsorbed CEES with a 23% increase compared to C-Text (238 mg/g), under humid conditions. Additionally, the presence of basic sites on the C-Text, C-Text-ON and C-Text-OS textiles stimulated the dehydrohalogenation of CEES, leading to the formation of ethyl vinyl sulfide (EVS). These results provide important insights into the interactions between CEES and water-exposed textiles, contributing to the design of more effective protective garments against chemical warfare agents.

Environmental Implication

The role of humidity is often overlooked in the detoxification studies of hazardous and toxic compounds, despite being an important parameter in realistic conditions. Using direct droplet contacts and vapors exposure, the main methods of contamination, it was shown that pre-adsorbed water did not significantly hinder the textiles’ capability to adsorb 2-choloroethyl sulfide, CEES (mustard gas surrogate). Contrary, it played a crucial role in catalyzing the decomposition of CEES into less toxic hydroxyethyl ethyl sulfide through hydrolysis. The results indicate the advantage of introducing basic functionalities through heteroatom-modification of nanoporous carbon textiles in warfighter protective garments in humid environments.