Enhanced degradation of mustard gas surrogate on copper hydroxyl nitrate-functionalized carbon textiles: Analyzing...

To enhance surface reactivity and promote the adsorption and degradation of 2-chloroethyl ethyl sulfide (CEES), composites containing copper hydroxyl nitrate (CuON) deposited on initial carbon textile (FM) as well as O-, N- and S-modified carbon textiles (FM-ONS) were developed and referred to as FM-CuON and FM-ONS-CuON, respectively. Detoxification of CEES was evaluated either in a vapor or liquid phase. The textiles' vapor adsorption capacity reached 464 mg/g, with removal governed by porosity and surface chemistry. All treated textiles exhibited strong liquid CEES adsorption and effective volatilization suppression, with less than 0.1 % of CEES in the headspace after 3 h of exposure. The analysis of extracts indicated dehydrohalogenation as dominant detoxification pathway on all samples, producing less toxic ethyl vinyl sulfide (EVS). Its amount formed on FM-CuON and FM-ONS-CuON, increased 1.5 and 3.3 times compared to those on their copper-free counterparts, respectively. The CuON deposition enhanced the activity of dehydrohalogenation by introducing Lewis acidic Cu(II) centers, with oxygen in the nitrate structure acting as a Lewis base. Moreover, on FM-ONS-CuON, a synergistic effect of support chemistry and CuON led to the highest CEES adsorption/conversion and largest increase in the EVS amount, in spite of a small amount of deposited CuON. This superior activity was attributed to: (1) Heteroatom-containing basic sites capable of accepting protons released during an elimination reaction; (2) Cu(II) Lewis-acidic centers that facilitated a CCl bond cleavage, and (3) oxygen in nitrate acting as Lewis-basic sites that abstract a labile hydrogen from a cyclic cation intermediate.