Insight into the Role of Sulfur Confined within the Porous Carbon Structure in 2-Chloroethyl Ethyl Sulfide Adsorption

Abstract

The interactions of 2-chloroethyl ethyl sulfide (CEES), a mustard gas surrogate, with porous carbons, whose surface features were tuned by sulfur insertion, were investigated in this study. The modification process introduced 0%, 5%, 10%, and 50% sulfur relative to the total pore volume of each carbon. Both surface chemistry and porosity were affected, and the extent of changes depended on the initial carbon surface features. CEES adsorption experiments were performed in a closed system, enabling simultaneous analysis of the surrogate adsorbed on the carbon surface and its vapors released into the headspace. The results showed that a gradual decrease in the porosity by sulfur insertion markedly hindered CEES adsorption. The measurement of the heat released upon complete filling of the pores revealed its dependence on accessible pores with the highest adsorption potentials. The analysis of the efficiency of CEES extraction from the pore system combined with DFT calculations suggested that at a low sulfur loading (5% of pore volume), confined sulfur promoted the retention of CEES molecules due to Ssurface–SCEES dispersive interactions, emphasizing the importance of deposited sulfur for separation and extraction processes.