Reactive adsorption of CEES on iron oxyhydroxide/(N-)graphite oxide composites under visible light exposure

Abstract

The interactions of 2-chloroethyl ethyl sulfide (CEES) with the surface of iron oxyhydroxide and its composites with graphite oxide and/or aminated graphite oxide were studied under visible light irradiation. Materials exposed to CEES were extensively characterized by FTIR-STR, UV-VIS-NIR, and TA-MS. The gaseous/vaporous reaction products were identified by GC-MS. The compounds deposited on the surface of the materials were analyzed in acetonitrile extracts by NMR and MS-MS. The FTIR results indicated the existence of alcohol groups on the surface of the exhausted samples and the involvement of OH groups in the CEES reactive adsorption. Ethyl vinyl sulfide (EVS) was the only volatile compound detected as a result of the reaction with the surface. Two adsorption sites for either CEES or EVS were identified on the adsorbent surfaces. As a result of CEES reactive adsorption Fe(III) was reduced, which indicates its crucial role in the oxidation of CEES and EVS. On the composites, the detection of disulfides as products of advanced oxidation of CEES suggests the activation of thiyl and oxygen radicals. This indicates that the incorporation of GO and GOU into iron oxyhydroxides strongly increases the oxidation potential of oxyhydroxides and induces the formation of radicals. The main promoters of CEES transformation are proposed to be OH groups and thiyl radicals.