Pathways of photocatalytic gas phase destruction of HD simulant 2-chloroethyl ethyl sulfide

摘要

Photocatalytic oxidation of HD simulant,2-chloroethyl ethyl sulfide (CEES),was studied in a specially designed coil and flow photocatalytic reactor by means of GC-MS and FTIR techniques.TiO_2 Hombikat UV 100 photocatalyst was deactivated after a few hours of operation,which was signaled by the appearance of incomplete oxidation products in the reactor effluent and accumulation of incomplete oxidation products on the TiO_2 surface.Complete reactivation of the photocatalyst was achieved by washing the photocatalyst with water.Compared to diethyl sulfide,CEES showed lower reactivity in photocatalytic oxidation and was accumulated on the TiO_2 surface after catalyst deactivation.Without UV irradiation,hydrolysis of CEES proceeded on the TiO_2 surface.Major gaseous products of CEES incomplete photocatalytic oxidation are acetaldehyde,chloroacetaldehyde,SO_2,diethyl disulfide,and chloroethylene.Surface products extracted from the TiO_2 surface with acetonitrile and water include mainly 2-chloroethyl ethyl sulfoxide and ethanesulfinic and ethanesulfornic acids,as well as diethyl di-,tri-,and tetrasulfides mono and disubstituted in the beta position with a chlorine or hydroxyl group.While surface monodentate sulfates can be removed upon washing,surface bidentate species stayed on the surface and possibly contribute to the permanent catalyst deactivation.