Dehydrochlorination of adsorbed 1,1,2,2-tetrachloroethane on graphene oxide-based materials' surface: Comparison with dissolved form in aqueous environment.

Dehydrochlorination of 1,1,2,2-tetrachloroethane (TeCA) in graphene oxide (GO)-based materials-water two-phase system can be enhanced strongly. However, the dehydrochlorination kinetic of adsorbed TeCA on GO-based materials' surface is still unclear. Thus, in this study the dehydrochlorination kinetics of adsorbed TeCA on GO based-materials' surface was compared to the kinetics of dissolved TeCA in aqueous solution. The results showed that the dehydrochlorination kinetic constants of adsorbed TeCA on GO-based materials' surface (ks_F) were much greater than those of dissolved TeCA in aqueous solution (ka) due to the deprotonated surface oxygen-containing functional groups (e.g. COO-, and O-) served as conjugated bases to catalyze the reaction. In particular, at pH 8.0 and 9.0, the ks_F values for GO (20mg/L) were approximately 3 orders magnitude greater than ka values. Furthermore, the ks_F values of adsorbed TeCA for the low concentration of GO (20mg/L) were always greater than that for the high concentration of GO (100mg/L). The primary mechanism was that GO was apt to aggregate at high concentration, which enhanced the steric hindrance between O-containing functional groups and TeCA molecular. Consequently, the interfacial effects of GO-based materials at their low concentration could strongly enhance the transformation of adsorbed TeCA in aqueous environment.