A self-gating proton-coupled electron transfer reduction of hexavalent chromium by core-shell SBA-Dithiocarbamate chitosan composite.

We have proposed a novel strategy for the reduction plus adsorption process for hexavalent chromium elimination by thiol functional hybrid materials through a self-gating process. Namely, we exploit that coating dithiocarbamate chitosan at the surface of SBA-15 affords a core-shell composite that undergoes reversible shape transformations while thiol functional groups acted as proton-coupled electron donor for [CrO]. The reduction of [CrO] to Cr was highly efficient and exceptionally rapid, occurred within 5 min with the reduction amount of 899.66 mg of [CrO] / 1 g of nanocomposite as a record high value. During the reduction of [CrO], thiol functional groups (-SH) were oxidized into disulfide linkages (SS), and simultaneously chitosan matrix turned into shrunken structure because of the consuming of protons, preventing any release of Cr. Disulfides can also be reversely reduced to thiols by thiosulphates (SO), which was attractive for regeneration and recyclability of the nanocomposite. Moreover, the [CrO] elimination through self-gating process was highly selective against a huge concentration of background electrolytes. This alternative strategy ensures the outstanding and stable performance in applied fields, and could be conducted in various pollution control techniques like permeable reactive barriers.