Simultaneous photocatalytic Cr(VI) reduction and 2,4,6-TCP oxidation over g-C3N4 under visible light irradiation

In this study, a rapid reduction of Cr(VI) and degradation of 2,4,6-trichlorophenol (2,4,6-TCP) in a simultaneous manner was reported through the catalysis of g-C3N4 under visible light (lambda > 420 nm) irradiation. The effects of initial concentration of reactants, dissolved O-2 and pH value were investigated systematically. It indicated that, under the optimized concentration, the Cr(VI) reduction and 2,4,6-TCP oxidation could be accomplished in couple of hours in the presence of g-C3N4. And also, the O-2 involvement and low pH value were able to significantly improve the removal rate of Cr(VI) and 2,4,6-TCP. In addition, the reaction mechanism was investigated through monitoring the reduced states of Cr(VI) and active oxygen intermediates formed during photoreaction by ESR and XPS, as well as determining the degradation products of 2,4,6-TCP by HPLC-MS. The results supported that the redox reactions of Cr(VI) and 2,4,6-TCP can be performed simultaneously via a synergistic oxidation-reduction mechanism in the presence of g-C3N4 under visible light irradiation. (C) 2013 Elsevier B.V. All rights reserved.