Photochemical. oxidation mechanism of microcystin-RR by p-n heterojunction Ag/Ag2O-BiVO4

Microcystin-RR (MC-RR), a form of microcystin with two arginine moieties, is a cyanobacterial toxin that has been detected across a wide geographic range. It is a great concern globally because of its potential liver toxicity. Herein, the abilities of BiVO4, Ag-BiVO4, Ag2O-BiVO(4)and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation (lambda >= 420 nm) were investigated and compared. The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry. The results showed that the presence of Ag-0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag-0 at the p-n heterojunction. Moreover, the presence of Ag also greatly promoted the adsorption of MC-RR on the photocatalyst surface. Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.