Removal of microcystins (-LR, -YR, -RR) by highly efficient photocatalyst Ag/Ag3PO4 under simulated solar light condition

• Ag/Ag3PO4 catalyst was much more efficient than Ag3PO4 in degrading MC-LR.
• The activity of Ag/Ag3PO4 relied on particle morphology and Ag NPs content.
• MC-LR, -YR and -RR performed differently to the attack of Ag/Ag3PO4 catalyst.
• The stability of Ag/Ag3PO4 in removing MC-LR relied on the content of doped Ag.

Microcystins, which are a group of hepatotoxins, have stable physicochemical properties. Photocatalysis has been proven to be effective for removing refractory organics. In this study, a novel visible light-sensitive photocatalyst (Ag/Ag3PO4), prepared by a simple irradiation method was used to treat microcystins (MC-LR, -YR, -RR). Results indicated that MC-LR was more easily degraded by Ag/Ag3PO4 catalysts than by Ag3PO4 alone, which was attributed to the change of Ag3PO4 morphology and the deposition of Ag nanoparticles (NPs) on Ag3PO4 after irradiation treatment. The photocatalytic efficiency of Ag/Ag3PO4 was found to be affected by both catalyst dosage and light intensity. The oxidation of the microcystins over this heterojunction catalyst reacted differently, with the removal efficiency following the trend: MC-YR > MC-RR > MC-LR. It is also worth noticing that the ratio of Ag NPs to Ag3PO4 for the best photocatalytic activity of the Ag/Ag3PO4 heterojunction in degrading MC-LR was not the one for the most stable state of it.