Preparation of Ag3PO4/CNH and the performance for photocatalytic degradation of microcystin-LR under visible light

Protonated g-C 3 N 4 (CNH) was prepared with g-C 3 N 4 powder by HNO 3 hydrothermal method, and Ag 3 PO 4 /CNH composite was further synthesized by chemical precipitation. The prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectra, UV–Vis diffuse reflectance spectrometer, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, photoluminescence spectra and electron spin resonance. The photocatalytic performance of Ag 3 PO 4 /CNH under visible light was evaluated by the microcystin-LR (MC-LR) degradation experiment. The results showed that Ag 3 PO 4 could be successfully loaded on the surface of CNH, and its light absorption intensity was significantly improved compared with CNH. When the mass ratio of Ag 3 PO 4 was 20% in Ag 3 PO 4 /CNH composite, the photodegradation efficiency of MC-LR was the highest under the condition of visible light irradiation for 2 h with the degradation rate of 79.8% which was 5.4 times higher than that of pure CNH and 9.8 times higher than that of pure g-C 3 N 4 . The photodegradation reaction of Ag 3 PO 4 /CNH for MC-LR was in line with quasi-first-order kinetic model. The scavenger tests proved that ·O 2 – and h + played the major role in the degradation process. A possible Z-scheme degradation mechanism of MC-LR over Ag 3 PO 4 /CNH hybrid was proposed.