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

Protonated g-C3N4 (CNH) was prepared with g-C3N4 powder by HNO3 hydrothermal method, and Ag3PO4/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 Ag3PO4/CNH under visible light was evaluated by the microcystin-LR (MC-LR) degradation experiment. The results showed that Ag3PO4 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 Ag3PO4 was 20% in Ag3PO4/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-C3N4. The photodegradation reaction of Ag3PO4/CNH for MC-LR was in line with quasi-first-order kinetic model. The scavenger tests proved that center dot O-2(-) and h(+) played the major role in the degradation process. A possible Z-scheme degradation mechanism of MC-LR over Ag3PO4/CNH hybrid was proposed.