Photocatalytic performances of heterojunction catalysts of silver phosphate modified by PANI and Cr-doped SrTiO3 for organic pollutant removal from high salinity wastewater

In this work, Ag3PO4/PANI/Cr:SrTiO3 photocatalysts were designed to effectively eliminate organic pollutants including Rhodamine B and phenol from high salinity wastewater under visible light. The phase composition, optical properties, and morphology of powders were studied, and the effects of inorganic salts on removal performance of the as-prepared particles were also tested. Results showed that the photocatalytic activities of Ag3PO4/PANI/Cr:SrTiO3 composites for Rhodamine B and phenol reached 100% within 10 min and 18 min, respectively. The reaction rate of pure Ag3PO4 was 7 times less than that of the ternary composite with the adding of PANI and Cr:SrTiO3. The activity of Ag3PO4/PANI/Cr:SrTiO3 remained at 92.25% after five cycles, so the photocatalytic and recyclable performance of ternary composite was greatly improved. In addition, when there was SO42- with a content of ranging from 1% to 21%, the degradation activity of the ternary catalyst under visible light was not changed for Rhodamine B, which indicated that the ternary catalyst exhibited the excellent sulfate resistance ability. Results from ESR and radical trapping experiments showed that O2- and h+ made an important contribution to visible-light photocatalytic activities.