Preparation of phosphotungstic acid/SiC and their photocatalytic activity for rhodamine B

Abstract

Four kinds of x wt.% phosphotungstic acid/silicon carbide (PTA/SiC) photocatalysts were prepared by impregnation method with SiC, 12-phosphotungstic acid (PTA) as raw materials. The structure of samples was characterised by X-ray diffraction, ultraviolet–visible diffuse reflectance spectra, scanning electron microscope. The photocatalytic activity of samples was evaluated by the degradation of rhodamine B (RhB) under a xenon lamp (λ≥420 nm). The results indicate that the photocatalysts not only maintained the SiC structure but also kept the Keggin structure of PTA. The 20 wt.% PTA/SiC exhibited the best photocatalytic degradation efficiency reaching up to 77% for 180 min irradiation, and the photo-degradation rate constant was determined to be 7.82 × 10−3 min−1. In the presence of H2O2, the photocatalytic degradation rate of 20 wt.% PTA/SiC composites was increased to 87%, and the photodegradation reaction rate constant was 7.77 × 10−3 min−1. According to free radical trapping experiments, it is proved that hydroxyl radical (·OH) plays an important role in photocatalysis.