Study on preparation, photocatalytic performance and degradation mechanism of Bi2WO6/Bi2S3/g-C3N4 composite

A new lotus-like Bi 2 WO 6 /Bi 2 S 3 /g-C 3 N 4 composite was synthesized through hydrothermal reaction and physical doping techniques. And the degradation of norfloxacin (NFX) using Bi 2 WO 6 /Bi 2 S 3 /g-C 3 N 4 (BiSW-GCN) photocatalytic material was investigated. Scanning electron microscopy (SEM) revealed that spherical Bi 2 S 3 and flake-like g-C 3 N 4 were closely adhered to the petals of Bi 2 WO 6 , with a uniform distribution of various elements observed in the Raman spectra. These spectra also indicated a reduction in fluorescence intensity and the recombination rate of photogenerated electron-hole pairs. Through analysis of the degradation efficiency of NFX with varying ratios of the photocatalytic materials, it was determined that the optimal photocatalytic performance was achieved when Bi 2 S 3 constituted 3 % of the Bi 2 WO 6 content, and the Bi 2 WO 6 /Bi 2 S 3 to g-C 3 N 4 ratio was set at 20:1. The influence of pH value, photocatalyst concentration, and NFX concentration on the degradation rate within the reaction environment was examined. Results showed that the material exhibited its highest efficiency in a neutral environment. With the addition of 1 g/L BiSW-GCN, the degradation rate of an 8 mg/L NFX solution reached 92.4 % within 120 min, and the total organic carbon (TOC) removal rate achieved 41.1 %. The kinetic constant for BiSW-GCN was calculated to be 0.0206 min −1 . A trapping experiment demonstrated that the primary toxicity of the photocatalytic process was due to hole action, followed by photoelectron generation. Based on the inhibitory effect of NFX on E. coli , the toxicity of the degraded NFX solution was found to be absent when analyzed using the product intermediate toxicity assessment method, thus confirming the potential for the by-product to be non-toxic.