Synthesis of visible-light-driven photocatalyst of TiO2 modified waste red mud and its application in tetracycline hydrochloride removal

Solid waste red mud (RM) was used as a raw material to obtain a composite of TiO2/RM in a green and feasible method, and the prepared catalysts exhibited excellent performance in removing tetracycline hydrochloride (TC) under visible light. The results showed that after the modification of TiO2 on the surface of RM, the catalyst still preserved a narrow band gap similar to that of RM; the photocurrent response of the prepared catalysts was significantly improved. In the photodegradation of TC, because of the lower electron transfer resistance and the promoted carrier separation, TiO2/RM showed much better performance than RM or TiO2. The catalysts also exhibited high anti-interference ability and long-term stability in the photocatalysis process. The possible catalytic mechanism of the prepared catalysts under visible light and the TC degradation pathways are presented. Toxicity assessment by cyanobacteria certified that the toxicity of TC was greatly weakened. These results demonstrate that hazardous industrial waste RM, globally produced in large amounts, could be effectively utilized in producing environmentally friendly catalysts for removing organic pollutants by using visible light.