Efficient degradation of organic pollutants with a sewage sludge support and in situ doped TiO2 under visible light irradiation conditions

摘要

TiO2 is considered to be the most promising candidate for photocatalytic organic pollutant degradation, however, it suffers from a large band gap, which means that it is active only in the UV region. Thus, in recent decades, a considerable amount of research has investigated how to expand the optical absorption spectrum of TiO2 into the visible region. In this study, we developed a new approach that used sewage sludge as the support and dopant to construct a bimodal-pore composite visible-light-driven TiO2 photocatalyst (SS-Ti-700). The design was based on a mesoporous assembly of the organic and inorganic compounds in the sewage sludge, which served as the scaffold templates; a SiO2-TiO2 nanostructure, which has been demonstrated to have markedly high photocatalytic activity; and the in situ doping of TiO2 with transition metals (Fe, Cu, and Cr) originating from the sewage sludge, which significantly enhances visible-light absorption. Kinetic analysis showed that this arrangement exhibited rapid p-nitrophenol degradation and mineralization under visible light irradiation conditions. The possible reaction mechanism was explored by ESR spectroscopy. Our protocol demonstrates a new approach for the potential environmentally benign reuse of sewage sludge and provides a facile, cost-effective, and eco-friendly approach for synthesizing TiO2-based mesoporous photocatalysts.