Carbon-doped titania-polymethylsilsesquioxane aerogels for the photocatalytic degradation of antibiotics

Removal of antibiotics detected in wastewater or natural aquatic systems by regular municipal treatment is challenging. Photocatalysis is considered to be the most well-known and green strategy for such removal. However, the catalytic efficiency is restricted by UV radiation dependence, fast electron-hole recombination, and low porosity/surface area of the photocatalyst. In this study, we have developed a highly porous anatase TiO2-polymethylsilsesquioxane (PMSQ) aerogel with nonmetal carbon dopant, which can simultaneously enhance the adsorption ability and visible light photo-activity. And tetracycline hydrochloride (TCH) was selected as a model antibiotic. A high surface area (747 g cm−3) C-TiO2-PMSQ aerogel can remove 91% TCH within 180 min under visible light. But the removal needs to be in an isopropyl alcohol/water co-solvent, due to the intrinsic hydrophobicity of PMSQ. After a heat treatment under 400°C, the surface area of C-TiO2-PMSQ aerogel decreases to 618 g cm−3, and the sample loses its hydrophobicity, the removal of TCH can be in aqueous condition and the efficiency increases to 98%. Moreover, both catalysts can be recycled 7 times and still maintain high removal efficiency (85 and 64% remained for hydrophobic and hydrophilic gels, respectively).