Novel methods of sewage sludge utilization for photocatalytic degradation of tetracycline-containing wastewater

Two types of novel municipal sewage sludge (SS) combined TiO2 photocatalysts (ST1 and ST2) were synthesized through calcination treatment under different atmospheres (air and N-2). The morphology, structure, and chemical states of photocatalysts were characterized by SEM, XRD, EDS, FT-IR, Raman UV-Vis, BET, and TG-IR. The results showed that ST2 consisted of a mesoporous graphene-like structure (20.02 nm) displayed exhibited better visible light photocatalytic performances and the highest BET surface area and pore volume (92.97 m(2) g(-1) and 0.46 cm(3)/g). The doping of Carbon and transition metals (Al, Mg) in TiO2 strengthened visible-light response by lowering the band gap. The photocatalytic ability is evaluated in the degradation of tetracycline, which is a typical antibiotic in the aquatic environment. The ST2 photocatalytic efficiency under visible light than that of ST1 and TiO2. The enhancement is formed together by porous surface and lower band gap of ST2, which could offer more active sites and facilitate faster electron-hole pair separation. In addition, the sludge-TiO2 calcination in N-2 (ST2) has the potential to reduce CO2 emission while recovering more energy from the sludge, which turned out to be a more cost-effective way to reutilization of sewage sludge compared with that of calcination in air.