High efficiency degradation of tetracycline antibiotic with TiO2 - SiO2 photocatalyst under low power of simulated solar light irradiation

Abstract

Photocatalytic materials of TiO2/SiO2 (TS) was successfully synthesized by sol–gel method followed by calcination at 450-750 °C. The synthesized photocatalysts were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-Ray Spectroscopy (EDS), and UV-Vis diffuse reflectance spectra (DRS). In the research, 10 ppm tetracycline (TC) solution was used as a model antibiotic compound to evaluate the photocatalytic activity of the TiO2/SiO2 photocatalyst. The photocatalytic activity of the TiO2/SiO2 was evaluated in batch reactor under various conditions such as Ti: Si molar ratios, calcined temperatures under simulated solar light by using a 26 W ReptiGlo 2.0 compact lamp. The results showed that all synthesized samples are pure anatase phase with high crystallinity and high photocatalytic activities. Especially, the 500 °C calcined sample TiO2/SiO2 with molar ratio of TiO2:SiO2 to be 85:15 (TS15) exhibited the highest photocatalytic activity in TC degradation at catalyst dose of 0.10 g/L, reaching 84.49 % after 5 h irradiation which is higher than that of the TS25 sample (45.22 %) and the TS5 sample (57.52 %). Moreover, 4wt % of silver-doped TS15 photocatalyst responded the visible light in TC degradation up to 94.24 %. The photodegradation of TC over A4TS15 monolithic catalyst displayed a promising catalyst with interesting photodegradation yield of 85.73 % after 5 h irradiation and hardly any observable loss after seventh cycles. The Ag-doped TiO2/SiO2 photocatalyst could be a promising photocatalyst for removal and degradation of organic pollutants.