Investigation of textural properties and photocatalytic activity of PbO/TiO2 and Sb2O3/TiO2 towards the photocatalytic degradation Benzophenone-3 UV filter

Benzophenone-3 (BP-3) is a widely used organic UV filter in sunscreen which has been detected in surface and groundwater. BP-3 can affect the aquatic environment and human health. In this study, PbO/TiO 2 and Sb 2 O 3 /TiO 2 photocatalyst were synthesized for the photocatalytic degradation of Benzophenone-3 (BP-3) and various degradation parameters such as initial pH value, initial concentration, and the dose of catalysts were optimized. Two different TiO 2 based catalysts PbO/TiO 2 and Sb 2 O 3 /TiO 2 were synthesized by hydrothermal method. Synthesized photocatalysts were characterized by X-ray diffraction pattern (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), BET and UV–Vis DRS techniques. Molar ratio variation of PbO and Sb 2 O 3 with respect to TiO 2 significantly affected the surface area, structure, and bandgap of photocatalyst and hence the variation in degradation efficiency of the photocatalyst was observed. The BP-3 can be completely degraded by using PbO/TiO 2 within 120 min under UV-C irradiation. The highest degradation of BP-3 was obtained for the 20 µM concentration at pH 7 when the dose was adjusted to be 0.75 g/L. However, negligible degradation of BP-3 was demonstrated in the absence of a catalyst. Moreover, with the catalysts PbO/TiO 2 and Sb 2 O 3 /TiO 2 , BP-3 followed the pseudo-first-order kinetics with a rate constant of 3.58 × 10 −2 min −1 and 0.92 × 10 −2 min −1 respectively. Electron paramagnetic resonance (EPR) spectrum with three distinct peaks with an intensity of 1:1:1 showed the presence of TEMP- 1 O 2 adduct which suggested the generation of 1 O 2 (singlet oxygen) in both catalysts. The plausible mechanism of BP-3 degradation was proposed by the Gas chromatography-mass spectrometry (GC-MS) analysis which showed the formation of pentamethyl- and 5-Hydroxy-7-methoxy-2-methyl-3-phenyl-4-chromenone byproducts on BP-3 photocatalytic degradation by the synthesized catalyst.