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

Abstract

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/TiO2 and Sb2O3/TiO2 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 TiO2 based catalysts PbO/TiO2 and Sb2O3/TiO2 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 Sb2O3 with respect to TiO2 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/TiO2 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/TiO2 and Sb2O3/TiO2, 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-1O2 adduct which suggested the generation of 1O2 (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.