Photocatalytic degradation of bisphenol A by GO-TiO2 nanocomposite under ultraviolet light: synthesis, effect of parameters and mineralisation

Abstract

ABSTRACT In this study, titanium dioxide nanoparticles (TiO 2 ) were loaded on graphene oxide (GO) by hydrothermal method and used as a photocatalyst for the degradation of bisphenol A (BPA). The optimum photocatalytic conditions were evaluated by studying the effect of operating parameters such as initial pH, photocatalyst dosage, radiation intensity, and initial BPA concentration. Under optimal conditions, 88.9% BPA degradation and 65% BPA mineralisation were obtained after 60 min of UV radiation. The presence of anions such as chloride, nitrate, carbonate, and bicarbonate in the reaction reactor significantly reduced the degradation efficiency and the constant kinetic rate by producing reactive species with weaker oxidation potential. The kinetic rate emphasised that the integrated TiO2 and GO nanoparticles have a high degradation activity (0.31 min−1) in the presence of UV compared to the alone process of UV (0.003 min−1) and adsorption (0.007 min−1). The radical trapping experiments showed that h+, •OH, O2 •-, and e− are present in the reaction system, and the h+ and •OH species play a major role in the degradation process. The system energy consumption for different concentrations of BPA (10–100 mg/L) was in the range of 23.06–99.96 kWh/m3. The reusability results showed that the activity of GO-TiO2 in the degradation of BPA did not change significantly even after five cycles, which indicates its excellent photocatalytic stability. To evaluate the performance of GO-TiO2, the photocatalytic activation, oxidants such as H2O2, persulphate, and peroxymonosulfate were evaluated, and the results showed complete degradation of the contaminant at low concentrations of oxidants. The performance of the system for BPA removal in various real solutions such as drinking water, raw water, and treated wastewater was found to be 85.52, 79.52%, and 55.65%, respectively. Based on comparative experiments and trapping of reactive species, the photocatalytic degradation mechanism of BPA by GO-TiO2/UV was proposed.