Photocatalytic degradation of bisphenol A in the presence of Ce–ZnO: Evolution of kinetics, toxicity and photodegradation mechanism

• Influence of different parameters on the degradation and mineralization of BPA.
• Identification of possible degradation products.
• Toxicity tests conducted with Vibrio fischeri.
• Simple and direct photodegradation mechanism of BPA is proposed.

Ce–ZnO (2 mol %) and undoped ZnO catalysts have been synthesized through hydrothermal method and characterized by X-ray diffraction (XRD), Nitrogen physisorption at 77 K; Fourier transformed infrared spectroscopy (FTIR), UV–Visible spectroscopy, Photoluminescence spectra (PL), and Raman spectroscopy. Ce-doping reduces the average crystallite size, increases the BET surface area, shifts the absorption edge, reduces the electron–hole recombination and consequently improves photodegradation efficiency of Bisphenol A (BPA) in the presence of UV irradiation and hydrogen peroxide. The photocatalytic optimum conditions were established by studying the influence of various operational parameters including catalyst concentration, initial BPA concentration, H2O2 concentration and initial pH. Under optimum conditions, Ce–ZnO (2%) achieved 100% BPA degradation and 61% BPA mineralization after 24 h of UV irradiation. BPA degradation reaction followed pseudo first-order kinetics according to the Langmuir–Hinshelwood model. Based on the identified intermediate products, the possible mechanism for BPA photodegradation is proposed. Toxicity under the optimum condition was also evaluated.

Proposed photocatalytic degradation pathway of BPA in the presence of Ce– ZnO (2%)/UV/H2O2 system.Figure optionsDownload as PowerPoint slide