Photocatalytic degradation of bisphenol-A under UV-LED, blacklight and solar irradiation

Abstract

This study aims at investigating the photocatalytic treatment of bisphenol-A (BPA) under various irradiation sources in order to identify cleaner and more sustainable technologies compared to conventional photocatalytic wastewater treatment systems. For this purpose, parallel experimental runs were carried out in two batch-operated slurry photoreactors under UVA irradiation provided by either a light-emitting diode (UV-LED) or a UV blacklight lamp (UV-BL), as well as in a solar compound parabolic collector (CPC) reactor under natural sunlight. The effect of key operating parameters, such as the initial BPA and TiO2 concentrations, water matrix, and treatment time, on the efficiency of the three photocatalytic systems was evaluated. The photocatalytic degradation of BPA was found to fit well with the pseudo-first-order kinetic model. BPA removal rate increased with catalyst concentration and with decreasing the initial concentration of BPA. The addition of humic acids was found to be inhibitory for all photocatalytic systems. At the best conditions assayed (C0 = 2.5 mg/L, TiO2 = 250 mg/L), BPA was completely degraded within 20, 30, and 120 min under UV-LED, solar, and UV-BL irradiation, respectively. The corresponding reaction rates were 0.230, 0.151, and 0.025 min−1, and TOC removal was 88, 67, and 33% after 90 min of treatment. In all cases, TiO2/UV-LED achieved the highest removal efficiency and it was found to be significantly more energy-efficient than the TiO2/UV-BL system. All in all, LED-driven photocatalysis was found to be advantageous over conventional TiO2/UV-BL systems in terms of performance and sustainability, and an appropriate alternative to solar photocatalysis in areas where sunlight is inadequate.