Oxidative degradation and mineralization of the endocrine disrupting chemical bisphenol-A by an eco-friendly system based on UV-solar/H2O2 with reduction of genotoxicity and cytotoxicity levels

Abstract

A solar-driven advanced oxidation process at a lab scale was studied for the degradation and mineralization of the known endocrine disrupting chemical (EDC), bisphenol A (BPA). Preliminary tests were performed varying the irradiation source, BPA/H2O2 ratio, temperature, initial H2O2 concentration, initial solution pH, and initial BPA concentration, then, the operational conditions of the UV-solar/H2O2 were optimized by a response surface methodology (RSM), providing the following responses: UV-solar/H2O2 process at pH 3.0, [BPA]0 = 25 mg L−1, [H2O2] = 350 mg L−1, T = 50 °C, achieving BPA degradation of 77.4% and BPA mineralization of 38.2%, H2O2 consumption of 230 mg L−1. From the optimized condition, different pH ranges were tested (3.0; 5.0; 7.0; 9.0; and 11.0), where, at solution pH 5.0 the best removal rates were achieved (89.2% BPA degradation and 49.0% BPA mineralization). The BPA amount in solution was monitored by High Performance Liquid Chromatography (HPLC) and a study of the intermediate reaction by-products was performed by Gas Chromatography–Mass Spectrometry (GC–MS) analyses, highlighting the lower amount of by-products identified when the solution pH 5.0 was employed, rather than the solution pH 3.0. Genotoxicity tests with Zebrafish (Danio rerio) and cytotoxicity tests with Allium cepa were performed aiming to evaluate errors in the cells and nuclear abnormalities of the tested organisms induced by BPA raw samples, as well as by the BPA samples treated by the UV-solar/H2O2 process. Therefore, the bio-toxicity levels for an animal and a vegetal bio-indicator were reduced by applying a renewable source of energy as the irradiation source for the UV/H2O2 process, representing an efficient and eco-friendly alternative for BPA treatment in aqueous solutions.