Degradation of bisphenol A by the UV and UV/H2O2 processes: Evaluation of process variables through experimental design

Abstract

AbstractUV‐based technologies have been proposed for the treatment of wastewater containing bisphenol A (BPA), a toxic, endocrine‐disruptor pollutant. Nevertheless, the evaluation of the role of process variables through experimental design has not been previously addressed. In this study, the effects of BPA and H2O2 initial concentrations, and specific photon emission rate (EP,0) on BPA degradation by the UV and UV/H2O2 processes were investigated, using the Doehlert design and response surface analysis. The experiments were performed in a tubular reactor equipped with a 254‐nm UV lamp, for [H2O2]0 and EP,0 in the ranges 1.6–9.6 mmol · L−1 and 0.87 × 1018–3.6 × 1018 photons · L−1 · s−1, respectively. Photolysis ([BPA]0 = 10–50 mg · L−1) was shown to be inefficient for BPA degradation and mineralization, with pollutant removals lower than 55 %. The specific BPA photolysis rate and BPA removal decreased with increasing [BPA]0. In contrast, all the UV/H2O2 experiments ([BPA]0 = 50 mg · L−1) resulted in total BPA degradation after 60 min of irradiation. In this case, the best conditions were [H2O2]0 = 7.6 mmol · L−1 and Ep,0 = 3.6 × 1018 photons · L−1 · s−1, achieving the highest BPA degradation rate and removal after 15 min, and the second highest TOC removal after 180 min. In most experiments less than 75 % TOC removal was achieved, with 95 % mineralization observed solely for the highest [H2O2]0 and EP,0. In any case, the residual toxicity and endocrine activity of treated solutions must be determined, in order to prove the applicability of the UV/H2O2 process for real water and wastewater treatment.