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

Abstract

Abstract UV‐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 H 2 O 2 initial concentrations, and specific photon emission rate ( E P,0 ) on BPA degradation by the UV and UV/H 2 O 2 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 [H 2 O 2 ] 0 and E P,0 in the ranges 1.6–9.6 mmol · L −1 and 0.87 × 10 18 –3.6 × 10 18 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/H 2 O 2 experiments ([BPA] 0 = 50 mg · L −1 ) resulted in total BPA degradation after 60 min of irradiation. In this case, the best conditions were [H 2 O 2 ] 0 = 7.6 mmol · L −1 and E p,0 = 3.6 × 10 18 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 [H 2 O 2 ] 0 and E P,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/H 2 O 2 process for real water and wastewater treatment.