Oxidative treatment of bisphenol A by Fe(VI) and Fe(VI)/H2O2 and identification of the degradation products

Abstract

Bisphenol A (BPA) is classified as a xenoestrogen compound and has caused adverse effects in humans and animals. Ferrate(VI) (Fe(VI)) and the combination of Fe(VI) and hydrogen peroxide ( H 2 O 2 ) were investigated to degrade BPA in water. This study evaluated the impact of BPA initial concentration (50, 200, and 1, 000 μ g L −1 ) and background anions ( Cl − , PO 4 3 − , and NO 3 − ) on the degradation efficiency of the combined oxidants. The results showed that Fe(VI)/H 2 O 2 performed significantly better than Fe(VI) or H 2 O 2 alone. BPA degradation ( 50 μ g L −1 ) using Fe(VI)/H 2 O 2 was recorded at 99.8% within 60 min at pH 8.0 with [Fe(VI)]/[H 2 O 2 ] molar concentration ratio of 250:2,500. At the same initial concentration of BPA and pH condition, the degradation of BPA using Fe(VI) and H 2 O 2 was recorded as 89% ([Fe(VI)]/[BPA]=5) and 33.5% ([H 2 O 2 ]=2, 500 μ g L −1 ), respectively. BPA degradation using Fe(VI)/H 2 O 2 was 99.8%, 85.3%, and 43.8% for an initial concentration of 50, 200, and 1, 000 μ g L −1 , respectively. The presence of Cl − and NO 3 − ions had no obvious effects on BPA degradation; however, a considerable reduction in the degradation efficiency was observed for PO 4 3 − ( 350 μ g L −1 ) due to the complexation between PO 4 3 − ion and ferric oxy/hydroxides. There were eleven intermediates detected in BPA degradation using Fe(VI)/H 2 O 2 , and three degradation pathways were proposed, including hydroxylation, cleavage of the C-C bond, and oxidation to form ring opening products. A reduction in ecotoxicity was observed after 60 min of reaction for both Fe(VI) and Fe(VI)/H 2 O 2 . • Bisphenol A (BPA) degradation using Ferrate(VI) (Fe(VI)) and Fe(VI)/H 2 O 2 was studied. • Nearly a complete degradation of BPA in water was achieved with Fe(VI)/H 2 O 2 . • BPA degradation by Fe(VI)/H 2 O 2 was affected by PO 4 3 − , but not by Cl − and NO 3 − . • Eleven intermediates in the BPA degradation were detected. • BPA degradation pathways during the oxidative treatments were proposed.