Critical role of oxygen for rapid degradation of organic contaminants in permanganate/bisulfite process.

Organic contaminants can be oxidized rapidly in permanganate/bisulfite (PM/BS) process due to generation of Mn(III) aq . However, the influence of O 2 and its role in contaminants degradation in PM/BS process are poorly understood. Thus, the influence of O 2 concentration on phenol removal was quantified and isotopic oxygen tracers ( 18 O-labeled water and 18 O 2 ) were employed to further unravel the mechanisms of PM/BS process. The introduction of O 2 to PM/BS process appreciably improved phenol oxidation. Under oxic conditions the oxidation products of bisulfite included SO 4 2− and HSO 5 − while SO 4 2− was the single stable oxidation product under anaerobic conditions. The oxygen isotope labeling experiments confirmed that HSO 5 − originated from the oxidation of SO 3 − by O 2 to SO 5 − and the following reduction of SO 5 − by HSO 3 − . Incorporation of oxygen isotope from H 2 18 O to MnO 2 due to the disproportionation of Mn(III) aq was observed, which verified the generation of Mn(III) aq in PM/BS process. The critical influence of O 2 on PM/BS process was mainly associated with rapid oxidation of SO 3 − by O 2 to SO 5 − , which otherwise competed with target contaminants for Mn(III) aq . Oxygen from H 2 O and/or O 2 can also be incorporated in the degradation products of organics in PM/BS process. [ABSTRACT FROM AUTHOR]