Modeling the Kinetics of Contaminants Oxidation and the Generation of Manganese(III) in the Permanganate/Bisulfite Process

Permanganate can be activated by bisulfite to generate soluble Mn­(III) (noncomplexed with ligands other than H2O and OH–) which oxidizes organic contaminants at extraordinarily high rates. However, the generation of Mn­(III) in the permanganate/bisulfite (PM/BS) process and the reactivity of Mn­(III) toward emerging contaminants have never been quantified. In this work, Mn­(III) generated in the PM/BS process was shown to absorb at 230–290 nm for the first time and disproportionated more easily at higher pH, and thus, the utilization rate of Mn­(III) for decomposing organic contaminant was low under alkaline conditions. A Mn­(III) generation and utilization model was developed to get the second-order reaction rate parameters of benzene oxidation by soluble Mn­(III), and then, benzene was chosen as the reference probe to build a competition kinetics method, which was employed to obtain the second-order rate constants of organic contaminants oxidation by soluble Mn­(III). The results revealed that the second-order rate constants of aniline and bisphenol A oxidation by soluble Mn­(III) were in the range of 105–106 M–1 s–1. With the presence of soluble Mn­(III) at micromolar concentration, contaminants could be oxidized with the observed rates several orders of magnitude higher than those by common oxidation processes, implying the great potential application of the PM/BS process in water and wastewater treatment.