Effect of Metal Ions on Oxidation of Micropollutants by Ferrate(VI): Enhancing Role of FeIV Species
journal contributionposted on 16.12.2020, 19:09 by Xianbing Zhang, Mingbao Feng, Cong Luo, Nasri Nesnas, Ching-Hua Huang, Virender K. Sharma
This paper investigated the oxidation of recalcitrant micropollutants [i.e., atenolol (ATL), flumequine, aspartame, and diatrizoic acid] by combining ferrate(VI) (FeVIO42–, FeVI) with a series of metal ions [i.e., Fe(III), Ca(II), Al(III), Sc(III), Co(II), and Ni(II)]. An addition of Fe(III) to FeVI enhanced the oxidation of micropollutants compared solely to FeVI. The enhanced oxidation of studied micropollutants increased with increasing [Fe(III)]/[FeVI] to 2.0. The complete conversion of phenyl methyl sulfoxide (PMSO), as a probe agent, to phenyl methyl sulfone (PMSO2) by the FeVI–Fe(III) system suggested that the highly reactive intermediate FeIV/FeV species causes the increased oxidation of all four micropollutants. A kinetic modeling of the oxidation of ATL demonstrated that the major species causing the increase in ATL removal was FeIV, which had an estimated rate constant as (6.3 ± 0.2) × 104 M–1 s–1, much higher than that of FeVI [(5.0 ± 0.4) × 10–1 M–1 s–1]. Mechanisms of the formed oxidation products of ATL by FeIV, which included aromatic and/or benzylic oxidation, are delineated. The presence of natural organic matter significantly inhibited the removal of four pollutants by the FeVI–Fe(III) system. The enhanced effect of the FeVI–Fe(III) system was also seen in the oxidation of the micropollutants in river water and lake water.