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Oxidation of manganese (II) with ferrate: Stoichiometry, kinetics, products and impact of organic carbon

TitleOxidation of manganese (II) with ferrate: Stoichiometry, kinetics, products and impact of organic carbon
Publication TypeJournal Article
Year of Publication2016
AuthorsGoodwill JE, Mai X, Jiang Y, Reckhow DA, Tobiason JE
JournalChemosphere
Volume159
Start Page457
Pagination457-464
Date Published06/2016
KeywordsAdvanced oxidation, Ferrate, Kinetics, Manganese, nanoparticles, Stoichiometry
Abstract

Manganese is a contaminant of concern for many drinking water utilities, and future regulation may be pending. An analysis of soluble manganese (Mn(II)) oxidation by ferrate (Fe(VI)) was executed at the bench-scale, in a laboratory matrix, both with and without the presence of natural organic matter (NOM) and at two different pH values, 6.2 and 7.5. In the matrix without NOM, the oxidation of Mn(II) by Fe(VI) followed a stoichiometry of 2 mol Fe(VI) to 3 mol Mn(II). The presence of NOM did not significantly affect the stoichiometry of the oxidation reaction, indicating relative selectivity of Fe(VI) for Mn(II). The size distribution of resulting particles included significant amounts of nanoparticles. Resulting manganese oxide particles were confirmed to be MnO2 via X-ray photoelectron spectroscopy. The rate of the Mn(II) oxidation reaction was fast relative to typical time scales in drinking water treatment, with an estimated second order rate constant of approximately 1 × 10(4) M(-1) s(-1) at pH 9.2 and > 9 × 10(4) M(-1) s(-1) at pH 6.2. In general, ferrate is a potential option for Mn(II) oxidation in water treatment.

DOI10.1016/j.chemosphere.2016.06.014