Elimination of Organic Contaminants during Oxidative Water Treatment with Ferrate(VI): Reaction Kinetics and Transformation Products

Abstract

Ferrate(VI) can be used to oxidize various trace organic contaminants (TrOCs) in municipal water and wastewater treatments. The efficiency of ferrate(VI) oxidation for TrOC elimination depends on the reactivity of ferrate(VI) with a target TrOC and the dosage and stability of ferrate(VI) in a given water matrix. This article reviews recent advances in predicting TrOC elimination during water treatment with ferrate(VI) with a focus on the principle-based approaches for modeling the reaction kinetics of ferrate(VI) and transformation products and pathways of TrOCs. Using the chemical kinetics based on second-order rate constants of ferrate(VI) (kFe(VI)) and ferrate(VI) exposures, predictions of the elimination efficiency of various TrOCs can be made as a function of ferrate(VI) doses. The kFe(VI) with simple organic compounds with electron-rich moieties (ERMs) have been determined which also serves as a basis to predict the kFe(VI) for TrOCs with more complex structures based on semi-empirical QSAR correlations. The ferrate(VI) exposure as a function of ferrate(VI) doses can be estimated based on the self-decay kinetics of ferrate(VI). Transformation products of ferrate(VI) oxidation have been identified/quantified for simple organic compounds and TrOCs with ERMs, which have been used to propose ferrate(VI) reaction mechanisms for each ERM. More product studies are required to build concrete reaction rules for predicting transformation pathways of TrOCs during ferrate(VI) oxidation. © 2016 American Chemical Society.