Ferrate(VI) Oxidation of Recalcitrant Compounds: Removal of Biological Resistant Organic Molecules by Ferrate(VI)

摘要

The oxidation of recalcitrant compounds, ethylenediamine-tetraacetate (EDTA) and sulfamethoxazole (SMX) by ferrate(VI) (Fe(VI), Fe~(VI)O_4~(2-)) is presented. Kinetics of the reactions were determined as a function of pH at 25 °C by a stopped-flow technique. The rate law for the oxidation of these compounds by Fe(VI) is first-order with respect to each reactant. The observed second-order rate constants for the reaction of Fe(VI) with SMX decreased non-linearly with increase in pH and are possibly related to protonations of Fe(VI) and compounds. The individual rate constants, k (M~(-1)'s~(-1)) of Fe(VI) species, HFeO_4~- and FeO_4~(2-) with protonated and deprotonated forms of compounds were estimated. The HFeO_4~-species reacts much faster with these compounds than does the FeO_4~(2-) species. The results showed that Fe(VI) has the potential to serve as an environmentally-friendly oxidant for removing biologically resistant organic molecules within minutes and converting them to relatively less toxic by-products in water.