Ferrate(VI)-peracetic acid oxidation process: Rapid degradation of pharmaceuticals in water

This paper presents, for the first time, an oxidation process of ferrate(VI) (Fe(VI), FeO42-)-peracetic acid (CH3C(O)OOH, PAA) to rapidly degrade micropollutants in water. The effect of concentrations of Fe(VI) and PAA showed that complete removal (degradation below detection limit) of a pharmaceutical, carbamazepine (CBZ, 10.0 µM), could be achieved in 60 s at a molar ratio of Fe(VI) to CBZ of 20.0 and 100.0 µM PAA under mild alkaline condition (pH 9.0). The results of the experiments performed in the presence of quenching agents, i.e., tert-butyl alcohol and 2,4-hexadiene, suggested that the iron-based reactive species (Fe(V)/Fe(IV)) and/or acetylperoxyl radicals (CH3C(O)OO●/CH3C(O)O●) were most likely responsible for the rapid oxidation of CBZ, rather than the hydroxyl radical (●OH). The major role of Fe(V)/Fe(IV) was supported by the high mass balance between loss of PMSO and formation of PMSO2 (>90%) during the oxidation of PMSO by Fe(VI)-PAA, which was not observed in the absence of iron species, i.e., PAA-Co(II)-PMSO system having acetylperoxyl radicals as reactive species. Significantly, the Fe(VI)-PAA oxidation process could degrade several other pharmaceuticals (i.e., sulfamethoxazole, sulfadimethoxine, trimethoprim, atenolol, propranolol, and caffeine) within 60 s, indicating its great potential in eliminating pollutants of emerging concern from water.