Enhanced Treatment of Municipal Wastewater Effluents by Fe-TAML/HO: Efficiency of Micropollutant Abatement.

Combining iron with a tetraamido-macrocyclic ligand (Fe-TAML) as a catalyst and with hydrogen peroxide (HO) as the bulk oxidant is a process that has been suggested for the oxidative abatement of micropollutants during water treatment. In this study, the reactivity of the Fe-TAML/HO system was evaluated by investigating the degradation of a group of electron-rich organic model compounds with different functional groups in a secondary wastewater effluent. Phenolic compounds and a polyaromatic ether are quickly and substantially abated by Fe-TAML/HO in a wastewater effluent. For tertiary amines, a moderate rate of abatement was observed. Primary and secondary amines, aromatic ethers, aromatic aldehydes, and olefins are oxidized too slowly in the investigated Fe-TAML/HO systems to be significantly abated in a secondary wastewater effluent. Trichlorophenol is readily oxidized to chloromaleic acid and chlorofumaric acid, which support a one-electron transfer reaction as the initial step of the reaction between Fe-TAML/HO and the target compound. Fe-TAML/HO does not oxidize bromide to hypobromous acid; however, iodide is oxidized to hypoiodous acid, and as a consequence, the HO consumption is accelerated by a catalytic reaction in iodide-containing water. Overall, Fe-TAML/HO is a rather selective oxidant, which makes it an interesting system for the abatement of electron-rich phenolic-type pollutants.