Efficient degradation of pharmaceutical micropollutants in water and wastewater by FeIII-NTA-catalyzed neutral photo-Fenton process

Ferric-nitrilotriacetate complex (Fe III -NTA) has been adopted to catalyze the photo-Fenton degradation of emerging pharmaceutical micropollutants in water and wastewater at neutral pH. The generation of hydroxyl radicals (HO ) in UVA/Fe III -NTA/H 2 O 2 was identified by using electron spin resonance (ESR) trapping technique. The effects of critical parameters (e.g., NTA:Fe III molar ratio, Fe III -NTA and H 2 O 2 dosages) on the steady-state HO concentrations were studied in terms of the degradation of carbamazepine (CBZ, as a model compound) in Milli-Q water. In addition, the degradation of pharmaceuticals mixtures (including CBZ, crotamiton (CRMT) and ibuprofen (IBP)) in wastewater effluents from a biological aerated filter (BAF) by UVA/Fe III -NTA/H 2 O 2 was studied in continuous-flow mode. The results showed that the efficacies of Fe III -NTA in catalyzing photo-Fenton degradation of pharmaceuticals in wastewater effluents were comparable to those obtained by Fe III -ethylenediamine-N,N′-disuccinic acid (Fe III -EDDS), and far exceeded other Fe III -L complex (e.g., citric acid , malonic acid, oxalic acid and tartaric acid). More than 92% degradation efficiencies of CBZ, CRMT and IBP were obtained in continuous-flow mode under the given conditions of 0.178 mM Fe III -NTA (1:1), 4.54 mM H 2 O 2 , UVA intensity 4.05 mW cm −2 , hydraulic retention time (HRT) 2 h, influent pH 7.6 (±0.2) and temperature 20 °C. The results presented herein suggest that Fe III -NTA-catalyzed neutral photo-Fenton reaction can be an alternative tertiary process for the treatment of pharmaceutical micropollutants in secondary wastewater effluents.