Treatability of five micro-pollutants using modified Fenton reaction catalysed by zero-valent iron powder (Fe(0))

Diuron, gabapentin, sulfamethoxazole, terbutryn and terbuthylazine are emerging micro-pollutants with concentrations in water and wastewater ranging from tens of ng/L to >10 μg/L levels. The Fenton oxidation catalysed either by zero-valent iron (Fe(0)) or by Fe(II) salts was studied to treat the targeted micro-pollutants and their mixtures at compound concentrations between 1 and 1000 µg/L. The Fe(0)-catalytic Fenton oxidation exhibited complete degradation of all micro-pollutants at initial solution pH 3 but at pH 5, the degradation was 90% for diuron, 80% for gabapentin, 95% for sulfamethoxazole, 100% for terbutryn and 70% for terbuthylazine, respectively. Moreover, dissolved organic carbon in multiple micro-pollutant solutions can be reduced by 70% at pH 3 and 46% at pH 5, which were much better than Fe(II)-catalytic Fenton reaction for the same pH conditions. SEM/EDX analysis showed the corrosion of iron surface and FTIR analysis evidenced the adsorption of oxidation by-products onto solid iron surface. Additionally, the toxicity of effluent after the treatment was reduced to minimal and the Behnajady-Modirshahla-Ghanbery (BMG) model fitted well to the kinetics of the mineralisation of the studied micropollutants. Finally, Fe(0) catalyst can be reused up to three times and the process produced no or less sludge at pH 3 and pH 5, respectively. The impact of this study is that the Fe(0)-catalytic Fenton oxidation would be an alternative to the traditional Fenton reaction to combat the environmental issues caused by the emerging micro-pollutants.