Diethylenetriaminepentaacetic acid (DTPA)-reinforced fenton-like process for efficient abatement of sulfamethazine at circumneutral pH in simulated groundwater

The present study proposed a promising heterogeneous Fenton-like process that a chelating agent (diethylenetriaminepentaacetic acid, DTPA) was introduced into the nZVI/H2O2 system to improve its oxidation capacity for abatement of sulfamethazine (SMT) at circumneutral pH in the simulated groundwater. The nZVI/DTPA/H2O2 system possessed a high oxidation performance for the elimination of SMT under the selected experimental conditions within 45 min of reaction. OH was considered as the predominant radical special accountable for SMT degradation. The roles of DTPA in the reaction system mainly include complexing with Fe2+ to prevent the passivation of nZVI, and forming the Fe2+-DTPA complex to rapidly decompose H2O2 to produce OH and other free radicals. The degradation patterns of SMT in the nZVI/DTPA/H2O2 system were inferred on account of density functional theory (DFT) calculation and the detection of intermediates via LC-MS analysis. Besides, nZVI/DTPA/H2O2 process could effectively reduce biological toxicity of SMT by prediction based on QSAR analysis. The coexisting ions such as Cl−, SO42−, and humic acid (HA) had negligible influences for the oxidative abatement of SMT, while HCO3− had a concentration-dependent inhibitory effect. The oxidation capacity of nZVI/DTPA/H2O2 process in actual water matrix and different pollutants were also discussed.