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 (diethylene-triaminepentaacetic 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)-O-center dot 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)-O-center dot 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.