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

[Display omitted] • DTPA enhanced SMT removal by nZVI/H 2 O 2 process at circumneutral pH in groundwater. • DTPA could complex with Fe2+ to prevent the surface passivation of nZVI. • The Fe2+-DTPA complex could rapidly decompose H 2 O 2 to produce OH. • nZVI/DTPA/H 2 O 2 process could effectively reduce biological toxicity of SMT. • nZVI/DTPA/H 2 O 2 showed an acceptable degradation of SMT in different water matrix. The present study proposed a promising heterogeneous Fenton-like process that a chelating agent (diethylenetriaminepentaacetic acid, DTPA) was introduced into the nZVI/H 2 O 2 system to improve its oxidation capacity for abatement of sulfamethazine (SMT) at circumneutral pH in the simulated groundwater. The nZVI/DTPA/H 2 O 2 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 H 2 O 2 to produce OH and other free radicals. The degradation patterns of SMT in the nZVI/DTPA/H 2 O 2 system were inferred on account of density functional theory (DFT) calculation and the detection of intermediates via LC-MS analysis. Besides, nZVI/DTPA/H 2 O 2 process could effectively reduce biological toxicity of SMT by prediction based on QSAR analysis. The coexisting ions such as Cl−, SO 4 2−, and humic acid (HA) had negligible influences for the oxidative abatement of SMT, while HCO 3 − had a concentration-dependent inhibitory effect. The oxidation capacity of nZVI/DTPA/H 2 O 2 process in actual water matrix and different pollutants were also discussed. [ABSTRACT FROM AUTHOR]