Journal Article

Synergistic activation of persulfate by FeS@SBA-15 for imidacloprid degradation: Efficiencies, activation mechanism and degradation pathways

Liu, Ying, Xu, Zhongjun, Jiang, Mengyun, Liu, Peng, Zhang, Xirong, Chen, Xiaochun, Zhang, Tingting

2023

Overview

In this work, FeS supported SBA-15 mesoporous silica catalyst (FeS@SBA-15) was synthesized successfully, characterized and first applied to persulfate (PS) activation for the degradation of imidacloprid in wastewater. The as-prepared 3.5-FeS@SBA-15 presented an impressive imidacloprid removal efficiency of 93.1% and reaction stoichiometric efficiency (RSE) of 1.82% after 5 min, ascribed to the synergetic effects of improved FeS dispersion and abundant surface sites by SBA-15. Electron paramagnetic resonance spectra and quenching experiments proved that both SO 4 ·- and ·OH were produced in FeS@SBA-15/PS system, and SO 4 ·- played a dominant role in the degradation process. The S 2- can accelerate the cycling of Fe(III)/Fe(II) during activation and increase the steady-state concentration of Fe(II). More importantly, the constructed heterogeneous system exhibited an efficient and stable catalytic activity over a wide range of pH (3.0-9.0), temperature (283K-313K), inorganic ion (NO 3 - ) and humic acid (1-20 mg/L). Moreover, the density functional theory calculations were conducted to predict the potential reaction sites of imidacloprid. Based on eighteen identified intermediates, four main degradation pathways were proposed: hydroxylation, dechlorination, hydrolysis, and the ring cleavage of the imidazolidine. ECOSAR analysis indicated hydroxylation and dechlorination played a key role in the detoxification of the formed compounds. These findings would provide new insights into the application of FeS@SBA-15 catalyst in wastewater treatment and the removal mechanism of imidacloprid from wastewater.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Aquatic Pollution / Catalysts / Catalytic activity / Chemical synthesis / Dechlorination / Degradation / Density functional theory / Detoxification / Earth and Environmental Science / Ecotoxicology / Efficiency / Electron paramagnetic resonance / electron paramagnetic resonance spectroscopy / Electron spin resonance / Environment / Environmental Chemistry / Environmental Health / Environmental restoration / Environmental science / Ferrous Compounds / Humic acids / hydrolysis / Hydroxylation / Imidacloprid / Insecticides / Intermediates / Iron - chemistry / Iron sulfides / Neonicotinoids / Oxidation / Oxidation-Reduction / pollution / porous media / Radiation / Research Article / Silica / Silicon Dioxide - chemistry / Sodium / Spectrum analysis / stoichiometry / temperature / Waste Water Technology / Wastewater / Wastewater treatment / Water Management / Water Pollutants, Chemical - analysis / Water Pollution Control