Mechanisms and product toxicity of activated carbon/peracetic acid for degradation of sulfamethoxazole: implications for groundwater remediation

Carbon-based materials activated peracetic acid (PAA) to repair groundwater is an environmentally friendly and low-cost technology to overcome secondary pollution problems. In this study, thermally modified activated carbon (AC600) was applied to activate PAA to degrade sulfamethoxazole (SMX). And the effect of groundwater pH, chloride ion (Cl-), bicarbonate (HCO3-), sulfate ion (SO42-), and natural organic matter (NOM) on SMX removal by AC600/PAA process was studied in detail. PAA could be effectively activated by AC600. Increasing AC600 dose (10-100mg/L) or PAA dosages (0.065-0.39 mM) generally enhanced the SMX removal, the excellent performance in SMX removal was achieved at 50 mg/L AC600 and 0.26 mM PAA. The removal of SMX was well described by second-order kinetic, with the rate constant (k(obs)) of 10.79 M1s(-1),both much greater than the removal constants of PAA alone (0.034 M1s(-1))and AC600 alone (1.774 M1s(-1)).R-O.(CH3C(O)OO., CH3C(O) O.) and electron-transfer process were proved to be responsible for the removal of SMX while HO. and O-1(2) made little to no contribution to the novel PAA/AC600 system, which differs from typical advanced oxidation processes. The SMX can be removed effectively over a wide pH range (3-9), exhibiting a remarkable pH-tolerant performance. Sulfate ion (SO42-), dissolved oxygen (DO), NOM displayed negligible influence on the SMX removal. Bicarbonate (HCO3-) exerted an inhibitory effect on SMX abatement, while chloride ion (Cl-) promoted the removal of SMX. This showed excellent anti-interference capacity and satisfactory decontamination performance under actual groundwater conditions. Furthermore, the degradation pathways of SMX were proposed, there was no obvious difference in the acute toxicity of the mixed products during the degradation process. It will facilitate further research of metal-free catalyst/PAA system as a new strategy for groundwater in situ remediation technology.

Automated summary

The study investigates the use of carbon-based materials to activate peracetic acid (PAA) in the repair of groundwater, focusing on the degradation of sulfamethoxazole (SMX) using thermally modified activated carbon (AC600). The research examines the influence of groundwater pH, chloride ion (Cl-), bicarbonate (HCO3-), sulfate ion (SO42-) and natural organic matter (NOM) on the SMX removal process. The findings demonstrate that AC600 effectively activates PAA, and increasing doses of AC600 and PAA enhance the SMX removal, with bicarbonate inhibiting the process and chloride ion promoting it.