ZnO Promoted Persulfate Activation in Discharge Plasma System for Ofloxacin Degradation

Abstract

This paper aims to investigate the promotion of persulfate (PS) activation by ZnO in discharge plasma systems for the degradation of ofloxacin (OFX). Scanning electron microscopy and transmission electron microscopy showed that ZnO nanoparticles were successfully prepared by a hydrothermal method. With an increase in the PS dosage, the removal efficiency of OFX first increased and then decreased. With an increase in the ZnO dosage, the removal efficiency of OFX showed a similar trend. Under the optimum 595 mg/L PS dosage and 295 mg/L ZnO dosage, the removal efficiency of OFX by plasma, plasma/ZnO, and plasma/ZnO/PS systems reached 53.6%, 82.8%, and 98.9%, respectively. Increasing the input power was beneficial to the degradation of OFX. ESR results showed that the addition of ZnO could further stimulate PS to produce more ·OH and ·SO4− than that of plasma alone. The capture agent experiment proved that ·OH, ·SO4−, ·O2−, and 1O2 all participated in the degradation of OFX. A total organic carbon (TOC) removal of 49.6% was obtained in the plasma/ZnO/PS system. Based on liquid chromatography-mass spectrometry (LC-MS) and the Toxicity Estimation Software Tool (TEST), degradation pathways and toxicity were analyzed. Compared to other technologies, it can be concluded that the plasma/ZnO/PS system is a promising technology for pollutant remediation.

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