Simultaneous removal of enrofloxacin and Cr(VI) using uniaxial wet wall dielectric barrier discharge plasma

Abstract

The pollution of water by antibiotics and heavy metals has attracted more and more attention of scholars. Enrofloxacin (EFA) is a typical third generation fluoroquinolone antibiotic, which is widely used in human activities. Hexavalent chromium has been a great threat to human health and ecosystem due to its high mobility, toxicity and carcinogenicity. In this study, EFA-Cr(VI) mixed solution was used as a typical antibiotic - heavy metal simulated wastewater. We used a uniaxial wet-wall dielectric barrier discharge plasma reactor to simultaneously transform Cr(VI) and remove EFA for the first time, and its universality in the degradation of heavy metal pollution caused by other antibiotics was explored, providing a new solution for the simultaneous rapid and efficient treatment of antibiotic and heavy metal-contaminated wastewater. Within 18 min, the presence of hexavalent chromium greatly increased the degradation rate of EFA from 65.1% to 94.6%. The removal rate of hexavalent chromium was increased from 63.9% to 98.3% by the presence of EFA. The effects of initial pollutant concentration, input voltage, gas velocity, liquid circulation velocity, pH, organic matter and heavy metal ions were also investigated in this study. Free radical scavenging experiments showed that •O2,-•OH and 1O played an important role in the detoxification of EFA. The Cr(VI) conversion experiments showed that the EFA degradation intermediates, hydrogen peroxide and •H were the main factors of Cr(VI) reduction in the EFA co-degradation system. The degradation pathway was inferred based on the measured EFA intermediates. The developmental toxicity of EFA and its degradation products was quantitatively studied. The results showed that the toxicity of EFA wastewater was reduced after DBD treatment.