Degradation of ofloxacin in electro-Fenton system with adsorption and green self-regeneration function

Abstract

This report creatively puts forward a simple strategy of adsorption electro-Fenton degradation of ofloxacin coupling with green self-regeneration of adsorbent in wastewater. The shortcomings of short existence time and low utilization rate of OH were perfectly solved due to the adsorption of ofloxacin on zeolite in a cathode box made up of carbon felt. Another innovation is that the aerator is installed inside the cathode box. The internal aeration could suspend clinoptilolite particles to enhance mass transfer and the ofloxacin adsorbed on clinoptilolite could be degraded by OH, resulting in the green regeneration of zeolite and the adsorption and enrichment capacity of ofloxacin. What's more, internal aeration made OH move in the direction opposite to the enrichment of ofloxacin and improved OH utilization rate, realizing the efficient degradation of ofloxacin by electro-Fenton. The degradation efficiency of ofloxacin and TOC was 100% and 82.4 ± 0.4% with the initial ofloxacin concentration of 25 mg·L−1 at 105 min, respectively. The degradation of ofloxacin followed first-order kinetic model and degradation rate constant k is 0.0501 min−1. In multi-cycle operation the efficiency of ofloxacin degradation did not decrease. Ofloxacin was degraded in three pathways: 1) oxidation of fluorine atom on quinolone ring by OH and the subsequent replacement of fluorine atom with OH, 2) piperazine group oxidation and 3) oxazine ring oxidation. Adsorption and green self-regeneration provide a new idea for effective degradation of refractory organic compounds.