Enhanced Electro-Fenton Degradation of Ciprofloxacin by Membrane Aeration

Abstract

Electro-Fenton is a widely used electrochemical advanced oxidation process for the treatment of refractory organic pollutants, in which O2 input is required to generate hydrogen peroxide. The aeration mode directly affects the dissolution and stability of O2 bubbles in the solution, thus the rate of degradation. Herein, membrane aeration was introduced to the electro-Fenton degradation of ciprofloxacin in which O2 was dispersed into the liquid phase in the form of microbubbles through the ceramic membrane. Microbubbles can greatly improve the gas–liquid mass transfer efficiency of unit volume O2 to obtain an ultrahigh concentration of dissolved O2 up to 46 mg/L, thus improving the reaction rate. The effects of aeration mode, applied current, membrane aperture, aeration rate, and ciprofloxacin concentration on degradation rate were studied. Compared with the conventional electro-Fenton process using plastic pipe aeration, the membrane aeration-enhanced electro-Fenton (MAEF) system achieved a significant improvement in the degradation rate, and the reaction time required to achieve a 97% degradation ratio was remarkably reduced from 4 h to 10 min. Membrane aeration is an efficient approach to facilitating heterogeneous catalysis reactions involving the gas phase.