Porous Carbon-Based Electro-Fenton Hollow Fiber Microfiltration Membrane for Efficient Ofloxacin Removal and its Transformation Mechanism

Abstract

This study investigated the removal performance of ofloxacin (a typical antibiotic) by a novel electro-Fenton enhanced microfiltration membrane. The membrane used in this study consisted of metal-organic framework derived porous carbon, carbon nanotubes and Fe2+, which was able to produce •OH in-situ via reducing O2 to hydrogen peroxide (H2O2). Herein, membrane filtration not only concentrated the pollutants to the level that could be efficiently treated by electro-Fenton but also confined/retained the toxic intermediates within the membrane to ensure a prolonged contact time with the oxidants. After validated by experiments, the applied bias of -1.0 V, pH of 3 and electrolyte concentration of 0.1 M were the relatively optimum electrolysis condition for OFL degradation. Under the relatively optimum conditions, the average OFL removal rate could be reach 75% with merely 5% membrane flux loss after 4 cycles operation. Via decarboxylation reaction, piperazinyl ring opening, dealkylation and ipso substitution reaction, etc., ofloxacin could be gradually and efficiently degraded to intermediate products and even to CO2 by •OH. Moreover, the oxidation reaction was preferred to following first-order reaction kinetics. This research would provide an alternative for advanced wastewater treatment, especially further eliminate the risk of antibiotic to natural ecosystems.

Keywords: Electro-Fenton, OH, Ofloxacin, Microfiltration membrane, Porous carbon