Treatment of simulated berberine wastewater by electrochemical process with Pt/Ti anode

Abstract

The emergence of antibiotics in aquatic environment has led to an increasing concern about the potential environmental risks and the spread of antibacterial resistance among microorganisms. Electrochemical oxidation processes are promising technologies to treat low contents of toxic and bio-refractory pollutants in water. Anodic oxidation of berberine, the frequently detected antibiotic in surface waters, was carried out by using RuO2/Ti, IrO2/Ti, RuIrO2/Ti, and Pt/Ti electrodes. It showed that with Pt/Ti anode, the removal efficiency of berberine was significantly higher than that with the other electrodes. Moreover, all the four electrodes showed 3–5 times higher reaction rate constant in NaCl solution than in Na2SO4 solution. The addition of chloride salts increased the oxidation rate of berberines due to the formation of active chlorines. In the case of Pt/Ti anode and simulated berberine wastewater, the effects of applied anodic bias, initial pH, Cl− and berberine concentrations, and reaction time on the removal efficiency of berberines were investigated. Under the optimal conditions of applied bias of 2.0 V, initial pH of 5.0, and Cl− concentration of 0.1 mol/L, the removal efficiency was higher than 90.0 % after 1-h reaction when the berberine concentration was lower than 50 mg/L. The acute toxicity of the simulated berberine wastewater could be largely reduced under the optimum conditions. Ultraviolet–visible adsorption spectra and excitation–emission matrix fluorescence spectra also confirmed that although berberines could not be fully mineralized after 1 h of electrochemical treatment, most of them were easily oxidized and decomposed by the electrolysis, thus forming some intermediate products with simple aromatic structures. Based on the results obtained, the electrochemical process with Pt/Ti electrode can be a feasible alternative as a post-treatment or treatment for berberine wastewater.