Mineralization of cefoperazone in acid medium by the microwave discharge electrodeless lamp irradiated photoelectro-Fenton using a RuO_2/Ti or boron-doped diamond anode

摘要

The mineralization of 125 mL of 50-300 mg L-1 cefoperazone (CFPZ) has been comparatively studied by electrochemical advanced oxidation processes (EAOPs) like anodic oxidation (AO), electro-Fenton (EF) and photoelectro-Fenton (PEF) with a RuO2/Ti or boron-doped diamond (BDD) anode and an activated carbon fiber (ACF) cathode. A microwave discharge electrodeless lamp (MDEL) was used as the UV source in PEF process. CFPZ decays always followed pseudo-first-order kinetics and their constant rates increased in the order: AO EF MDEL-PEF, regardless of anode types. Higher mineralization was achieved in all methods using BDD instead of RuO2/Ti, while the most potent BDD-MDEL-PEF gave 88% mineralization under its optimum conditions of 0.36 A, pH 3.0 and 1.0 mmol L-1 Fe2+. The synergistic mechanisms were explored by quantifying the electrogenerated H2O2 and formed (OH)-O-center dot, in which 2.27 and 2.58 mmol L-1 H2O2 were accumulated in AO-H2O2 with RuO2/Ti or BDD anode, respectively, while 92.0 and 263.5 mu mol L-1. (OH)-O-center dot were generated in EF with RuO2/Ti or BDD anode, respectively. The oxidation power of EAOPs with different anodes was also compared by measuring the evolutions of NO3- and NH4+ as well as four generated carboxylic acids including oxalic, oxamic, formic and fumaric acids.