Efficient electrochemical oxidation of cephalosporin antibiotics by a highly active cerium doped PbO2 anode: Parameters optimization, kinetics and degradation pathways
Colloids and Surfaces A: Physicochemical and Engineering Aspects(2023)
摘要
Removing cephalosporin contaminants from aquatic environments is of great concern because of the hazards they pose to the environment and human health. In this study, a Ce-PbO2 anode with a SnO2-Sb intermediate layer was fabricated using an electrochemical deposition method and used for the electrocatalytic oxidation of cephalosporin antibiotics. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the successful preparation of the Ce-PbO2 anode and revealed that Ce doping resulted in a highly stable structure and crystallinity of the PbO2 crystals. Moreover, the Ce-PbO2 anode exhibited excellent electrochemical performance with higher oxygen evolution potential (1.56 V), larger electroactive surface area (1.104 C cm-2), smaller corrosion current density (1.796 x 10-4 A cm-2), and higher hydroxyl radical (& BULL;OH) yield (8.64 mM min-1 m-2) compared with the intermediate layer and PbO2 anode. The effects of major operating parameters, including current density (20-80 mA cm-2), electrolyte concentration (0.050-0.125 M), initial concentration of target compounds (5-75 mg L-1), and pH (2-10) on the removal efficiencies of cefradine (RAD), and cephalothin (CEP) at the Ce-PbO2 electrode were investigated. The research results illustrated that when electrolysis was carried out for 90 min at the optimal current density of 40 mA cm-2 , an initial concentration of 50 mg L-1 , and an electrolyte concentration of 0.10 M, the removal efficiency of RAD and CEP were higher than 99%. Additionally, the degradation process followed pseudo-first-order kinetics. The total organic carbon (TOC) removal efficiency of RAD and CEP was 60.6% and 68.2% after 240 min, respectively, under the optimal conditions. The energy consumption for RAD and CEP degradation was 1.74 and 3.04 kWh g-1 TOC, respectively. In addition, the Ce-PbO2 electrode exhibited good stability over nine consecutive cycles. Using UPLC-MS, the intermediate products of RAD and CEP were confirmed, and the degradation intermediates were completely oxidized to CO2 , H2O, and inorganic ions (SO42- , NO3-). During electrolysis, the intermediate toxicity was studied using Escherichia coli growth inhibition tests, and the growth inhibition rate was calculated. Considering these results, the Ce-PbO2 anode could be utilized to treat wastewater containing cephalosporin antibiotics with high efficiency.
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关键词
Electrochemical oxidation,Cefradine,Cephalothin,Ce-PbO2,Degradation mechanism
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