Preparation of a ruthenium-modified composite electrode and evaluation of the degradation process and degradation mechanism of doxycycline at this electrode

Electrocatalytic method is widely used in the treatment of antibiotic wastewater. In this study, an efficient and stable ruthenium/agarose/copper foam (Ru/AG/CF) composite electrode was prepared by making full use of the properties of agarose and Ru. This electrode not only has a good catalytic effect, but also has a high stability. The morphology, crystal structure, and element valence of the composite electrodes were observed and analyzed by SEM, XRD, and XPS, respectively. The electrodes can achieve a degradation efficiency of 79.12% for a 10 mg/L solution of doxycycline in 120 min. The kinetics of the doxycycline degraded by Ru/AG/CF electrode was found to be pseudo-first-order kinetics and was fitted to the Langmuir–Hinshelwood model. Toxicity tests on doxycycline degradation solution using E . coli showed that the toxicity of doxycycline degradation solution was basically negligible and had a certain degree of safety. The products of doxycycline were analyzed by hydroxyl radical detection experiments using LC-MS. The degradation pathway of doxycycline was proposed. The removal efficiency of doxycycline was basically unchanged after 10 consecutive applications. The good degradation efficiency, good reusability and good safety showed that the electrode is a promising material for practical applications in water treatment. In this paper, Ru/AG/CF composite cathodes were prepared for the electrocatalytic degradation of doxycycline. OH and H were generated on the electrode surface, and a series of oxidation and reduction reactions were carried out on doxycycline, and doxycycline underwent ring-opening and cleavage reactions, which finally decomposed doxycycline into tiny molecules. • Preparation of Ru/AG/CF cathodes with good electrocatalytic properties. • Degradation of doxycycline solutions by reduction reactions with Ru/AG/CF cathodes. • The reaction mechanism of Ru/AG/CF cathode surface was investigated and the degradation pathway of doxycycline was deduced. • The toxicity of doxycycline degradation products was studied.