TiO2-loading modification on graphene aerogel particle electrode for electrochemical oxidation of TCH wastewater with low electrolyte concentration: Performance and mechanism

In this study, the synthesis of titanium dioxide nanotubes/graphene aerogel (TNGA) as a particle electrode and the application in the three-dimensional (3D) electrode for the treatment of low electrolyte concentration wastewater containing tetracycline hydrochloride (TCH) was studied. The effect of reaction parameters (electrode, electrolyte concentration, cell voltage, initial pH, ratio of TNGA mass to solution volume) on the degradation of TCH in an electrochemical system was investigated. At the optimum conditions (cell voltage 18 V, initial pH 6 and TNGA mass to solution volume ratio 2 mg/mL) predicted by the response surface methodology (RSM), a high TCH degradation rate (90.6 %) was obtained after 3 h. TNGA showed relatively high stability in the electrochemical oxidation of organic pollutants (82.3 %) even after fifty continuous cycling experiments. The quenching experiments and electron paramagnetic resonance (EPR) indicated that TNGA can generate singlet oxygen in the 3D electrode system. Two possible degradation pathways for TCH were given based on possible intermediates. This study first showed that TNGA is an excellent electrocatalytic material as a particle electrode in antibiotic elimination.