Efficient electrochemical degradation of ranitidine by a novel Bi-coated titanium oxide electrode: Performance and mechanism

• A novel Bi-Ti 4 O 7 anode was successfully fabricated for efficient RAN electro-oxidation. • Bi coating elevated the oxygen vacancy concentration and charge transfer on Ti 4 O 7 surface. • Direct electron transfer played an important role in RAN electro-oxidation by Bi-Ti 4 O 7 . • Bi-Ti 4 O 7 showcased a wide applicability under complex and realistic conditions. • RAN toxicity could be significantly reduced after electro-oxidation by Bi-Ti 4 O 7 . Ranitidine (RAN) is a commonly prescribed medication that poses ecological risks due to its potential to transform into the carcinogenic byproduct N-nitrosodimethylamine (NDMA) in the environment. Herein, we synthesized a novel bismuth-coated titanium oxide (Bi-Ti 4 O 7 ) electrode using a straightforward coating method and evaluated its effectiveness in the electrochemical oxidation of RAN. The Bi-Ti 4 O 7 electrode achieved a degradation efficiency of 90.41 % for an initial RAN concentration of 10 mg/L within 120 min, greatly outperforming the pristine Ti 4 O 7 electrode. The incorporation of Bi enhances the oxygen vacancies and charge transfer characteristics, facilitating direct electron transfer between RAN and the Bi-Ti 4 O 7 electrode. The potential degradation pathways of RAN by the Bi-Ti 4 O 7 electrode included C–S bond cleavage, C–N bond cleavage, and electrophilic oxidation. No NDMA was generated during the oxidation process, and the toxicity of RAN oxidation intermediates was greatly reduced. The Bi-Ti 4 O 7 electrode demonstrated excellent stability, maintaining over 90 % degradation efficiency across 30 cycles, and showed wide applicability across different pH levels and wastewater types with negligible Bi ion release (0.148 µg/L). These results underscore the potential of Bi-Ti 4 O 7 as an effective and sustainable solution for RAN-polluted wastewater treatment.