High-efficiency electrocatalytic degradation of recalcitrant organics in real oil sands process water using engineered biochar-reduced graphene oxide-polyaniline composites electrode

• Biochar-RGO-PANI synthesized via electro-deposition, reduction, and polymerization. • Biochar-RGO-PANI exhibited outstanding structural and electrochemical properties. • Complete removal of recalcitrant organics and acute toxicity in OSPW by EO using Biochar-RGO-PANI. • Biochar-RGO-PANI achieved high current efficiency with low energy consumption in EO. An innovative ternary composite electrode, comprising biochar produced at a pyrolysis temperature of 600 °C (B600), reduced graphene oxide (RGO), and polyaniline (PANI), was successfully synthesized through a straightforward three-step process involving electrodeposition, electroreduction and electropolymerization. This composite electrode, termed B600-RGO-PANI, integrates the unique properties of its components, offering enhanced performance with an optimized structure and exceptional electrocatalytic properties, such as low internal resistance and reduced overpotential, which are key factors for efficient reactive oxygen species generation. Electrooxidation (EO) using the B600-RGO-PANI as the electrocatalytic cathode and boron-doped diamond anode in the remediation of real oil sands process water (OSPW), achieving the complete removal of fluorescence compounds, classical naphthenic acids (NAs), oxidized NAs, and heteroatoms-containing NAs·H 2 O 2 and • OH were found to be the major oxidative species in the EO system. The acute toxicity of OSPW was eliminated and the total organic carbon removal efficiency reached 95.7% after only 90 min of treatment. Additionally, the superior stability and reusability of B600-RGO-PANI, as well as the low energy cost (0.57 kWh/g NAs) of EO with B600-RGO-PANI further indicate the engineered passive treatment approach for OSPW remediation through the high-performance cathode.