Electrochemical reclamation of oil sands process water: Two and three-dimensional electrode configuration systems structured with different anode materials

Abstract

Several studies have indicated the potential of the electrochemical advanced oxidation process in oil sands process water (OSPW) reclamation; however, the variations in different electrode configuration systems and anode materials remain elusive. This study assembled a two-dimensional electrode system (2-DES) and a packed bed electrode reactor (PBER) for OSPW reclamation, of which boron-doped diamond (BDD) (non-active anode), dimensionally stable anodes (DSA-RuO2 and DSA-IrO2) and graphite (active anodes) were selected as the anode materials, while in PBER, spherical activated carbon (SAC) was added as the third electrode. Within the 2-DES, BDD achieved over 60% removal of chemical oxygen demand (COD) due to its excellent •OH generation ability, while DSAs generated the most active chlorine and were quickly consumed by organic matter during the first 30 minutes. However, mass transfer limitation restricted the 2-DES treatment efficiency regardless of the anode materials employed, particularly resulting in limited removal of naphthenic acids (NAs). Compared to 2-DES, PBER significantly improved the OSPW treatment under identical electrolysis conditions, achieving over 91% COD and 99% NAs removal using DSA-IrO2 + SAC. Because of the contribution of the third electrode in PBER, the performance differences between various anode materials were less substantial than in the case of 2-DES. Packed SAC enhanced the mass transfer performance and generation of radical oxidants during OSPW electrolysis, improving the OSPW electrochemical treatment process. Additionally, SAC adsorbed most free chlorine from the liquid phase, avoiding the formation of halogenated organic compounds in reclaimed OSPW.