Simulation and experimental study on precise aeration and electric field for synergistic demulsification of emulsified oil

Numerical simulations of the deformation, aggregation, and migration processes of emulsified oil droplets under the influence of a multiphase field were conducted using COMSOL software. Combined with laboratory experiments, an existing process was improved and optimized by introducing the concept of "precise aeration." The results indicate that aeration can enhance the efficiency of electrochemical demulsification, with the gas field accelerating the deformation, aggregation, and migration processes of the oil droplets. Leveraging the numerical simulation results, laboratory experiments were conducted to optimize the aeration intensity and duration, which were reduced to 1.5 L/min and 60 min. At this point, the oil content and chemical oxygen demand (COD) of the emulsified oil wastewater were only 4.98 mg/L and 101 mg/L, respectively. The demulsification mechanism was analyzed, revealing that under the combined action of the electric field and gas field, oil droplets underwent a polarization reaction and were aggregated into larger droplets. Aeration expedited the weakening of the mechanical strength at the oil-water interface of the droplets, which significantly improved the demulsification, coalescence, and flotation removal of the emulsified oil droplets. This study holds significant importance for the process improvement and mechanistic analysis of electrochemical demulsification for oil removal.