Demulsification performance of oil-in-water emulsion in bidirectional pulsed electric field with starlike electrodes arrangement

A bidirectional pulsed electric field (BPEF) with starlike electrodes arrangement constructed by rodlike electrodes was investigated for demulsification of oil-in-water (O/W) emulsion in this work. By simulating the distribution of electric field intensity of parallel electrodes arrangement (PEA), concentric electrodes arrangement (CEA) and starlike electrodes arrangement (SEA) respectively, it was discovered that the SEA has the smallest proportion of the low field intensity area and the largest proportion of the high field intensity area, which could provide an appropriate electric field environment for demulsification of O/W emulsion. The effects of voltage, frequency, duty cycle and emulsion conductivity on demulsification of O/W emulsion were explored experimentally. For the O/W emulsion with an initial oil content of 3200 mg/L, the demulsification rate ascended with the increase of voltage, duty cycle and emulsion conductivity, but descended with the increase of frequency. The oil content and turbidity of the effluent firstly decreased and then increased with the increase of voltage, frequency and duty cycle, but increased steadily with the increase of emulsion conductivity. The optimal demulsification performance of O/W emulsion was obtained at the voltage of 500 V, frequency of 50 Hz, duty cycle of 40% and the emulsion conductivity of 2 μs/cm, and the oil content of the effluent could be reduced to 5.39 mg/L.