直流电场中O/W型油水乳液分离效果的研究

Separation effect of O/W emulsion in DC electric field

研究了O/W型油水乳状液在直流电场下的处理效果和特点。根据实验中的分层现象,把O/W型乳状液的电破乳过程分为清液层阶段、横向扩散返混阶段和上升-稳定阶段。施加的直流电场电压越高,乳状液的分层越快。在分层过程中,含有表面活性剂的乳状液会出现表面张力梯度。在电流和表面张力梯度的共同作用下,不同体系的乳状液会出现不同的分层和电流变化。由于布朗运动的影响,直流电场对直径小于7μm的油滴处理效果较差。当初始含油质量浓度为3 000 mg/L、直流电压为20~30 V时,处理后的出水含油质量浓度最低达到60 mg/L。

The demulsification effect and characters of O/W emulsion in DC electric field are studied.According to the stratification phenomena in the experiments,the whole demulsification process of O/W emulsion can be divided into three stages： water layer formation,re-emulsification with transverse diffusion and uplift-stabilization. The higher the voltage given,the faster the stratification.Some evidences confirm that O/W emulsion system with surfactant will appear surface tension gradient in the demulsification process. The current together with the surface tension gradient cause different demulsification processes and current variation for different emulsions.Due to the impact of Brown movement,DC electric field exhibits poor effect on the oil droplets with a diameter less than 7 μm. When the initial oil content of the emulsion is 3 000 mg·L^-1 and DC voltage is between 20-30 V,the lowest oil content after demulsification can reach60 mg·L^（-1）.