无机盐浓度和种类对静电破乳的影响

Impact of Type and Concentration of Inorganic Salt Acting on Electrostatic Demulsification Process

为探究静电聚结破乳机理,采用显微实验研究的方法,深入考察不同无机盐浓度和种类条件下W/O乳状液分散相液滴在脉冲电场作用下的破乳聚并行为。实验发现,一定范围内,随溶于分散相无机盐浓度的增加,液滴电导率增大,极化作用力增强,迁移聚并速率加快,沉降分离效果提升。无机盐浓度过高时,极化作用力、离子冲击力激增,出现过度极化现象。电导率、界面张力、pH值和介电常数差别不大的条件下,液滴的极化效果主要取决于离子极化效应,高价盐的静电聚结速率显著增大。油水界面张力低、离子价位高的条件下,极易形成数量较多、长度极长的液链,降低了液滴的迁移聚并速率。上述研究成果为高效紧凑的静电聚结设备的开发提供了依据。

In order to investigate the mechanism of electrostatic coalescing demulsification, micro-experiment was carried out, and the demulsification and coalescing behavior of water droplets under the effect of impluse electric field in W/O emulsion with different inorganic salt type and concentration conditions was comprehensively studied. It was demonstrated that, with inorganic salt concentration increasing, electrical conductivity and polarization force of droplets increase, migrating and coalescing velocities speed up, sedimentation and separating effect raise to certain extent. However, when salt concentration is too high, the polarization force and ionic impact force increase sharply, which lead to excessive polarization. Polarization effect of water droplets mainly depends on ionic polarization effect when conductivity, interfacial tension, dielectric constant or pH value has only slight difference, and electrostatic coalescing velocity of water droplets containing high quantivalency inorganic salts increases greatly. Emulsion with low interracial tension and large ionic quantivalency hyperpolarization can easily form large quantity and long droplet chains during impulse electrostatic coalescing process, which reduces the migrating and coalescing velocity of droplets. This work provides good foundation for further development of effective and compact electrostatic coalescing equipment.