冷冻解冻法破除液体石蜡W/O乳状液

Demulsification of liquid paraffine W/O emulsion by freezing and thawing

冷冻解冻法是一种新型的破除W/O乳状液的物理破乳方法.为了揭示冷冻解冻破乳作用机制,本文以稳定性好的液体石蜡W/O乳状液为研究对象,采用差热扫描量热仪(DSC)与显微镜,研究了高黏度连续相液体石蜡体系的W/O乳状液的冷冻解冻破乳过程.结果表明:该破乳过程是一个渐进过程.当乳珠粒径均匀细小,小于5.5μm时,乳珠在冷冻解冻循环中逐渐长大,经多次冷冻解冻后完成破乳;然而当乳珠粒径较大时,如51μm,乳状液体系仅需单次冷冻解冻循环就可破乳较完全,破乳率超过90%.此外,乳状液含水量的增加有利于提高破乳效率.乳状液水相的凝固点受乳珠尺度的影响,但受含水量的影响不显著.当乳珠粒径较大时,水相凝固点随乳珠粒径的减小而降低;但是当乳珠粒径降至5.5μm时,乳珠粒径的改变对其影响已不明显.

The demulsification of water in oil （W/O） emulsion by freeze/thaw is a new physical demulsification method. By far, the demulsification process and mechanism are still unclear. By using a stable liquid paraffin emulsion as the object of study, the freeze/thaw demulsification process of W/O emulsion with a highly viscous continuous phase （oil phase） was studied with differential scanning calorimeter （DSC） and optical microscope. The results showed that the freeze/thaw demulsification was a gradual process. When the droplet was smaller than 5.5 μm, the emulsion system could be demulsified by several freeze/thaw cycles, and in the freeze/thaw cycles firstly the small droplets coalesced and grew, and then separated from the emulsion system. But when the droplet was larger, such as 51 μm, the demulsification would be complete only in one freeze/thaw cycle, with over 90% （vol） of demulsification ratio. In addition, it was found that the increase of water content was beneficial to demulsification efficiency. And it is the droplet size, not the water content affects the freezing point of water phase. When the droplet is larger, the freezing point temperature declines with the decrease of droplet size, the effect is not obvious when the droplet was smaller than 5.5 μm.