Effects of oil type and aqueous phase composition on oil-water mixtures containing particles of intermediate hydrophobicity
Effects of oil type and aqueous phase composition on oil-water mixtures containing particles of intermediate hydrophobicity
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DOI：
10.1039/b002582h
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发表时间：
2000-01-01
影响因子：
3.3
通讯作者：
Lumsdon, SO
中科院分区：
文献类型：
--
作者：
Binks, BP;Lumsdon, SO
描述了由部分疏水性球形二氧化硅颗粒稳定的乳液的行为，其中油类型在与水的混合物中变化，并且对于其中水被其他极性溶剂代替的含甲苯体系。通过在平板玻璃基底上进行接触角测量，我们推断颗粒在极性油水界面（酯和醇）处更具疏水性，优选油包水（w/o）乳液，而在非极性油水界面（烷烃）处更具亲水性，优选乳液类型是水包油（o/w）。甲酰胺体系与水的体系相似，但不能用甘油或乙二醇制备乳液。与表面活性剂稳定的乳液相反，我们发现优选的乳液类型取决于颗粒的初始位置，因为连续相是颗粒首先分散在其中的相。使用十一醇作为油，我们在粘性油包水乳液完全分解过程中观察到一个有趣的现象，涉及收缩以保持容器的形状。最后，我们确定了颗粒在甲苯和水之间的分配，并表明通过简单地增加水相的 pH 值即可使颗粒更具亲水性。通过这种方式增加水的润湿性，可以为破乳、浮选和消泡中涉及的不同含颗粒系统的行为提供新的线索。
The behaviour of emulsions stabilised by partially hydrophobic spherical silica particles is described for systems in which the oil type is varied in mixtures with water, and for toluene-containing systems in which water is replaced by other polar solvents. Using contact angle measurements on flat glass substrates, we deduce that particles are more hydrophobic at polar oil-water interfaces (esters and alcohols), preferring water-in-oil (w/o) emulsions, and more hydrophilic at non-polar oil-water interfaces (alkanes), with the preferred emulsion type being oil-in-water (o/w). Formamide systems are similar to those of water, whereas emulsions could not be prepared with glycerol or ethylene glycol. In contrast to a surfactant-stabilised emulsion, we find that the preferred emulsion type depends on the initial location of particles in that the continuous phase is the phase in which particles are first dispersed. Using undecanol as oil, we observe an interesting phenomenon during the complete breakdown of viscous w/o emulsions involving contraction to retain the shape of the vessel. Finally, we determine the partitioning of particles between toluene and water and show that particles can be rendered more hydrophilic by simply increasing the pH of the aqueous phase. An increase in the wettability by water in this way is used to shed new light on the behaviour of different particle-containing systems involved in demulsification, flotation and antifoaming.