Studies on coagulation process of colloidal systems stabilized by adsorption of amphiphilic materials

1.通过与不同类型的反离子交换蒙脱土粘土悬浮液的介电、超声速度、电泳迁移率和阳离子-表面活性剂-吸附实验，了解体系的水化、吸附和混凝行为。结果表明，表面活性剂的吸附量在加入后数小时内达到最大值，随后逐渐减小，接近平衡值。这些结果表明，利用蒙脱土作为吸附剂有效去除废水中的疏水物质应考虑吸附动力学。研究了几种食品蛋白和糖基非离子表面活性剂的乳化性能和乳化稳定性。牛血清白蛋白（BSA）比β-乳球蛋白（β-Lg）更能形成稳定的玉米油乳状体。我们还证实，在pH值接近于BSA等电点的介质中，当离子强度低于约30 mM时，BSA稳定的乳状液非常不稳定，但在较高的离子强度条件下，BSA稳定的乳状液变得相当稳定。测定了辛基葡萄糖苷、月桂酸蔗糖、辛酸葡萄糖和辛酸乙酯水溶液的表面张力与浓度的关系，得到了它们的临界胶束浓度和表面过量量。用原子力显微镜测量了聚苯乙烯颗粒和硅板在阳离子表面活性剂溶液中的表面力曲线。结果表明，两层电斥力的作用随着表面活性剂浓度的增加而增强，并且存在某种来源于聚合物分子的位向力。在此基础上，利用椭偏光谱法测定了水溶液中自旋涂覆聚苯乙烯薄膜的膜厚和含水量。在阳离子表面活性剂溶液中，膜厚度减小，表明聚苯乙烯分子从界面脱落。

1.Dielectric, ultrasonic velocity, electrophoretic mobility, and cationic-surfactant-adsorption experiments were carried out on suspensions of montmorillonite clay exchanged with different types of counter-ions to understand the hydration, adsorption, and coagulation behaviors of the system. It was found the adsorption amount of surfactants became a maximum in a few hours after the addition and then gradually decreased approaching an equilibrium value. These results suggested that one should consider the kinetics of adsorption for the use of montmorillonite as an adsorbent to remove hydrophobic materials efficiently from waste water.2.Emulsifying power and emulsion stability was investigated for some food proteins and sugar-based nonionic surfactants. Bovine serum albumin (BSA) could form more stable corn oil emulsions than β-lactoglobulin (β-Lg). We also confirmed that in the medium near pH 5 which closed to the iso-electric point of BSA, emulsion stabilized by BSA was quite unstable if ionic strength was below ca. 30 mM, but it became rather stable at higher ionic strength conditions. Surface tension for aqueous solutions of octylglucoside, sucrose laurate, glucose octanoate, and allose octanoate was measured as a function of concentration to get their critical micelle concentration and amount of surface excess.3.Surface force curves between a polystyrene particle and a silica plate both immersed in cationic surfactant solutions were measured by using AFM apparatus. It was confirmed that the effect of repulsive electrical double layer force increased with surfactant concentration and there existed some kind of steric force originated from polymer molecules. Further, spectro-ellipsometry for spin-coat polystyrene thin film in aqueous solutions was performed to estimate the film thickness and water content in the film. In cationic surfactant solutions, the film thickness decreased which suggested coming off of polystyrene molecules from interface.