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

1.对不同类型反离子交换的蒙脱土悬浮液进行了介电、超声速度、电泳率和阳离子表面活性剂吸附实验，以了解该体系的水化、吸附和混凝行为。发现表面活性剂的吸附量在加入后的几小时内达到最大值，然后逐渐下降，接近平衡值。这些结果表明，使用蒙脱石作为吸附剂来有效去除废水中的疏水性物质需要考虑吸附动力学。2.考察了几种食品蛋白和糖基非离子表面活性剂的乳化力和乳状液稳定性。牛血清白蛋白(BSA)能形成比β-乳球蛋白(β-LG)更稳定的玉米油乳状液。我们还证实，在接近BSA等电点的pH 5附近的介质中，当离子强度低于30 mm时，BSA稳定的乳液很不稳定，但在较高的离子强度条件下，BSA稳定的乳液变得相当稳定。测量了辛基葡萄糖苷、蔗糖月桂酸酯、葡萄糖辛酸酯和异辛酸异辛酸酯水溶液的表面张力随浓度的变化关系，得到了它们的临界胶束浓度和表面富集量。3.利用原子力显微镜测量了聚苯乙烯颗粒和硅片在阳离子表面活性剂溶液中的表面力曲线。结果表明，随着表面活性剂浓度的增加，排斥性双电层作用力的影响增大，存在某种源于聚合物分子的位阻作用力。此外，还用椭圆偏振光谱仪测量了旋涂聚苯乙烯薄膜在水溶液中的厚度和薄膜中的水分含量。在阳离子表面活性剂溶液中，膜厚减小，表明聚苯乙烯分子从界面上脱落。

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.