Interactions of polymers, surfactants, bacteria and particle surfaces

溶液或悬浮液中的任何表面都将通过吸附其周围的溶液中的物质来进行修饰。这些物种的吸附极大地改变了表面的性质，是各种重要过程的初步步骤。我们对带正电的表面活性剂和聚合物的吸附特别感兴趣，特别是后者可以作为絮凝剂的情况下。絮凝--高岭土(粘土)等颗粒的聚集--在造纸和饮用水澄清等过程中非常重要。表面活性剂可以吸附在表面上，并可以改变体系的性质，通常是通过溶解对水没有亲和力的物质来实现的。因此，表面活性剂的存在会干扰絮凝过程。虽然单一的絮凝剂和表面活性剂的作用已经被很好地定义，并且已经在双组分体系上做了一些工作，但关于包含多个组分的体系的了解要少得多。我们选择通过检测它们对红外光的吸收来进一步研究这些系统。不同的化合物吸收红外光的波长是不同的。我们能够从粘土和其他颗粒的甲醇悬浮液中制备稳定的薄膜，然后使用红外方法测量目标物种的特征吸光度。这些吸收的波长和强度的变化可以告诉我们，随着时间的推移，每个物种吸收到粒子上的方式，以及它如何与表面上的其他物种相互作用。我们将使用同样的方法监测石油-高岭土聚集体，并研究它们表面细菌生物膜的形成，以确定它们表面的生物膜形成是否在石油的生物修复中起重要作用。阳离子聚合物与其他溶解物种之间形成的络合物影响其作为絮凝剂的行为。这些络合物将通过它们在外加磁场(毛细管电泳法)中的运动以及它们在高岭土薄膜上的吸附能力来表征，随后进行红外吸收测量。

Any surface in a solution or suspension will be modified by the adsorption of species from that solution surrounding it. The adsorption of these species dramatically changes the surface properties, and is the preliminary step in a variety of important processes. We are particularly interested in the adsorption of positively charged surfactants and polymers, especially where the latter can act as flocculants. Flocculation - the aggregation of particles such as kaolin (clay)- is important in such processes as papermaking, and the clarification of drinking water. Surfactants can absorb onto surfaces and can change the properties of a system, often by solubilizing substances with little affinity for water. Thus, the presence of a surfactant can interfere with the process of flocculation. Although the actions of single flocculants and surfactants are well defined, and some work has been done on dual systems, much less is known about systems containing multiple components. We have chosen to further study these systems by examining their absorption of infrared (IR) light. The wavelength at which IR light is absorbed is distinctive for different compounds. We are able to prepare stable films of clay and other particles from their suspension in methanol, and then use IR methods to measure absorbances which are characteristic of the species of interest. The shifts in the wavelengths and intensities of these absorbances can tell us about the way each species absorbs onto the particle as a function of time, and how it interacts with other species on the surface. We will use the same approach to monitor oil-kaolin aggregates and study the formation of bacterial biofilms on them, in order to determine whether biofilm formation on their surface is important in bioremediation of the oil. The formation of complexes between cationic polymers and other dissolved species affects their behavior as flocculants. These complexes will be characterized by their motion in an applied field (capillary electrophoresis), and their ability to adsorb onto kaolin films, as followed by IR absorbance measurements.