Wednesday, November 15, 2006 - 9:30 AM

Interfacial Retention of Colloids in a Glass Capillary Channel.

Volha Lazouskaya and Yan Jin. Department of Plant and Soil Sciences, University of Delaware, 155 Townsend Hall, Newark, DE 19716

Colloid-facilitated transport of contaminants in soil has been an acknowledged environmental issue for more than a decade now. An additional interest in colloidal transport in soil was recently caused by the increased concern about fate and transport of nanoparticles in soil. However, colloidal transport and retention in multiphase systems are still not completely understood. Natural soil is a very complex multiphase system; therefore, it is often represented with a model medium to simplify the investigation of occurring physical processes and governing mechanisms. The interfacial retention of colloids makes a significant contribution to overall colloidal transport and retention, particularly in unsaturated soil media. The present study investigates the parameters that affect the behavior of colloids on air-water interface and contact line in a model system under equilibrium. The emphasis is made on such parameters as colloid surface properties and solution surface tension. The principal elements of the employed experimental system include a glass capillary microchannel and a laser scanning confocal microscope, which allows the visualization of colloidal behavior at the pore scale. The study focuses on the forces and mechanisms that are responsible for colloidal retention. The presented results are based on a series of microchannel experiments and can be extended to relevant processes occurring at the pore scale in natural soil media.