Quantitative Study of Electrokinetic Transport in Porous Media by Confocal Laser Scanning Microscopy

Abstract

Refractive index matching of liquid and solid phases in a bed of porous spherical glass beads allowed the use of confocal laser scanning microscopy for a quantitative study of intraparticle electrokinetic transport phenomena. By recording transient profiles of fluorescent, charged, and uncharged tracers, a significantly faster mass transfer was demonstrated for the electrokinetically enhanced transport as compared to a diffusion-limited process. Intraparticle electroosmotic and electrophoretic migration velocities were found to produce nonsymmetric distributions of tracer inside a sphere, contrasting with the symmetric profiles observed for diffusive transport.