TRANSPORT AND RETENTION OF CLAY PARTICLES IN SATURATED POROUS MEDIA. INFLUENCE OF IONIC STRENGTH AND PORE VELOCITY

A packed-bed column of fine sand system is depicted. A clay suspension is prepared from a smectite powder and deionized water.Three sets of experiments on column were carried out by making the pore velocity vary and using 3 chemical conditions : clay suspension with low ionic strength, and adjustement with NaCl and with CaCl2. Colloidal interactions are described by the DVLO theory. Analysis of typical breakthrough curves and comparison between solute and clay suspension with different ionic strenghs(adjusted or not)are made. A numerical model solving the equation of advection-dispersion is coupled with a first-order two-site kinetics theory.