Physicochemical characterization of potential colloids from agricultural topsoils

A method based on sedimentation and centrifugation steps has been developed to fractionate agricultural topsoils after suspension in water. A high release of potential colloids has been observed with low Ca2+ concentration under soil solid-to-water weight ratio conditions higher than 1/3. The colloidal stability is characterized in terms of particle size and electrokinetic properties. There is no systematic effect of the colloid phase organic carbon content varying from 2 to 5% on the critical coagulation concentration (CCC) and zeta potential results. Consequently, the observed CCC was tested by the Derjaguin-Landau-Verwey-Overbeeck theory by taking into account physicochemical properties of the colloid phase mineral content. (C) 2002 Elsevier Science B.V. All rights reserved