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.