Electrophoretic mobility of some tropical soil clays: effect of iron oxides and organic matter

Abstract

Ž. The effect of organic matter and iron oxides on the electrophoretic mobility EM behavior of some colloidal clay fractions of some tropical soils was studied. The clays from the A-horizon of Ž. the soils were treated to remove organic matter oxidation by Na hypochlorite treatment, Ž . Ž ferrihydrite by acid ammonium oxalate and better crystalline iron oxides reductive dissolution. by dithionite–citrate–bicarbonate treatment. Organic matter and iron oxides particularly better crystalline ones contributed to the pH-dependent charge. The removal of organic matter resulted in Ž. an increase in the EM and isoelectric point iep. Defer ration decreased both the EM and iep of the soil clays. Increase in pH resulted in negative EM while salt concentration did not have consistent effect on the EM and iep values. q1999 Elsevier Science B.V. All rights reserved