Temperature effect on ionic transport during soil electrokinetic treatment at constant pH

Laboratory experiments and theoretical modelling generally proposed for electrokinetic soil processing consider isothermal conditions at room temperature. Important increases of the soil temperature, due to the Joule effect, have been observed during pilot or field-scale tests. The temperature effect on the transport of ionic species present in the pore solution is investigated when an electric field is applied through the soil mass. Laboratory experiments are run at 20 and 40 degrees C using kaolinite as soil model and one anion and one cation as model pollutants. An adapted methodology (pH control, steady state conditions) allows the measurement and the comparison of the ionic electrokinetic velocities at the two temperatures. Under the conditions developed, the temperature mainly influences the ionic velocities, which increase, for the two ions of interest, when the temperature rises. (C) 1999 Elsevier Science B.V. All rights reserved.