Manganese removal from spiked kaolinitic soil and sludge by electromigration

In this paper the feasibility of Mn removal from soils by electromigration is presented. Several experiments were conducted with two kind of samples ( saturated and unsaturated) with the aim of understanding the behavior of Mn in a porous medium within an electric field. The unsaturated samples were prepared with properties similar to sludges, and the saturated samples had characteristics similar to a mine soil. An electric field with a constant p otential difference of 15 or 30 V DC was applied across the electrokinetic cell (100 mm length, 32 mm diameter), with the sludge sample containing 3 t o 5 g Mn/kg dry weight. The system was monitored for the voltage drop, curr ent intensity, electroosmotic flow of liquid through the sample, and the pH of the electrolyte solutions. The test duration ranged from 174 to 218 hou rs. Metal removal in the unsaturated samples was about 78%, i.e., the Mn re moved to the electrolyte solutions. However, in the saturated soils most of the Mn removed (74%) accumulated in a plain brown layer in the soil, very near the cathode, as Mn(OH)(2).