Effect of selected conditions on fluorine recovery from a soil, using electrokinetics

Definition and implementation of adapted conditions for decontamination a f luorine polluted soil, using an electrokinetic process are described. Chemi cal batch extractions were first performed to evaluate the efficiency of so me parameters like pH, nature of reagents for fluorine removal from the soi l. The results showed that fluorine mobilization in the soil studied was pH dependent. The alkaline pH was favorable to fluorine recovery. In this med ium, F was the only predominant species in solution. Three laboratory elect romigration tests were subsequently performed under controlled pH condition s. The results indicated that the fluorine recovery from the soil was obtai ned using a simple addition of water at the cathode. In water added at the cathode allowed generation of hydroxide ions which were then transported by electromigration toward the anode, increasing pH in the soil in about 10 d ays. This in situ OH production has the advantage of limiting reagent addit ion. A pH control was then achieved at the anode (by flushing it with a dil ute alkaline solution) in order to prevent an undesirable low pH resulting from generation of hydronium ions. With such conditions, the part of mobili zable fluorine was removed in less than 30 days.