Chemical Reactions of Fluoride Removal by Chicken Bone Char

Abstract

 Chicken Bone Char(CBC) work effectively to remove fluoride ion from solution. It has been reported that the ion exchange between fluoride ion and the hydroxide ion is the dominant reaction in fluoride removal. However, the pH value of the solution changes much less than that expected from the ion exchange reaction between fluoride ion and hydroxide ion after CBC removes fluoride. In the current study, chemical reactions involving in fluoride removal by and CBC was investigated according to an ion budget in the solution during the fluoride removal. It was revieled that when NaF solution was used, CBC removed fluoride by ion exchange with phosphate ion, hydroxide ion followed by the reaction with CO₂ to produce bicarbonate, and an ion exchange with bicarbonate in CBC. On the other hand, when artificial well water containing calcium and magnesium was used, CBC showed a much higher rate in fluoride removal. The formation of calcium chloride and fluoroapatite seemed to acceralate the fluoride removal from the solution.