The Adsorbing Colloid Flotation of Fluoride Ion by Aluminum Hydroxide in Aqueous Media

Abstract
Up to 15.7 ppm fluoride can be removed from solution, pH 7.3 to 7.8, by adsorption onto colloidal aluminum hydroxide at a concentration of 40 ppm Al. This adsorbing colloid-adsorbed ion combination is then removed by foaming with 40 ppm sodium lauryl sulfate. After 30 min the concentration of fluoride is 0.0 ppm. The concentration of aluminum is also 0 ppm. Efficiency of removal slowly decreases with increasing ionic strength. Chloride ion interference is minimal.