Influence factors and mechanism of removing fluorides with Fe-Type Sepiolite

A highly efficient new fluoride absorbent was prepared by modification of sepiolite with an iron chloride. The effects of absorbent size, duration, pH, raw concentration, co-existing anions on removal efficiency of fluoride were investigated. The experiments indicated that Fe-Type Sepiolite is an effective fluoride absorbent with the removal efficiency above 95% by dosage of 2 g/100ml and duration of 40 min. The optimum range size of the absorbent is between the range of 0.-1.25 mm, and pH is partially sub acidity or neutral. Co-existing anions such as NO₃^- and SO₄^2- has a little Influence on adsorption of Fluoride. According to the analysis of adsorption isotherm and regeneration of Fe-Type Sepiolite, the mechanism of adsorbed fluoride is mainly by chemical adsorption.