Retention of fluoride ions from aqueous solution using porous hydroxyapatite: Structure and conduction properties

Synthetic porous calcium hydroxyapatite (noted p-HAp) treated with different fluoride concentrations at room temperature in the presence of carbonate, sodium chloride and phosphate-rich media was investigated. The fluoridation rate of the porous calcium hydroxyapatite was 89% using 1 mol/L [F ^-] solution compared with 30% for crystalline hydroxyapatite (c-HAp). The high specific surface area of p-HAp (235 m ² g ^-1) compared with c-HAp sample (47 m ² g ^-1) has an important effect on the removal of fluoride ions from aqueous solution, when p-HAp was treated with high fluoride concentration to produce calcium fluorohydroxyapatite materials. Fluoride adsorption on porous hydroxyapatites (p-HAp) modified their structural and conduction properties.