Adsorption of Fluoride from Aqueous Solution by Nano-hydroxyapatite

Nano-hydroxyapatite synthesized by sol-gel method was used to remove fluoride ions from aqueous solution.The adsorption mechanism and the effect of various parameters such as adsorption time,the pH value and initial fluoride concentration on the adsorption efficiency were investigated.The research results show that the adsorption equilibrium is achieved in 120min and the adsorption kinetics can be described by pseudo-second-order reaction model;the optimal pH value is about 6 and the maximum adsorption capacity is 10.55mg/g,and the amount of adsorption increases with increasing fluoride concentration;the nano-hydroxyapatite is an effective adsorbent for fluoride and the adsorption of F-fits in Langmuir adsorption isotherm.