Potential of Sri Lankan Apatite as a fluoride removal Agent from aqueous solution against Various Apatite Materials

Abstract

As reported Sri Lanka it has a high fluoride contaminated ground water which was suspected as a cause for chronic kidney failure and there is an urgent need to treat fluoride contaminated drinking water to make it safe for human consumption by a low cost and convenient method. In this study potential of using Sri Lankan Apatite (SAp) as a defloration agent was studied and results were compared with other apatite materials. Adsorption experiments were performed on SAp, Sulphuric treated SAp (SSAp), Chicken bone char (CBC) and pre Hydroxyl Apatite (HAp). Since the raw SAp had no adsorbing capacity of fluoride, it was treated with sulfuric acid to produce HAp, however, sulphuric acid treatment for SAp did not yielded enough amount of hydroxy apatite as a fluoride adsorbent. Accordingly, higher leaching of fluoride into the solution was confirmed by the SSAp than that by the SAp. The fluoride removal capacities were in the order: HAp > CBC > SAp>SSA. The adsorption of fluoride by HAp and CBC was not well expressed by Langmuir isotherm but by Freundlich isotherm. It showed that HAp and CBC was a promising material for fluoride removal, therefore SAp should be further treated to extract phosphates to produce synthetic hydroxyapatite.