Synthesis and Characterization of Iron Doped Hydroxyapatite for Defluoridation of Water and Antibacterial Activity

Abstract

Abstract Fluoride contaminated drinking water is a major concern due to its negative health effects experienced by people in many parts of the world. This study focused on the synthesis of HAp and Fe doped HAp from diammonium hydrogen phosphate (DAP), calcium and iron precursors using urea as fuel for defluoridation of water and antibacterial activities. The synthesis of HAp and Fe doped HAp were characterized by using thermogravimetric analysis; scanning electron microscopy, X-ray diffraction, and Fourier transform Infrared spectroscopic techniques. An average crystallite size of HAp and Fe doped HAp were 32.54 nm and 27.91 nm, respectively, showing Fe doping results in a decrease in crystallite size. Batch adsorption studies were performed to investigate the adsorption capacity and removal efficiency of hydroxyapatite such as the effect of the initial pH of the solution, contact time, adsorbent dose and initial fluoride concentration. The adsorption data were fitted by Freundlich isotherm model and pseudo second order kinetic. In real water samples, the maximum removal efficiency of fluoride was observed to be 82.9 % with 4.2 mg/g maximum adsorption capacity under the optimum conditions which indicated that the prepared hydroxyapatite can be used as adsorbents for the removal of fluoride from contaminated real water with good efficiency. The antibacterial activities of the synthesized HAp and Fe doped HAp were tested against gram-negative bacterial strains E. coli and against gram-positive bacterial strains S. aureus using disc diffusion method. The maximum inhibition zone of gram-negative bacterial strains E. coli was 11 mm for both HAp and Fe doped HAp.