Synthesis of bone char from cattle bones and its application for fluoride removal from the contaminated water

This study is focused on the synthesis of bone char (BC) and its application in adsorptive removal of fluoride from the water. The BC was synthesized by the thermal pyrolysis of used cattle bones. In preliminary stage, BC was synthesized at different temperatures ranging from 350 to 700 °C and due to the higher surface area and adsorption capacity, BC synthesized at 350 °C was selected for further experiments. The XRD pattern of BC found better in agreement with the standard pattern of hydroxyapatite. FTIR analysis also signified basic spectra of hydroxyapatite with specific bands at wavelength of 3429, 1639, 1453, 1037, 604 and 566 cm⁻¹. Typical agglomerated structure of hydroxyapatite was witnessed in morphological examination with SEM. The specific surface area, total pore volume and the average pore diameter were found 79.34 m² g⁻¹, 0.041 cm³ g⁻¹ and 2.09 nm, respectively. The elemental chemical analysis revealed 1.71 Ca/P ratio. About 10.56 mg of fluoride was adsorbed on 1 g of BC. The adsorption isotherm data was briefly illustrated by applying Langmuir isotherm model and Freundlich isotherm model. In conclusion, BC is successfully synthesized and the highest fluoride adsorption capacity was achieved as compared with earlier studies.