Adsorption mechanism of bone chars for defluoridation of groundwater

Abstract

The purpose of the research was to examine the adsorption fluoride onto pig bone char (PBC), chicken bone char (CKBC), and cow bone char (CBC) adsorbents. Bone char (BC) adsorbents were generated by charring process. The BC synthesis was characterized the physicochemical properties by X-ray diffraction (XRD) and N2 adsorption-desorption isotherm. According to the XRD result, PBC could produce higher percentage of hydroxyapatite (HAP) than those of CKBC and CBC adsorbents. Furthermore, the electrostatic interaction between BC surface and fluoride ion was dominant mechanism. The adsorption kinetics and adsorption isotherms were examined under batch condition. Along with the kinetic study, the adsorption fluoride on all of adsorbents reached to the equilibrium after 3 hours of contact time. The pseudo-second order model was found to fit well with the fluoride adsorption kinetic of all adsorbents. According to the adsorption isotherm result, all adsorbents showed adsorption isotherm, which best fitted with Langmuir isotherm model. The result reveled that the adsorption of fluoride on BC synthesized adsorbents affected by pH solution and anions. In addition, Low fluoride removal efficiency was observed when synthetic water of fluoride was used.