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Kinetic and thermodynamic adsorption of nickel (II) onto hydroxyapatite prepared from Snakehead (Channa striata) fish bone

Biomaterial exploration base on solid waste has been an attractive issue, particularly regarding economic and environmental demand. This work aimed to extract hydroxyapatite from snakehead fishbone through precipitation method and used to remove Ni(II). The hydroxyapatite product was characterized by using X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS) and Brunauer Emmett Teller (BET) method. Batch adsorption experiment includes pH solution, contact time and Ni(II) concentration. Pseudo-first order and pseudo-second-order were used to investigate the reaction mechanism and kinetic model, while adsorption equilibrium was evaluated according to Langmuir and Freundlich isotherm. XRD and FTIR spectra confirmed that hydroxyapatite was successfully extracted. The molar ratio (Ca/P) of hydroxyapatite was found at 1.70. The particle size of the hydroxyapatite was 48.77 nm. The pseudo-second-order is appropriate to describe the kinetic model while the adsorption mechanism follows Langmuir isotherm, which has an adsorption capacity of 5.359mg/g. The thermodynamic evaluation suggested the adsorption of Ni(II) is spontaneous in the endothermic process.