Adsorption of Ni2+ by functionalized hydroxyapatite-chitosan composite

Abstract Chitosan and hydroxyapatite are commonly used materials for adsorption. In this work, chitosan was modified by polyethylene glycol and maleic anhydride. Subsequently, a hydroxyapatite-chitosan composite was synthesised by precipitation. The composite was characterised and analysed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Adsorption experiments were used to investigate the effects of external factors such as different pH values, adsorbent dosage, adsorption time and initial nickel ion concentration on the adsorption capacity of Ni 2+ and to discuss the mechanism of Ni 2+ removal by composites. The results show that the hydroxyapatite-chitosan composite has significant adsorption of Ni 2+ . The adsorption capacity of the hydroxyapatite-chitosan composite for Ni 2+ reaches 63.8 mg g −1 . The adsorption process is consistent with the pseudo-second-order kinetic model and the Langmuir isothermal model.