Precise Adsorption Behavior and Mechanism of Ni(II) ions on Nano‐Hydroxyapatite: Fid-Bau Portal

Precise Adsorption Behavior and Mechanism of Ni(II) ions on Nano‐Hydroxyapatite

Zhang, Jun / Wang, Deping / Zhou, Jun / Yao, Aihua / Huang, Wenhai

The goal of this study was to synthesize use of hydroxyapatite as a high‐efficiency adsorbent for Ni(II) ions, and to study its adsorption behavior. Three tests— Fourier‐transform infrared spectroscopy, transmission electron microscopy, and Brunauer‐Emmett‐Teller —were carried out to determine the chemical functionality of the hydroxyapatite powders, to observe its crystal morphology, and to measure the specific surface area. Results indicate that proves the n‐HA synthesized by chemical precipitation is an effective adsorbent for the removal of Ni(II) ions from water solution. The synthesized, needle‐like nano‐hydroxyapatite (n‐HA) have a uniform average size of 31.9 × 21.3nm, a large specific surface area (135 m²/g), and typically is a weak crystal with a broad pore distribution. The adsorption isotherm shows the Langmuir model is applicable only when the initial Ni²⁺ concentration is lower than 0.1 mol/L. Multilayer adsorption was attributed to uneven pore distribution that occurred at higher Ni²⁺ concentration. The adsorption of Ni²⁺ onto n‐HA was attributed to electrostatic attraction, ion exchange, and dissolution‐precipitation reaction. As the result, Ni²⁺ substitutes Ca²⁺ and binds with the oxygen atom on the surface, which resulted from the change in crystal‐phase composition and in the binding energy of surface elements of n‐HA before and after adsorption.