Adsorption of Zn 2+ from aqueous solutions by si‐substituted carbonated hydroxylapatite: Equilibrium, kinetics, and mechanisms

• Published in: Environmental progress & sustainable energy Vol. 37; no. 6; pp. 2073 - 2081
• Main Authors: Zeng, Rongying, Tang, Wenqing, Liu, Xing, Ding, Chunxia, Gong, Daoxin
• Format: Journal Article
• Language: English
• Published: 01.11.2018
• ISSN: 1944-7442; 1944-7450
• DOI: 10.1002/ep.12898

A kind of low‐cost silicon‐substituted carbonate hydroxyapatite (Si‐CHAP) powder was successfully fabricated by using eggshell powder, H 3 PO 4 , Ca(OH) 2 , Na 2 SiO 3, and Na 2 CO 3 under sonochemistry coprecipitation condition. Si‐CHAP could serve as an ideal adsorbent to remove zinc ion (Zn 2+ ) from aqueous solution. Under the optimized conditions, the removal efficiency of Zn 2+ in solution by Si‐CHAP could reach to 96.2%. The adsorption mechanism was investigated by X‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Notably, the adsorption process followed the Langmuir isotherm and pseudo‐second‐order model, and the saturation adsorption capacities were calculated to be 102.0, 103.1, and 105.3 mg g −1 at 293, 303, and 313 K, respectively. Thermodynamic studies indicated that the adsorption of Zn 2+ by Si‐CHAP is endothermic. Mechanism studies revealed that the dominate mechanism was chemical adsorption. These results showed that Si‐CHAP is an effective adsorbent for the removal of Zn 2+ from aqueous solution, and thus providing a good method to treat Zn 2+ in the waste water. © 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901–1907, 2018