One-pot synthesis of arginine modified hydroxyapatite carbon microsphere composites for efficient removal of U(Ⅵ) from aqueous solutions

• Published in: Science bulletin Vol. 62; no. 23; pp. 1609 - 1618
• Main Authors: Yang, Dongxu, Wang, Xiangxue, Song, Gang, Zhao, Guixia, Chen, Zhe, Yu, Shujun, Gu, Pengcheng, Wang, Hongqing, Wang, Xiangke
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.12.2017
• Subjects: Adsorption; C@HAp/Arg composites; Interaction mechanism; U(VI); C@HAp/Arg composites; Interaction mechanism; U(VI); Adsorption
• ISSN: 2095-9273; 2095-9281
• DOI: 10.1016/j.scib.2017.10.018

Uranium was not only the main source of nuclear energy but also one of the long-lived radionuclide.Herein, a novel arginine modified hydroxyapatite carbon microsphere composites（defined as C@HAp/Arg） obtained promptly via a one-step mild hydrothermal method, was applied to remove U（Ⅵ） from aqueous solutions. Based on the characterization of transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier transformed infrared spectroscopy（FT-IR）, X-ray diffraction（XRD）and X-ray photoelectron spectroscopy（XPS）, the synthesized C@HAp/Arg presented globular morphology and abundant functional groups（e.g., —COO-）, which were beneficial to its combination with U（Ⅵ）. The interaction mechanism and removal capability of U（Ⅵ） on C@HAp/Arg were studied by batch adsorption technique and spectroscopy analysis. The results implied that U（Ⅵ） can form strong surface complexes on C@HAp/Arg. The kinetics adsorption of U（Ⅵ） followed pseudo-second-order kinetic model with high removal efficiency（$95% within 5h at pH 5.0）. The adsorption isotherms were well fitted by Langmuir model, implying that U（Ⅵ） uptake on C@HAp/Arg was monolayer coverage. It was found that the maximum adsorption capacities of CSs, C@HAp and C@HAp/Arg toward U（Ⅵ） were calculated to be 23.16,72.09 and 569.66 mg/g, respectively, at 298.15 K and pH 5.0, and thermodynamic parameters revealed that the adsorption processes of U（Ⅵ） were spontaneous and endothermic. In addition, effect of co-existed ions and CO32-concentrations demonstrated that U（Ⅵ） adsorption on C@HAp/Arg was weakly interfered by foreign ions and carbonate concentrations. More importantly, the adsorption performance of U（Ⅵ） on C@HAp/Arg was still over $87% after five cycles. Therefore, it was noted that the versatile C@HAp/Arg could be potentially used as a powerful building block for the enrichment and disposal of U（Ⅵ） from aqueous solutions, which could efficiently reduce the potential toxicity of U（Ⅵ） in the U（Ⅵ）-contaminated water.