Preparation of magnetic calcium silicate hydrate for the efficient removal of uranium from aqueous systems
Preparation of magnetic calcium silicate hydrate for the efficient removal of uranium from aqueous systems
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DOI：
10.1039/c4ra08678c
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发表时间：
2015
期刊：
影响因子：
3.9
通讯作者：
Hongsen Zhang;Qi Liu;Jun Wang;Jingyuan Liu;Huijun Yan;X. Jing;Bin Zhang
中科院分区：
文献类型：
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作者：
Hongsen Zhang;Qi Liu;Jun Wang;Jingyuan Liu;Huijun Yan;X. Jing;Bin Zhang
为了获得一种具有超强吸附能力、快速吸附速率和快速磁分离的铀吸附剂，通过声化学方法在磁性二氧化硅微球表面原位生长水合硅酸钙（CSH），制备了磁性水合硅酸钙（MCSH）。通过FTIR、XRD、TG、VSM、SEM、TEM和N2吸附-脱附方法对MCSH的化学成分、结构和形貌性质进行了表征。结果表明，具有介孔结构的MCSH是由CSH纳米片团聚而成。 MCSH的BET比表面积和饱和磁化强度分别确定为196 m2 g−1和15.4 emu g−1。基于合成的MSCH，研究了吸附等温线、热力学和动力学。吸附机理符合Langmuir等温线模型，在298 K时最大吸附容量为2500 mg g−1。计算的热力学参数表明，吸附过程符合伪二阶模型，是自发吸热的。 MCSH表现出快速高效的吸附行为，在前10分钟内就吸附了80%以上的铀（1000 mg L−1）。卓越的吸附能力和快速的吸附速率可能归因于CSH超薄纳米片的超高比表面积以及铀离子和钙离子的轻松交换。这些结果表明，MSCH 是一种用于从水系统中去除铀的优异吸附剂。
To obtain an adsorbent for uranium with superb adsorption capacity, a rapid adsorption rate and quick magnetic separation, magnetic calcium silicate hydrate (MCSH) is fabricated through in situ growth of calcium silicate hydrate (CSH) onto the surface of the magnetic silica microspheres via a sonochemical method. The chemical components, and structural and morphological properties of MCSH are characterized by FTIR, XRD, TG, VSM, SEM, TEM and N2 adsorption–desorption methods. The results show that MCSH with a mesoporous structure is constructed by an agglomeration of CSH nanosheets. The BET specific surface area and saturation magnetization of MCSH are determined to be 196 m2 g−1 and 15.4 emu g−1, respectively. Based on the synthetic MSCH, adsorption isotherms, thermodynamics and kinetics are investigated. The adsorption mechanism fits the Langmuir isotherm model with a maximum adsorption capacity of 2500 mg g−1 at 298 K. The calculated thermodynamic parameters demonstrate that the adsorption process, which is in accordance with a pseudo-second-order model, is spontaneous and endothermic. MCSH exhibits a quick and highly efficient adsorption behavior, and more than 80% of uranium (1000 mg L−1) is adsorbed in the first 10 min. The superb adsorption capacity and rapid adsorption rate are likely attributed to the ultrahigh specific surface area and facile exchanges of uranium ions and calcium ions of CSH ultrathin nanosheets. These results demonstrate that MSCH is an excellent adsorbent for uranium removal from aqueous systems.