Modifying activated carbon with hybrid ligands for enhancing aqueous mercury removal
Modifying activated carbon with hybrid ligands for enhancing aqueous mercury removal
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DOI：
10.1016/j.carbon.2009.03.047
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发表时间：
2009-07
期刊：
影响因子：
10.9
通讯作者：
Jianzhong Zhu;B. Deng;John Yang;D. Gang
中科院分区：
文献类型：
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作者：
Jianzhong Zhu;B. Deng;John Yang;D. Gang
为了提高水溶液中汞(Hg)的去除效果，采用硝酸和亚硫酰氯联合处理的方法对活性碳(AC)进行改性，然后与乙二胺反应，引入N-、S-和Cl-官能团。用扫描电子显微镜、红外光谱、X射线光电子能谱、元素分析仪和电位法对改性后的活性碳进行了表征。通过间歇实验测定了MAC吸附汞的动力学和平衡等温线。表征表明，有机-无机配体通过处理在AC表面上的加成是有效的，很可能是通过酰氯-碳反应。电位滴定结果表明，修饰后引入了更多有利于阳离子吸附的负电荷。动力学和等温线研究表明，MAC对汞的吸附速度比AC快，吸附速度比AC高，吸附速度比AC快，吸附速度比AC高，吸附效果比AC高，说明MAC对汞离子具有较高的亲和力。MAC对汞的吸附发生在较宽的pH范围内(4-10vs.5-7)，低离子强度似乎增强了汞的吸附。吸附等温线符合Freundlich模型，MAC对汞的强化吸附主要是通过配位原子(O、N和S)与汞离子通过表面络合、还原和离子交换等机制完成的。
In an effort to enhance mercury (Hg) removal from the aqueous solution, activated carbon (AC) was modified by a combined treatment of nitric acid and thionyl chloride, followed by the reaction with ethylenediamine, to introduce N-, S-, and Cl-containing functional groups. The modified activated carbon (MAC) was characterized by SEM-EDS, FT-IR, XPS, elemental analyzer, and potentiometry. Kinetics and equilibrium isotherms of Hg sorption by MAC were determined in batch experiments. Characterization indicated that additions of the organic–inorganic ligands onto AC surface by treatment were effective, likely through the acyl chloride–carbon reactions. Potentiometric titration showed that the modifications introduced more negative surface charges favoring cation sorption. Kinetics and isotherm studies demonstrated that the Hg sorption by MAC was faster (<30min) and higher (>200%) than that by AC, suggesting a high affinity of MAC for Hg ions. The sorption by MAC occurred in a wider pH range (4–10 vs. 5–7), and low ionic strength appeared to enhance Hg sorption. The sorption isotherms were best described by Freundlich model, and enhanced Hg sorption by MAC was primarily accomplished by the coordinations of ligand atoms (O, N and S) with Hg ions through the mechanisms of surface complexation, reduction, and ion exchange.