新型吸附剂的合成、表征及其对Ni(II)的吸附研究

Study on the Synthesis and Characterization of a Novel Adsorbent and Its Adsorption Property to Ni(II)

利用滴加法合成了球形含Ni2+交联壳聚糖,并通过胺化引入大量活性氨基,再经除镍制成对重金属镍离子具有较好吸附能力的新型吸附剂[P-C-CTS(Ni)].通过Ni2+吸附容量的测定,IR及XPS分析,验证了合成技术路线的正确性.通过研究pH值对吸附量的影响,初步讨论了无柠檬酸根(Cit)配位体存在时,吸附剂对Ni(II)的吸附为螯合作用.通过Cit存在条件下(cNi=cCit=0.852mmol·L-1),吸附剂对Ni(II)离子和Cit的吸附量随pH值的变化,结合相应pH值下金属镍的形态分布,探讨了其对Ni(II)的吸附机理,研究认为不仅仅是简单的螯合作用,其吸附机理和吸附量与溶液中金属离子的存在形式有关,引入静电吸附原理解释了吸附剂对Ni(II)的吸附现象.

A novel polyaminated and cross-linked chitosan bead templated by Ni^2＋ ions [P-C-CTS（Ni）] was prepared by introducing epichlorohydrin and polyethylene polyamine to enhance rigidity and increase the adsorption sites. The P-C-CTS（Ni） with a higher adsorption capacity was obtained. The adsorption properties of P-C-CTS（Ni） to Ni（Ⅱ） were studied. The structures of semifinished products were determined by IR and XPS, which validated the synthesis of P-C-CTS（Ni） in desirable processes. The relationships between pH and adsorption capacities for nickel in the presence of citrate （Cit） ligands with nickel/citrate molar ratio 1 ： 1 （CNi = Ccit= 0.852 mmol·L^-1） were investigated, showing that the adsorption capacities of P-C-CTS（Ni） to Ni（Ⅱ） which depended on pH in the presence of citrate ligands were distinctly different from those in the absence of the ligands. With the distributions of nickel species and citrate species being in function of pH in the corresponding conditions, the adsorption mechanisms of P-C-CTS（Ni） including both chelation and electrostatic attraction were discussed.