海藻酸钠改性超支化聚酰胺对重金属离子的选择性吸附性能

Selective adsorption of heavy metal ions by sodium alginate modified hyperbranched polyamide

采用共价键结合法,利用戊二醛,将海藻酸钠与端氨基超支化聚酰胺进行共价交联,制备出海藻酸钠改性超支化聚酰胺吸附材料,通过FT-IR对其结构进行表征,并考察了海藻酸钠改性超支化聚酰胺对水体中Pb^2+、Cd^2+和Zn^2+的吸附行为。研究结果表明,海藻酸钠改性超支化聚酰胺对Pb^2+、Cd^2+和Zn^2+的饱和吸附能力分别为210.56 mg·g^-1、130.53 mg·g^-1和129.11 mg·g^-1,且符合Langmuir等温吸附模型,可见海藻酸钠改性超支化聚酰胺对Pb^2+有明显的吸附选择性;而多元混合体系中的吸附实验表明,Cd^2+或Zn^2+与Pb^2+的共存可以对Pb^2+的吸附产生协同促进作用,而Pb^2+对共存重金属离子的吸附则是明显拮抗作用,二元混合体系中Pb^2+的饱和吸附量明显高于一元体系。但在三元混合体系中,海藻酸钠改性端氨基超支化聚酰胺对Pb^2+的吸附量基本不受共存离子Cd^2+和Zn^2+存在的影响。

Using glutaraldehyde as cross-linking agent,the sodium alginate modified hyperbranched polyamide was prepared by covalently linked sodium alginate and amino terminated hyperbranched polyamide.Its structure was characterized by FT-IR.The adsorption behavior of Pb^2+,Cd^2+ and Zn^2+ in water was investigated.The results showed that the adsorption of each heavy metal ion on sodium alginate modified hyperbranched polyamide was homogenously chemical adsorption.The maximum adsorption capacities of Pb^2+,Cd^2+and Zn^2+were 210.56 mg·g^-1,130.53 mg·g^-1 and 129.11 mg·g^-1,respectively,which could be seen that sodium alginate modified hyperbranched polyamide had an obviously adsorptive selectivity to Pb 2+.And the adsorption of each heavy metal ion conformed Langmuir isothermal adsorption model.Furthermore,the studies in multiple systems indicated that coexisting Cd^2+ or Zn^2+ had a synergistic promoting effect on Pb^2+ adsorption.However,Pb^2+ had a remarkable antagonistic effect on the adsorption of coexisting heavy metal ions.The saturated adsorption capacity of Pb^2+ in binary mixed system was significantly higher than that in single system.Moreover,in the ternary system,the adsorption capacity of Pb 2+by sodium alginate modified amino terminated hyperbranched polyamide was not affected by the presence of coexisting ions Cd^2+ and Zn^2+.