磁性高分子复合水凝胶的制备及其对水中铜离子的吸附性能

以海藻酸钠和聚乙烯醇为骨架负载磁性纳米Fe_3O_4颗粒合成了两种磁性高分子复合水凝胶材料:一种是以Ca~(2+)交联制备的磁性海藻酸钙单网络水凝胶(SAPFe),另一种是以海藻酸钙和聚乙烯醇经循环冷冻解冻制成的磁性双网络水凝胶(DAPFe).利用SEM、FTIR、BET对合成的材料进行表征,并研究了SAPFe和DAPFe对Cu~(2+)的吸附性能.结果表明,DAPFe比表面积达89.01 m~2·g~(-1),平均孔径为2.2 nm,DAPFe比SAPFe具有更低的含水率、更高的交联程度、更发达的孔隙结构和更高的比表面积.DAPFe对Cu~(2+)的最大吸附量可达207.01 mg·g~(-1),远大于SAPFe(173.01 mg·g~(-1)).SAPFe和DAPFe对Cu~(2+)的吸附等温线均符合Langmuir模型,吸附动力学符合准二级吸附动力学模型.通过分析SAPFe和DAPFe吸附Cu~(2+)前后官能团的变化,发现磁性高分子复合水凝胶具有丰富的羧基和羟基功能性官能团,并通过与Cu~(2+)产生螯合作用实现去除.

Preparation of magnetic polymer hydrogel and their application in Cu(II) removal from water

Two kinds of magnetic polymer hydrogel materials were synthesized with sodium alginate, polyvinyl alcohol and Fe₃O₄ nanoparticles as novel magnetic adsorbents to remove copper ions from aqueous solution:One is the single network magnetic hydrogel (SAPFe) prepared by Ca²⁺ crosslinking, and the other is the double network magnetic hydrogel (DAPFe) made by the cyclic freezing and thawing of SAPFe. Magnetic Fe₃O₄ nanoparticles were mixed into the hydrogels to create magnetic response and effectively separated by using an external magnetic field. The hydrogels were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and BET surface area. The results show that the specific surface area of the DAPFe was 89.01 m²·g^-1 which is higher than that of SAPFe. The DAPFe has average pore size of 2.2 nm. The Maximum adsorption capacity of Cu²⁺ on SAPFe reaches 207.01 mg·g^-1, which is higher than SAPFe (173.01 mg·g^-1). The results indicate that the adsorption process for Cu²⁺ could be well described by the Langmuir adsorption isotherm model, and the adsorption kinetics follow the pseudo-second order kinetics equation. FTIR spectra before and after adsorption of Cu²⁺ on the SAPFe and DAPFe implies that the chelation between -COOH^-/-OH groups and Cu²⁺ is the main removal mechanism.