mCMC-PEG/mCS-PEG双极膜的制备与表征

以Fe3+改性羧甲基纤维素(mCMC)和聚乙二醇(PEG)共混为阳膜;以戊二醛改性壳聚糖(mCS)和聚乙二醇共混为阴膜,制备了mCMC-PEG/mCS-PEG双极膜.以FTIR测定了膜红外光谱,以扫描电镜观察了膜表面和界面层的形态,以TG进行膜的热重分析.测定了mCMC-PEG和mCS-PEG不同比例共混膜的含水率、离子交换容量、溶胀度,及mCMC-PEG/mCS-PEG双极膜的电性能.研究结果表明,在双极膜材料中引入亲水性的聚乙二醇后,因分子间的相容性增大,故而提高了双极膜的离子交换容量,并减小了膜的溶胀性.当CMC∶PEG质量比等于10∶1和CS∶PEG质量比等于2∶1时所制得的双极膜具有良好的电化学性能,在酸碱溶液中机械强度高、溶胀小.

PREPARATION AND CHARACTERIZATION OF mCMC-PEG/mCS-PEG BIPOLAR MEMBRANE

A bipolar membrane is a polymeric layered structure composed of a cation ion-exchange layer and an anion ion-exchange layer.With respect to commercial applications,a bipolar membrane has high selectivity,low potential drop,acid and base resistance,solvent resistance,a wide pH range and good mechanical strength.mCMC-PEG/mCS-PEG bipolar membrane was prepared by a paste method,which was prepared by a blend of sodium carboxymethyl cellubse-plyethylene glycol(CMC-PEG) and a blend of chitosan-plyethylene glycol(CS-PEG),which were modified by Fe3 and glutaraldehyde(GA) as linking reagents,respectively.FTIR was applied to analysis the function groups of the bipolar membrane.Furthermore,the cross-section SEM photographs of the bipolar membrane illustrated a structure that consists of anion layer(mCS-PEG membrane) and cation layer(mCMC-PEG membrane).The charge densities of mCMC-PEG and mCS-PEG solutions were determined by the colloid titration.The water ratio,ion exchange capacity and swelling degree of mCMC-PEG membrane and mCS-PEG membrane were investigated.The current-voltage(I-V) curve across mCMC-PEG/mCS-PEG bipolar membrane was measured.The experiment results showed that CS-PEG and CMC-PEG blends appeared better compatibility and the introduction of PEG was beneficial to enhance the ionic exchange capacity and decrease the swelling degree of membrane.When mass ratio of CMC/PEG was 10/1 and CS/PEG was 2/1,mCMC-PEG layer and mCS-PEG layer were agglutinated tightly.The mCMC-PEG/mCS-PEG bipolar membrane appeared excellent electrochemical properties and high mechanical strength in acid and alkali solution.Meanwhile TG analysis of mCMC-PEG/mCS-PEG bipolar membranes exhibited a good thermal stability.mCMC-PEG/mCS-PEG bipolar membranes were used as the separator in the electrolysis cell for electro-generation organic acid.