FUNCTIONALIZATION OF CARRIER TRANSPORT MEMBRANES BY THE CONTROL OF MICROSTRUCTURE

1.根据促进传递理论，成功地建立了CO_2与胺反应的反应速率常数和反应平衡常数对CO_2渗透性的影响。具有中等化学平衡常数的胺有利于获得高的CO_2渗透性.用促进传递模型考察了微孔支撑膜的特性对分离效果的影响。研究发现，当载体不带电荷时，载体的厚度、孔隙率和弯曲度是影响促进传输速率的重要因素.采用低温等离子体技术在聚乙烯微孔膜上接枝丙烯酸，制备了聚乙烯接枝丙烯酸离子交换膜。用单质子化乙二胺（EDAH^+）浸渍PE-G-AA膜制备的促进传递膜（PE-g-AA-EDA）对CO_2和CH_4具有很高的选择性。这是由于PE-g-AA膜的高水含量导致的膜中的载流子的高迁移率，并且还由于AA接枝层的高离子位点（COO-）浓度导致的高载流子浓度。由于载体（EDAH^+）被静电力固定在膜中，因此膜是稳定的。考虑载体在离子交换膜中的扩散性，用所建模型模拟了CO_2的促进传递速率.采用等离子体接枝聚合法制备了含磺酸基的微孔离子交换膜。以银银为载体，制备的膜作为载体促进C2 H4的传输是非常有效的.用DSC法测定了交联度、含水量和未冻水含量对CO_2促进传输的影响，用时滞法测定了CO_2的扩散系数和溶解度，结果表明，交联度、含水量和未冻水含量对CO_2促进传输有影响。

1. The effects of reaction rate constant and equilibrium constant of the reaction between CO_2 and amine on the permeability of CO_2 were successfully formulated on the basis of facilitated transport theory. An amine with moderate chemical equilibrium constant was found to be favorable to obtain high CO_2 permeability.2. The effect of the characteristics of microporous support membrane was examined by the facilitated transport model. It was found that the thickness, porosity and tortuosity of the support are the important factors which influence the facilitated transport rate if the support has no electric charge.3. Ion exchange membranes (PE-g-AA membrane) were prepared by grafting acrylic acid (AA) onto microporous polyethylene (PE) membranes using low temperature plasma. Facilitated transport membranes (PE-g-AA-EDA) prepared by impregnating the PE-G-AA membranes with monoprotonated ethylenediamine (EDAH^+) showed very high selectivity of CO_2 over CH_4. This was due to high mobility of carrier in the membrane resulting from high water content of PE-g-AA membrane and also due to high carrier concentration resulting from high ion site (COO-) concentration of AA graft-layr. The membrane was stable because the carrier (EDAH^+) was held in the membrane by the electrostatic force. The facilitated transport rate of CO_2 was simulated by the proposed model by considering the diffusivity of the carrier in the ion exchange membrane.4. Microporous ion exchange membranes having sulfonic acid groups were prepared by plasma graft polymerization method. The prepared membranes were found to be very effective as the supports of facilitated transport of C2H4 using silver nitrate as the carrier.5. The effects of cross-linking ratio, water content and fraction of unfrozen water in PVA gel membranes impregnated with (EDAH^+) on the facilitated transport of CO_2 could be elucidated by the DSC measurement and the diffusivity and solubility of CO_2 measured by time-lag method.