鈉離子交換薄膜之製備與對甲醇／水溶液分離效能之探討

Preparation of Sodium Ion Exchanged SPSF Membranes and Application for Dehydration of Methanol/Water Mixture

本研究利用Ni＋離子型聚嗍碸離子交換膜製備成不同取代度鈉離子薄膜應用於甲醇水溶液之滲透蒸發分離，探討鈉離子取代對交換薄膜之親水性質、膨潤性、吸附特性、透過介質之擴散特性及滲透蒸發效能之影響，研究中顯示鈉離子取代聚嗍碸薄膜僅能小幅提升膨潤特性，但隨離子取代程度增加對於甲醇與水分子之作用力相當，因此造成鈉離子薄膜吸附甲醇與水分子能力相當，無法有效提高其吸附選擇性，但因離子作用力可能影響高分子交聯程度，離子交聯抑制薄膜之膨潤特性並因此降低溶質擴散速率，所以本研究顯示離子交聯可明顯增加其滲透蒸發透過分子之擴散選擇性，滲透蒸發之分離性能因而隨聚嗍碸磺酸化程度增加而增加其分離係數。研究中亦發現25℃、90%甲醇／水溶液操作條件下，薄膜具良好選擇性。由本研究結果得知適當程度鈉離子交換薄膜於甲醇／水溶液滲透蒸發時可以同時改善透過率與選擇性。

The purpose this investigation is to prepare sodium substituted membranes by ion exchange method with sulfonated polysulfone (SPSF) membrane and their application for dehydration of methanol/water mixtures. The degrees of substituted sodium ion on membranes were quantified to explore the effect of the ion substitution on the hydration, degree of swelling, adsorption properties, and pervaporation properties. It was found that the increase in degree of sodium substitution in membranes slightly increased the hydrophilic properties of membrane and also enhanced the swelling properties. The increase of sodium ion content in membranes may be induced an increase in inter polymer chain crosslinking in membranes. Thus the ion crosslinking lead to a decrease in degree of swelling and lowed the permeate transport through membranes. It was also found that the separation performance of ion exchanged membranes was enhanced by increasing the sodium content in membrane. The permeation rate and separation factor of ion exchange membrane can be improved by the ion crosslinking in sodium substituted membranes.