直接滲透技術(FO)已被應用在多種分離程序，如廢水處理、食物處理、海水淡化或 微鹹水回收。FO 是利用高滲透壓差，將水從進料端透過一個親水膜到吸引溶液的過程。 本計畫將製備適用於FO薄膜技術之醋酸纖維/三醋酸纖維(CA/CTA)複合膜，並藉由 效能佳且耗能少的FO薄膜與薄膜蒸餾(MD)複合技術，應用於水回收技術，使FO程序更 具效益。首先將CA/CTA以乾濕式法製備平板複合膜，以SEM、DSC、XRD、及接觸角 量測探討膜表面性質，並以FO系統進行透水率測試，探討CA與CTA比例及濃度、造孔 劑濃度及熱處理等條件對透水率之影響，以了解本計畫所製備之FO薄膜的效能，並與商 業膜的結果做比較。其次將製備CA/CTA中空纖維複合膜，希望藉由乾濕式紡絲法，並 結合造孔劑與內凝聚劑之組成變化以增加內表面孔隙度，達到多孔性中空纖維膜之製 備，以提高膜通量；另外比較CA/CTA比例及濃度、芯液流速、air gap距離及熱處理等 條件對透水率及膜結構與表面特性，以及封裝後測試FO系統，進行批次及連續式程序實 驗，以獲得製備薄膜的水通量、對MgCl2(吸引溶液)的阻絕率等性質。最後將FO與薄膜 蒸餾系統結合，以MD連續回收吸引溶液，以不同濃度之MgCl2及操作溫度等測試FO-MD 複合系統，期望達到高透水率及水質，且以數學模式描述FO及FO-MD複合程序的通量。 Forward osmosis (FO), has new applications in separation processes for wastewater treatment, food processing, and seawater/brackish water desalination. Through osmosis, water is transported from the mixed liquor across a hydrophilic membrane, and into a draw solution with a higher osmotic pressure. The main objective of this project is to prepare some membranes suitable for the FO process applies in the water recovery technology, thin and high water-selective. In the first year, thin and porous cellulose acetate/cellulose triacetate (CA/CTA) composite membranes will be prepared. SEM, DSC, XRD, and Contact Angle analyzer use to characterize the membranes. By conducting the batch FO process, the water flux and salt rejection for the prepared membrane were measured and compared with commercial FO membranes. In the second year of the project, CA/CTA composite hollow fiber membrane was spun via dry-wet spinning method. In addition, aqueous solvent solution was used as the bore liquid to increase inner surface porosity. So that it could achieve the objective of porous morphology design. In addition, FO with tubular modules was also studied theoretically and experimentally. Finally, an integrated forward osmosis-membrane distillation (FO-MD) hybrid system will be setup. A concentrated MgCl2 solution was employed as the draw solute in FO, while distillate water is a by-product during the re-concentration of diluted draw solution in (MD). To determine suitable operating conditions for the hybrid system, independent characterizations were carried out for both FO and MD processes using different MgCl2 concentrations as draw solutes in FO and different feed temperatures in MD. Simple mathematical models consistent with the experimental results will also develop for the FO and the FO–MD hybrid systems.
