| Abstract: | 生化產品之回收純化技術是生物產業製程量產之重要關鍵，值得深入研究，其中薄膜過濾技術是最適於此類產品之連續式回收純化操作。薄膜過濾包括有微過濾、超過濾、奈米過濾及逆滲透等。微過濾操作適用於次微米粒子溶液之固液分離；超過濾操作一般應用於巨分子溶液之液液分離，如蛋白質或聚合物等膠體懸浮液；逆滲透應用去除水溶液中之鹽類，如海水淡化、超純水製造等。奈米過濾介於超過濾與逆滲透之間，此操作所涉及之分子分子量大約介於100至1000 Da，可應用於此類奈米等級溶液系統之濃縮與純化，如銨基酸、勝.、聚葡萄醣溶液之分離、乳酪產品之去礦物質處理、移除水中之有機物及重金屬，也對能通過超過濾膜之濾液進行去鹽脫礦之操作。對於奈米過濾而言，溶質穿透薄膜通常受篩選效應和電荷效應影響，此因奈米過濾薄膜之膜面通常會有帶電之情形。影響薄膜對溶質的排拒率的因素包括有操作變數(如操作壓力，溫度，,薄膜表面剪應力，進料濃度等)、溶液性質(如離子強度，pH值)、及薄膜電荷密度。 本研究計畫為三年期整合計畫之第三年計畫，第一年計畫中，已探討奈米級分子混合溶液於攪拌恆壓(dead-end)過濾系統之濾速行為，討論操作參數(攪拌速率、透膜壓差、溶液性質及薄膜特性等)對濾速及溶質排斥率之影響，並建立濾速及溶質排斥率之分析模式；第二年計畫中，將奈米級分子溶液之過濾系統延伸至連續式平板掃流(cross-flow)操作，探討掃流速度、薄膜方位等對分離性能之影響，並討論通氣操作對濾速及溶質排斥率之作用。本第三年研究計畫中，將探討提升奈米分子混合溶液濾速與分離特性的方法，包括有通氣操作模式、逆衝(back-flushing)操作模式等，以得出最佳之分離操作方式，對像為銨基酸與一較大分子之混合溶液，採用管式奈米薄膜之掃流過濾操作，探討操作條件對銨基酸溶液之分離與濃縮效率的影響，得出適當之操作模式，以達到創造高附加價值之產品為目標。The research and development on the technology for recovery and purification of bio-product are important in biotechnology. Membrane filtration has the highest potential to process the concentration and purification of bio-products in large scale. Membrane filtration includes microfiltration, ultrafiltration, nanofiltration and reverse osmosis. Microfiltration is usually applied to the solid-liquid separation of sub-micro particle solutions; Ultrafiltration is applied to the liquid-liquid separation of macromolecular solutions, such as protein or colloid solutions; Reverse osmosis is used in the desalination of seawater or the production of ultra-pure water. The operation of nanofiltration is applied to the separation of nanometer molecules with the molecular weight in order of 100 to 1000. It can be used to the separation of amino acid, peptide or cyclodextrin solutions, dairy product prodemineralized, or remove the dissolved organics or heavy metal from water. The solute transport in nanofiltration is dominated by the sieving effect as well as the Donnan effect due to the electric property of the membrane. The influences on solute rejection include operating parameter (e.g. transmembrane pressure, temperature, shear stress on membrane surface, feed concentration), solution property (e.g. ionic strength, pH value) and charge density of the membrane. This proposal is the third study of a three-year proposal. In first year proposal, the flux behavior of nano-molecular mixture solution in a stirred dead-end filtration system has been investigated, the effects of operating parameters (stir rate, transmembrane pressure, solution property, membrane characteristic, etc.) on the permeate flux and solute rejection have been discussed, and the analysis models of flux and rejection have also been developed. In the second year proposal, the work has been extended to a continuous cross-flow flat-membrane filtration system. The effects of cross-flow velocity and membrane orientation on the separation performance has been discussed, and the influence of gas sparging on the permeate flux and solute rejection has been also studied. Based on the results of above proposals, the methods of reducing the phenomena of concentration polarization and membrane fouling for improving the permeate flux and performance of membrane filtration will be studied in this third year proposal. The tubular inorganic membrane module will be used to investigate the separation of amino acid from a multi-component mixture. The techniques of the gas-sparging mode and the back-flushing mode will be applied to study the enhancement in the filtration performance in order to obtain an optimal operating mode about the separation and purification of nano-molecule solutes. |
