以乳化式液膜自水溶液中回收及分離胺基酸

Recovery and Separation of Amino Acids from Aqueous Solutions by Emulsion Liquid Membranes

王郁茵(Yu-Yin)

指導教授 ： 莊瑞鑫

元智大學/工程學院/化學工程與材料科學學系/碩士(2001年)

摘要

本論文主要利用胺基酸具有兩性離子的特性，根據兩種胺基酸其等電點之差異，調整水溶液中的pH值，使胺基酸分別呈現陽離子及陰離子之狀態，以酸性萃取劑二(2-乙基己基)磷酸（D2EHPA）為載體，探討應用乳化液膜技術分離及濃縮多成分胺基酸水溶液的可行性。
首先改變攪拌轉速，水溶液pH值，界面活性劑含量，內水相酸度，油膜相與內水相體積比，乳水體積比等來探討乳化實驗的操作條件。由實驗結果得知，隨著乳化液用量的增加和內水相氫離子濃度的增加，萃取效率顯著增加。另外，藉由控制攪拌轉速，及界面活性劑的用量來減少因滲透作用所造成之乳液膨潤現象，以及攪拌作用所造成乳液之破裂現象。
在探討雙成分胺基酸的選擇性時，發現兩胺基酸等電點差異越大時，其選擇係數越大，表示分離效果越好。Phe / Asp系統平衡後選擇係數介於6.4 ~ 50.2之間；Phe / Glu系統選擇係數介於5.4 ~ 7.4之間；但是在Trp / Phe系統選擇係數則在1.05左右，並不隨pH值而有改變且分離效果不佳。

關鍵字

胺基酸 ； 二(2-乙基己基)磷酸 ； 乳化式液膜 ； 萃取

並列摘要

The recovery and separation of amino acids from aqueous solutions by using emulsion liquid membrane had been studied in this research. Due to the zwitterionic character of amino acids, they had their specific isoelectric points (pI). Amino acids could exist as the cationic or anionic form by adjusting the pH value less and greater than the isoelectric points in aqueous solutions. Therefore, a cation-exchange carrier, D2EHPA, may be applied to the extract ion and separation of two amino acids.
The emulsification experiments were performed by changing mixing speed, pH value, surfactant concentration, strength of acid, the volume ratio of membrane phase to internal phase and the volume ratio of emulsion to feed phase. It was shown that an increase in the volume ratio of emulsion to feed phase and the concentration of the acid in the internal phase would enhance the recovery. On the other hand, the effect of osmotic swelling and mechanical breakage could be reduced by controlling surfactant concentration and the mixing speed.
About the selectivity of binary amino acids, it was found that the larger the difference of isoelectric points, the larger the selectivity. In the phenylalanine / aspartic acid system, the selectivity was in the range 6.4 ~ 50.2. In the phenylalanine / glutamic acid system, the selectivity was between 5.4 and 7.4. But in the tryptophan / phenylalanine system, the selectivity did not change with pH and remained low.

並列關鍵字

Amino Acid ； D2EHPA ； Emulsion Liquid Membrane ； Extraction

參考文獻

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