探討電場施加方式對掃流微過濾之影響

Effect of Electric Field Modes on the Crossflow Electro-Microfiltration

吳佳峻(Chia-Chun Wu)

指導教授 ： 莊清榮

中原大學/工學院/化學工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500380

摘要

摘要

膜過濾已廣泛應用於生物懸浮液之固液分離操作，但膜結垢的生成會造成濾速嚴重衰退及蛋白質穿透率或選擇性分離效能等的下降，因此，如何抑制膜結垢是解決其工程應用瓶頸之重要課題，其中以電場與掃流結合之電場膜過濾為該研究主題之一。本研究係以酵母菌、酵母菌/BSA混合液及PMMA等懸浮液進行電場微過濾實驗，探討固定、脈衝及交互等三種不同電場方式下對濾速、蛋白質穿透率及濾餅脫除等之影響進行研究。
於電場過濾中，濾速的提升往往來自膜材及濾餅的電滲透作用，若能有效藉由流線電位法決定膜孔表觀界達電位或複合膜材之整體界達電位，即可定量估算其電滲透流率，獲致與實驗數據甚一致的結果。酵母菌懸浮液以混合纖維酯(MCE)薄膜(孔徑範圍：0.65~3.0μm)過濾結果顯示，未施加電場下，以0.65μm孔徑膜過濾可得較高之擬穩定濾速，但對於帶電荷量不大之酵母菌粒子，電場施加下，電泳作用較不明顯，膜材電滲透為其濾速提升的主因，此時選用高膜孔電位值之1.2μm孔徑膜可獲致較佳過濾效能。
對於酵母菌/BSA混合液過濾結果顯示，在三種不同電場方式施加下，BSA因受電泳作用朝向膜面，其穿透率皆超過100％，且於交互電場下，濾餅附著量受反向電滲透及剪應力作用，明顯少於固定電場者，在實驗之操作範圍內，其BSA穿透率可高達147％。在PMMA懸浮液實驗中，因其粒子具高電位值，高膜孔電位膜材之反向電滲透對其濾餅的脫除較為顯著，且於交互電場操作下，懸浮液中之電導度及pH值較不易變化，可維持較佳之濾液品質。
對於本研究所選用之三種懸浮液，於電場作用下，其擬穩定濾速皆隨電場強度提高而約呈線性增加，但其實驗值皆高於理論估算值，此乃因電場作用而改變濾餅堆積結構及膜材電滲透作用使得有效壓差增大所致。

關鍵字

牛血清蛋白 ； 電場過濾 ； 酵母菌 ； 交互電場 ； 微過濾

並列摘要

ABSTRACT

Membrane filtration has been widely used in the separation of bio-suspensions, however, the membrane fouling sometime resulting in a serious decline of filtration rate and may also leading an unacceptable rejection of targeted component in selective separation is a serious bottleneck with the application of membrane filtration. With the demands for fouling prevention, the electric field used as a combined technique with crossflow filtration to control membrane fouling has been developed and recognized as an effective means for reducing both concentration polarization and membrane deposition in crossflow filtration. But so far, the understanding of the principles of such process is still very limited, especially for the application in the biomaterial suspension separations. The objective of this study is to investigate the effect of electric field mode, including fixed, pulse and alternating modes, on the crossflow microfiltration of yeast, yeast/BSA and PMMA particle suspensions.
Based on the result that there is a well agreement between the measured electroosmotic flux through a virginal membrane and the values estimated by Helmholtz-Smoluchowski model, it was concluded that the electroosmotic flux through membranes can be evaluated effectively with the apparent or global zeta potential of membrane pore determined by streaming potential method. It indicated clearly that the electroosmotic flux plays the major role in enhancing the filtration rate for the separation studied.
Experimental results from yeast suspension using mixed cellulose esters membrane in the pore size ranging from 0.65~3.0 μm showed that the pore size is an important factor in controlling the flux of microfiltration. However, as an electric field is applied onto the filter, the zeta potential in the membrane pore gives a significant influence on the filtration rate. For the filtration with yeast/BSA mixtures, it was shown that the transmission of BSA is larger than 100％ with the addition of electric field into filtration and, among the three electric field modes used, the alternating field leads a small amount of cake formation and a higher BSA transmission to a value of 147％.
Experimental results from PMMA suspensions indicated that the application of alternating electric field to sweep the deposited cake away is obvious under the condition of both the membrane pore and the particles having high zeta potentials. Because there is a more slight variation in conductivity and pH in recycled suspension and filtrate under alternating field mode, therefore, the application of such a mode also has an advantage to keep a better quality of filtrate and a better control of the operation.

並列關鍵字

BSA ； yeast ； microfiltration ； alternating electric field ； electro-filtration

參考文獻

陳信宇，“以脈衝式電場掃流超過濾分離牛血清蛋白溶液”，碩士學位論文，中原大學化工所 (2002)

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