脈衝電場掃流微過濾特性之探討

Use of Pulsed Electric Fields to Enhance Crossflow Microfiltration

陳冠廷(Guan-Ting Chen)

指導教授 ： 莊清榮

中原大學/工學院/化學工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300238

摘要

生化產品常有熱敏感、化學敏感等問題，因此生化分離程序中常採用不涉及相變化的膜過濾，且多以掃流方式操作，若在掃流過濾時伴隨電場，結合剪應、電泳及電滲透作用等對濾速的提升應有助益，但連續電場之能源耗損，是其無法被工業界採用主因之一，因而有脈衝操作被提出，但至今對其操作特性的了解仍非常有限。本研究以酵母菌懸浮液及BSA/酵母菌混合液進行脈衝電場微過濾實驗，探討電場脈衝頻率及電場強度等對濾速及混合液中蛋白質膜穿透率等的影響。
實驗結果顯示，以酵母菌懸浮液進行電場掃流過濾實驗時，固定電場之濾速隨電場強度提高而呈線性增加，針對洗淨及未洗淨之酵母菌懸浮液兩者雖介達電位顯著不同，但卻有相似之濾速表現。經脈衝頻率之過濾實驗，顯示以on(30)/off(30)有最佳的濾速表現，於過濾初段電場on時之濾速驟升量較不明顯而濾速衰減速率則較顯著，隨後有較相似的驟升與驟降量。
於電場強度1000~4000 V/m操作，脈衝頻率on(30)/ off (30)過濾30分鐘下，其濾液量約為固定電場者之94 ~82%，隨電場強度提高時，兩者之比率有些許下降的現象。將電場作用下的擬穩態濾速，Js，與預估值，Jav，相比較，可得高電場強度時，其Js明顯大於Jav。
對於BSA/酵母菌混合液之實驗結果顯示，於蛋白質的介達電位值甚低，吸附於粒子後粒子會產生聚集團使其介達電位值隨之降低，於脈衝操作下，其電滲透效應降低，瞬時濾速極值低於固定電場者，而平均濾速則較接近固定電場者之濾速。
關於混合液中蛋白質膜穿透率，結果顯示對0.2 μm微過濾膜，於電場強度2000 V/m之下的固定電場操作，其BSA膜穿透率約為91~99%，隨電場強度增加而提高，而於脈衝電場操作者，受電場強度影響甚微，穿透率皆維持在91%左右。

關鍵字

電場過濾 ； 脈衝頻率 ； 牛血清蛋白/酵母菌混合 ； 微過濾

並列摘要

The combination of shearing action and electric field has been recognized as an effective means of reducing both concentration polarization and membrane deposition in crossflow filtration. However, such a process has not yet received wide acceptance. One of the reasons for that is the excessive operation cost due to a high energy requirement. In order to minimize the power consumption, attention has been directed to the use of pulsed electric field. There have been brief reports that the use of pulsed electric field can lead to substantial improvements in filtration rates, but so far, the understanding of the principles of such processes is very limited.
In order to investigate the characteristics of pulsed electro- microfiltration for separating microbial cell suspensions, the experiments with yeast suspensions (with and without washed) by a flat-channel filter were carried out to show the effect of electric field strength and pulsed frequency on the filtration rate and the protein transmission when the suspensions were prepared from yeast/BSA mixtures.
When the filter was imposed with constant electric field strengths, its filtration rate increased almost linearly with the strength, but the increasing rates were greater than that of yeast mobility determined using electrophoretic measurement. The phenomenon that an instantaneous change of filtration rate associated with the imposed on or off of the pulsed electric field indicated clearly that the electroosmosis plays the major role in enhancing the filtration rate.
Among the four pulsed frequencies used in the study, in the range of on(10~120)/off(10~120), on(30)/off(30) always gives the better performance in increase of filtrate rate and its filtrate amount obtained was 94~82% of that from constant E ranging from 1000 to 4000 V/m. Thus, the pulsed operation has an obviously high electric energy efficiency. Based on the results under constant electric field strength and that without electric field, the average pseudo-steady state filtration rate in pulsed operation was also estimated and which values are somewhat lower than the experimental data, especially for the higher electric field strength.
For the filtration with yeast/BSA mixtures, it was observed that the electroosmotic and filtration rate are affected significantly by the zeta potential of BSA. The results obtained from the condition of pH=5, very near the isoelectric point of BSA, indicated that the transmission of BSA through the 0.2μm membrane is larger than 91% and increases with the electric field strength. However, a nearly constant transmission about 91% is observed for the pulsed operation with on(30)/off(30), independent of electric field strength used.

並列關鍵字

Pulsed frequency ； BSA/yeast mixture ； Microfiltration ； 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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