以電滲透及流線電位決定薄膜之界達電位

Determining zeta potential of membrane by electroosmosis and streaming potential methods

許惠如(Hui-Ju Hsu)

指導教授 ： 莊清榮

中原大學/工學院/化學工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200178

摘要

膜過濾已被廣泛應用，所遭遇的最大困擾是膜結垢而導致分離效能降低，其中除了膜孔徑及膜材之親疏水性等因素會影響膜結垢之程度外，膜材電荷在膜分離中亦扮演重要的角色，膜電荷則是決定欲過濾物質與膜面相互作用力之主要變數，對於孔徑較小的薄膜其影響程度更大，由此可知膜電荷的量測將有助於膜過濾時對膜材之選擇提供一重要的參考依據。
本研究藉由通過膜孔之電滲透及流線電位量測方式，決定膜孔界達電位，另一方面，也利用平行膜面流線電位量測以決定膜面之界達電位，探討不同離子濃度和pH值時，膜孔與膜面界達電位之差異，並分析經蛋白質過濾及吸附後，薄膜電性的變化。對單一材質且孔徑對稱之0.2μm PC 膜，其膜孔與膜面之等電點極為接近，但當遠離等電點時，兩者間之電位差約10～20mV；針對膜孔之界達電位，以電滲透所決定之電位值較流線電位者為大。此外，PC薄膜之界達電位隨溶液離子濃度增加而減少，且除了10-3M KCl較低離子濃度時，膜面之電位與膜孔者有較大差異外，在其他離子濃度下，三個不同方法所決定的界達電位值差距皆在10mV之內。
PC薄膜經BSA溶液過濾後，薄膜之界達電位因受蛋白質吸附影響而與潔淨膜之界達電位有明顯的改變。對於較PC膜疏水之PES超過濾薄膜而言，潔淨膜與經蛋白質吸附後薄膜膜面之界達電位，除了在pH=4（等電點附近）時兩者膜面界達電位差距較小外，在pH＝5及7時皆有25mV之差異。除此之外，本研究也以理論模式分別探討各別層之孔徑、界達電位及孔隙度比等變因對複合膜材中，各層所佔總流線電位係數之比例之影響，指出當緻密層孔徑較小時，緻密層對總流線電位係數之影響越為明顯，緻密層孔隙度較小時亦有此現象。
針對有緻密表層之超過濾或奈米過濾膜，藉由平行膜面流線電位量測決定膜面電性是可行的，而膜孔界達電位之決定則以流線電位方法較方便且重現性較佳，但在決定薄膜之等電點時，則以電滲透法為較佳考量。

關鍵字

薄膜 ； 界達電位 ； 流線電位 ； 電滲透

並列摘要

It has been recognized that the electric charge of membranes plays an important role in the performance of membrane separations, since the fouling and selectivity of the membranes are affected significantly by this electrochemical property due to it exerts profound influence on the nature and magnitude of the interaction between the membrane and the charged particles in solutions. For the reason, there is much interest in characterizing the charge of the membrane.
In this study, theoretical analyses were performed to relate the correction factors for H-S model to the product of k and the pore radius or the spaced distance between membrane surfaces. The contribution of each layer to the overall electrokinetic phenomena in two-layer composite membranes was also analyzed theoretically in term of the physiochemical properties of each layer. Experiments of electroosmosis and streaming potential were implemented to determining the zeta potential of 0.2 mm isopore PC membr

並列關鍵字

membrane ； streaming potential ； zeta potential ； electroosmosis

參考文獻

左煒憶,”以電滲透及流線電位決定薄膜之膜孔界達電位”, 碩士學位論文, 中原大學化工所, （2001）

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Ariza, M.J., Canas, A., Benavente, “Electrokinetic and Electrochemical Characterizations of Porous Membranes “,Colloids and Surfaces A: Physicochemical and Engineering Aspects 189,247-256(2001)

Benavente, J., Jonsson, G., “Effect of Adsorption of Charged Macromolecules on Streaming Potential Values Measured with a Microporous Polysulfone Membrane”, Separation Science and Technology 32（10）, 1699-1710（1997）

Benavente, J., Jonsson, G., “Effect of Adsorbed Protein on the Hydraulic Permeability, Membrane and Streaming Potential Values Measured across a Microporous Membrane”, Colloids and Surfaces A: Physicochemical and Engineering Aspects 138, 255-264（1998）