https://scholars.lib.ntu.edu.tw/handle/123456789/63780
標題: | 密集多孔粒子在無鹽溶液下之電泳現象 Electrophoresis of Porous Particles in a Concentrated alt-free Suspension |
作者: | 巫曉涵 Wu, Hsiao-Han |
關鍵字: | 電泳;電動力學現象;多孔粒子;不含鹽類溶液;反離子凝聚效應;極化效應;electrophoresis;electrokinetic;porous particle;salt-free solution;counter-ion condensation;and relaxation effect. | 公開日期: | 2009 | 摘要: | 本論文的研究主要以假性光譜法對帶電多孔粒子之電動力學現象進行數值模擬,討論多孔粒子在不含鹽類溶液(salt-free solution)的密集懸浮系統中之電泳行為,溶液中的離子來自於多孔粒子表面官能基解離而釋放的反離子,吾人以Kuwabara(1959)所提出的單位晶格模型(unit cell model)來描述此系統,求解耦合的電動力學方程組。 研究結果發現,當粒子帶電量都很小的時候,其電泳動度隨著粒子帶電量增加而線性增加,當帶電量超過某個臨界電量時,電泳動度會因反離子凝聚效應而趨於定值,並受鬆弛效應影響而有局部極大值的現象發生。然而,在密集度大的時候,反離子凝聚效應會隨粒子帶電量增加而逐漸消失,但是鬆弛效應依然存在並延後及提高電泳動度的局部極大值。在本研究中,吾人延伸Ohshima(2004)近似解,並以多孔粒子模型比對Nagasawa et al.(1958)聚電解質濃度對電泳動度影響的實驗結果。 In this study, we investigate numerically the electrokinetic phenomena of charged porous particle based on the pseudo-spectral method. The electrophoretic behavior of a concentrated dispersion of porous particles in a salt-free medium is analyzed theoretically. The counter-ion in solution comes from the charge-regulated surface of porous particle. We adopt respectively the Kuwabara’s unit cell model and solve the coupled electrokinetic equations those govern the electric field, the flow field and the ionic concentration field in these problems. In the results we found that, as the volume fraction and the surface charge of particle are small, the electrophoretic mobility increase with the charge linearly; however, when the charge exceeds a certain critical value, counter-ion condensation occurs and mobility will not change with the charge anymore. In addition, the mobility has local maximum due to relaxation effect. However, when the volume fraction is big, counter-ion condensation will decay as the surface charge increase. Meantime, relaxation effect still exists and lifts and postpones the mobility local maximum. In this study, we expand Ohshima’s approximate results in 2004. In addition, we compare our results with Nagasawa et al.’ which discuss the influence of polyelectrolyte’s concentration. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/187015 |
顯示於: | 化學工程學系 |
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ntu-98-R96524024-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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