本研究旨在探討軟膠體粒子之微過濾機構及壓縮
性質。本研究採用三種不同分子量(70 kDa ' 500 kDa 及
2000 kDa) 的葡聚酵分別與過錳酸鉀交聯成葡聚醣-二氧
化錳(Dextran-MrlO2)之多孔性軟膠體，此種膠體粒子會
在受到壓縮後變形，並擠壓出內部水分。實驗結果發
現，此三種不同之軟膠體雖有相近的粒徑分佈、介達電
位及密度，但由於其機械強度及壓縮性質導致其過港、行
為有顯著之差異;當葡聚醣分子量越大，粒子的壓縮變
形越快達穩定，且由於葡聚醣分子量大的粒子越快壓縮
成緻密層(skin layer) ，故其過濾、速度會最慢，而掃流速
度增加，粒子所受的剪切力增加，但不同時間下粒子的
壓密程度不同，導致擬穩定;在遠不會隨著增加。此外，
本研究利用J慮、面上粒子之力平衡解析，探討操作條件對
濾餅成長的影響，發現葡聚醣分子量越大，粒子的附著
機率越小，導致初始濾餅易壓縮地越緻密，故粒子成長
厚度越簿，阻力越大。The mechanisms of compression and
microfiltration of soft particles are studied. Different kinds
of Dextran-MnO gel particles are prepared depending on
2 different molecular weights of dextran (70, 500 and 2000
kDa). The porous soft particles are filtered in "dead-end"
and "cross-flow" microfiltration, respectively. Although
the mean sizes, zeta potentials and densities of these
particles are almost the same, their filtration characteristics
are far different due to their mechanical strengths and
compressibility. The deformation and compression of
particles may reach the pseudo-steady state more quickly
for the particles constructed with higher molecular weight of dextran. The quicker skin-layer formation leads to a
lower filtration rate. Although the shear stress acting on the
membrane surface increases with increasing cross-flow
velocity, whether the pseudo-steady filtration rate will be
increased or not is dependent on the cake compression
course. Moreover, the probabilities of particle deposition
on the membrane surface under various conditions are
estimated based on a force balance model. An increase in
the molecular weight of dextran causes the cake
compression to be more serious and the filtration rate to be
lower.
關聯:
2008年輸送現象及其應用研討會論文摘要集 ( 2008 Symposium of transport phenomena and applications abstract book)
