Colloidal Fouling of Ultrafiltration Membranes: Impact of Aggregate Structure and Size.
Colloidal Fouling of Ultrafiltration Membranes: Impact of Aggregate Structure and Size.
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DOI：
10.1006/jcis.1998.6040
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发表时间：
1999-04
影响因子：
9.9
通讯作者：
Waite;Schäfer;Fane;Heuer
中科院分区：
文献类型：
--
作者：
Waite;Schäfer;Fane;Heuer
悬浮液中形成的赤铁矿絮体的结构和尺寸与聚集在超滤膜上的滤饼的渗透性之间存在密切的耦合关系。由在扩散限制聚集条件下产生的絮凝物形成的饼的比电阻比由在反应限制聚集条件下产生的絮凝物形成的饼的比电阻低至少一个数量级。观察到类似的效果，无论是由盐浓度，pH值，或添加的有机阴离子控制的聚集制度。滤饼电阻的这种显著差异被认为是由赤铁矿组合的尺寸和分形特性引起的。流体流动通过这些集合体的容易程度将受到聚集体的分形维数和它们相对于初级颗粒尺寸的尺寸的影响（因为，对于分形聚集体，孔隙度随着聚集体尺寸的增加而增加）。聚集体的大小和强度也是渗透阻力、剪切诱导扩散和惯性升力的相对影响的重要决定因素，在本文报道的研究中，快速和缓慢形成的聚集体的颗粒沉积速率相对相似。这里提出的结果表明，通过控制骨料的尺寸和结构的蛋糕渗透性（和质量）的控制是一个领域，有进一步发展的范围，虽然在修改悬浮液中产生的骨料的分形特性的压实效果的性质和程度需要注意。版权所有1999年学术出版社。
A close coupling between the structure and size of hematite flocs formed in suspension and the permeability of the cake that accumulates on ultrafiltration membranes is observed. Specific resistances of cakes formed from flocs generated under diffusion-limited aggregation conditions are at least an order of magnitude lower than those of cakes formed from flocs generated under reaction-limited aggregation conditions. Similar effects are observed whether the aggregation regime is controlled by salt concentration, pH, or added organic anions. This dramatic difference in cake resistance is considered to arise from the size and fractal properties of the hematite assemblages. The ease of fluid flow through these assemblages will be influenced both by the fractal dimension of the aggregates and by their size relative to primary particle size (since, for fractal aggregates, porosity increases as the size of the aggregate increases). The size and strength of aggregates are also important determinants of the relative effects of permeation drag, shear-induced diffusion, and inertial lift and result, in the studies reported here, in relatively similar rates of particle deposition for both rapidly and slowly formed aggregates. The results presented here suggest that control of cake permeability (and mass) via control of aggregate size and structure is an area with scope for further development though the nature and extent of compaction effects in modifying the fractal properties of aggregates generated in suspension requires attention. Copyright 1999 Academic Press.