In situ polymer flocculation and growth in Taylor–Couette flows†,Soft Matter

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In situ polymer flocculation and growth in Taylor–Couette flows†
Soft Matter ( IF 2.9 ) Pub Date : 2018-10-08 00:00:00 , DOI: 10.1039/c8sm01694a
Athena Metaxas _{1,

2,

3,

4} , Nikolas Wilkinson _{1,

2,

3,

4} , Ellie Raethke _{1,

2,

3,

4} , Cari S. Dutcher _{2,

3,

4,

5}

Affiliation

Flocculation of small particulates suspended in solution is a key process in many industries, including drinking water treatment. The particles are aggregated during mixing to form larger aggregates, known as flocs, through use of a polyelectrolyte flocculant. The flocculation of these particulates in water treatment, however, are subject to a wide spatial variation of hydrodynamic flow states, which has consequences for floc size, growth rate, and microstructure. Floc assembly dynamics are explored here using a commercially available cationic polyacrylamide, commonly used in water treatment, and anisotropic Na-bentonite clay particles under a variety of hydrodynamic mixing conditions. A Taylor–Couette cell with the unique ability to radially inject fluid into the rotating annulus was used to study how specific hydrodynamic flow fields affect assembly and structure of these materials during the flocculation process. Faster floc growth rates and decreased floc fractal dimensions were observed for higher order flow states, indicating improved mass transfer of the polymer flocculant and breakage at the edges of the flocs (shear rounding), respectively. This work sheds more light on the complexities of polymer-induced flocculation, towards improving dosing and efficiency of large-scale operations.

中文翻译：

Taylor-Couette流中的原位聚合物絮凝和生长†

悬浮在溶液中的小颗粒的絮凝是许多行业的关键过程，包括饮用水处理。通过使用聚电解质絮凝剂，颗粒在混合过程中聚集形成更大的聚集体，称为絮凝物。但是，这些颗粒在水处理中的絮凝作用会受到流体动力流动状态的广泛空间变化的影响，这会对絮凝物的尺寸，生长速率和微观结构产生影响。在这里，使用可商购的阳离子聚丙烯酰胺（通常用于水处理）和各向异性的钠膨润土粘土颗粒，在各种流体动力混合条件下，研究絮凝剂的组装动力学。使用泰勒-库伊特（Taylor-Couette）单元具有将流体径向注入旋转环形空间的独特能力，以研究在絮凝过程中特定的流体动力流场如何影响这些材料的组装和结构。对于较高阶的流动状态，观察到更快的絮凝物生长速率和减小的絮凝物分形维数，分别表明聚合物絮凝剂的传质改善和絮凝物边缘处的断裂（剪切修圆）。这项工作更多地揭示了聚合物诱导的絮凝的复杂性，以提高大规模操作的计量和效率。分别表明聚合物絮凝剂的传质和絮凝物边缘的破损（剪切变圆）。这项工作更多地揭示了聚合物诱导的絮凝的复杂性，以提高大规模操作的计量和效率。分别表明聚合物絮凝剂的传质和絮凝物边缘的破损（剪切变圆）。这项工作更多地揭示了聚合物诱导的絮凝的复杂性，以提高大规模操作的计量和效率。

更新日期：2018-10-08

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