(414f) Polyelectrolyte – Particle Flocculation in Complex Aqueous Solutions and Mixed Hydrodynamic Fields

Water-soluble polymers with ionizable groups, or polyelectrolytes, are used in a number of applications, such as drinking water treatment, to form mesoscale structures (‘flocs’) with solid particulates in solution. There are several known potential mechanisms for floc assembly, including polymer bridging and patch flocculation, but the impact of transient chemical and hydrodynamic conditions on assembly kinetics and final floc microstructure remains largely uncertain. Studying assembly kinetics and floc microstructure is particularly complex for systems with anisotropic particulates, such as clays, due to the variety of solution-dependent clay aggregate sizes and morphologies. Here, we explore assembly dynamics of anisotropic Na-bentonite clay particles with cationic polyacrylamide, a polymer commonly used in water treatment, in a variety of chemical solution conditions. We will highlight recent advancements in polymer-particle floc structure visualization that allows for improved understanding of the process variable effects on flocculation (Wilkinson et al., 2016). A Taylor-Couette cell with the novel ability to radially inject fluid into the annulus will be used to study how the hydrodynamics affect assembly and structure of these materials during the flocculation process. This work sheds more light on the complexities of polymer-anisotropic particle flocculation, towards improving dosing and treatment optimization for more efficient water treatment.