Paper Number
SC3 

Session
Suspensions, Colloids and Granular Media

Title
Polyelectrolyte - particle assembly in mixed hydrodynamic fields

Presentation Date and Time
February 13, 2017 (Monday) 10:50

Track / Room
Track 1 / Audubon B

Authors (Click on name to view author profile)

1. Wilkinson, Nikolas (University of Minnesota)
2. Metaxas, Athena (University of Minnesota)
3. Dutcher, Cari (University of Minnesota)

Author and Affiliation Lines (in printed abstract book)
Nikolas Wilkinson, Athena Metaxas, and Cari Dutcher
University of Minnesota, Minneapolis, MN

Speaker / Presenter 
Metaxas, Athena

Text of Abstract
Water-soluble polymers with ionizable groups, or polyelectrolytes, are used in a number of applications due to the polymers unique ability to form mesoscale structures in solution. There are a number of known potential mechanisms for the mesoscale solute assembly, including charge neutralization, polymer depletion, polymer bridging, polymer adsorption, and patch flocculation, but the impact of time-dependent chemical and hydrodynamic conditions on assembly kinetics and final microstructure still remains largely uncertain. We seek to improve understanding of the dynamics of particle-particle, polymer-polymer, and polymer-particle interactions in complex hydrodynamic flows. Here, we explore assembly dynamics using cationic polyacrylamide, a polymer commonly used in water treatment, and anisotropic Na-bentonite clay particles. 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). We will also discuss a novel use of Taylor-Couette (TC) flow, or flow between rotating concentric cylinders, for studying how the hydrodynamics effects assembly and structure of these materials during the flocculation process. TC flow offers a high degree of control over hydrodynamics during the flocculation experiment when compared to traditional flocculation experiments. We will present a new TC cell design that allows for radial injection of fluids into the annulus while both cylinders are rotating. The ports allow injection of the polyelectrolyte solutions into particle laden flows, to study floc formation and growth in a well defined hydrodynamic field. This work sheds more light on the complexities of polymer flocculation, towards improving dosing and treatment optimization for more efficient water treatment.