Coupled influences of particle shape, surface property and flow hydrodynamics on rod-shaped colloid transport in porous media

Huilian Ma; Carl Bolster; William P Johnson; Ke Li; Eddy Pazmino; Kathryn M Camacho; Aaron C Anselmo; Samir Mitragotri

doi:10.1016/j.jcis.2020.05.022

Coupled influences of particle shape, surface property and flow hydrodynamics on rod-shaped colloid transport in porous media

J Colloid Interface Sci. 2020 Oct 1:577:471-480. doi: 10.1016/j.jcis.2020.05.022. Epub 2020 May 25.

Authors

Huilian Ma¹, Carl Bolster², William P Johnson³, Ke Li³, Eddy Pazmino³, Kathryn M Camacho⁴, Aaron C Anselmo⁵, Samir Mitragotri⁶

Affiliations

¹ University of Utah, Geology and Geophysics, Salt Lake City, UT 84112, USA. Electronic address: huilian.ma@utah.edu.
² USDA-ARS, Bowling Green, KY 42104, USA.
³ University of Utah, Geology and Geophysics, Salt Lake City, UT 84112, USA.
⁴ University of California at Santa Barbara, Chemical Engineering, Santa Barbara, CA 93106, USA.
⁵ University of California at Santa Barbara, Chemical Engineering, Santa Barbara, CA 93106, USA; Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
⁶ University of California at Santa Barbara, Chemical Engineering, Santa Barbara, CA 93106, USA; School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138, USA.

PMID: 32505007
DOI: 10.1016/j.jcis.2020.05.022

Abstract

Hypothesis: Natural or engineered colloidal particles are often non-spherical in shape. In contrast to the widely-used "homogeneous sphere" assumption, the non-spherical particle shape is expected to alter particle-fluid-surface interactions, which in turn affect particle transport and retention.

Experiments and simulations: Polystyrene microspheres were stretched to rod-shaped particles of two aspect ratios (2:1, 6:1). The transport and retention behaviors of rods versus spheres were investigated in packed quartz sand columns and impinging jet systems. In parallel, a 3D trajectory model was employed to simulate particle translation and rotation, and to elucidate the role and underlying mechanisms of particle shape impact on transport.

Findings: Rods were observed to undergo rotating and tumbling motions in response to fluid shear from experiments and simulations. However, no distinct retention trends between rods and spheres were observed from column studies, despite BSA-coating on particles, Fe-coating on sand or velocity change. This was primarily due to the super-hydrophobic nature of colloid surfaces acquired from stretching process, which in hydrophilic sand columns, dominated particle-surface charge interactions. Simulations using colloids with randomly distributed charge patches qualitatively produced the observed insensitivity in retention respecting aspect ratio under low charge coverage (<30%). Hence, particle shape influences were strongly coupled with colloid surface properties and flow hydrodynamics.

Keywords: Colloid transport; Particle rotation; Porous media; Rod-shaped particles; Shape effect.