ChE Seminar Series: Fundamentals and applications of diffusiophoresis: Particle motion induced by solute concentration gradients

Henry Chu, Ph.D.

Date(s) - 09/26/2023
9:00 am - 10:00 am

HPNP 1404


Henry C.W. Chu, Ph.D.
Assistant Professor
Department of Chemical Engineering
University of Florida

Title: Fundamentals and applications of diffusiophoresis: Particle motion induced by solute concentration gradients

Abstract: Diffusiophoresis refers to the deterministic motion of particles induced by a surrounding concentration gradient of solute. Diffusiophoresis receives much attention in recent years for its ability to manipulate colloid transport in a wide range of applications, including mixing and separation of colloids, enhanced oil recovery, drug delivery, to water and surface cleaning. In this talk, I present three projects in my group concerning fundamentals and applications of diffusiophoresis. In the first project, the motivation is an ongoing challenge of predicting the transport of diffusiophoretic colloids in hydrodynamic flows. I present our Taylor-dispersion-like macrotransport framework for predicting the transport of diffusiophoretic colloids under a steady pressure-driven flow and transient solute gradient. Our macrotransport equation requires O(103) times less computational runtime than direct numerical solution of the original, two/three-dimensional advection-diffusion equations.  In the second project, we examine drying of a colloidal suspension for ground-based and in-space manufacturing colloidal films. I present our direct numerical simulations of the advective-diffusive transport of an electrolyte-colloid suspension in a unidirectional drying cell.  Under both normal and microgravity, our results show an order of magnitude enhancement in the colloidal film thickness with diffusiophoresis. In the third project, recent experiments demonstrated diffusiophoresis in porous media for nanoparticle drug delivery, but existing theories cannot predict the colloid motion. We open a new area of research by developing a foundational mathematical model that can predict diffusiophoresis in porous media. A comparison between our model predictions and experiments demonstrates excellent agreements. Our model will motivate future theories and experiments, and enable efficient design of current and emerging applications.

Bio: Dr. Henry Chu is an Assistant Professor in the Department of Chemical Engineering at University of Florida (UF). He obtained a M.Phil. in Mechanical Engineering from The University of Hong Kong in 2012 under the supervision of Professors Chiu-On Ng and Kwok-Wing Chow.  He earned a Ph.D. in Mechanical Engineering from Cornell University in 2017 under the supervision of Professor Roseanna Zia. Following his Ph.D., he was a Postdoctoral Fellow in Chemical Engineering at Carnegie Mellon University, working with Professors Aditya Khair, Robert Tilton, and Stephen Garoff.  In 2021, he joined UF. The theme of his research is heterogeneous soft matter transport and design, covering topics such as complex fluid dynamics, colloid and interface science, electrokinetics, and rheology.  His research develops predictive multi-scale computational tools and fundamental theory to address National Academy of Engineering Grand Challenges for Engineering in these research areas, emphasizing on close collaboration with experimental groups to translate knowledge into applications. His work has been recognized through several awards, including Clyde W. Mason Scholarship by Cornell, Student Member Travel Award by American Institute of Physics, Global Faculty Fellowship by UF, and RSC Advances Emerging Investigator and Soft Matter Emerging Investigator by The Royal Society of Chemistry. Dr. Chu welcomes collaboration with academia, government agencies, and industry sponsors.