Auto-electrokinetic flows in dead-end pores from mixed ion systems
Open Access
- Author:
- Kar, Abhishek
- Graduate Program:
- Chemical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- July 27, 2012
- Committee Members:
- Darrell Velegol, Thesis Advisor/Co-Advisor
- Keywords:
- auto-electrokinetics
electrokinetics
CaCO3
dead-end
diffusiophoresis - Abstract:
- In this dissertation, I demonstrate fluid flows using a mechanism called diffusiophoresis. Using modeling and experiments, I show that fluid flows and particle migration can occur over a distance of merely 1 millimeter phenomenon. Based on the physics behind diffusiophoresis, this thesis seeks to answer the following questions: a) What is the transport rate of particles by diffusiophoresis through a self-generated ion gradient especially from dissolving minerals? b) What are the transport and pumping rates in dead-end capillaries due to diffusiophoretic and diffusioosmotic flows from imposed gradients of simple monovalent salts (e.g. NaCl)? c) Can we control transport in dead-end capillaries in mixed ion mineral systems which have more complex diffusion patterns and shuttle changes in zeta potentials? Diffusiophoretic mechanism operates on the basis of spontaneous generation of electric field from an ion-gradient source which generates motion of charged mobile particles and diffuse layer across wall surfaces, creating flows similar to electrophoresis and electroosmosis respectively. It is an auto-electrokinetic mode of transport and fluid flow involving no external electric field in the system. Such flows are shown to occur even in dead-end capillaries which are inaccessible to any other form of fluid flow mechanism. Particle transport through diffusive processes have been studied before in relation with reaction-diffusion in biology and chemistry, Brownian ratchet processes, dispersion in microfluidics and even salt-fingering in ocean mixing. However, by establishment or self-generation of salt gradients, particle migration is shown to be boosted significantly. The novelty in my work comes in through experiments via various ion-gradient generation mechanisms which show that diffusiophoresis can generate flows in capillaries with a dead-end where pressure-driven flows seize to operate. In this work, I show that the essential physics of diffusion-induced fluid flow could be used to generate pumping from calcium carbonate micropumps in microporous geologic systems, which could be further used for extraction of oil plugs entrapped inside dead-end pores of reservoir rocks. An understanding of the morphology of channels, and slip at the walls under extreme conditions of temperature and pressure, would give us a better understanding of the feasibility of diffusiophoresis in actual geological deposits.