Reduction Of Membrane Fouling Using Calcium Carbonate Diffusiophoretic Micropumps

Open Access
Author:
Dani, Nishant Shashi
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Darrell Velegol, Thesis Supervisor
  • Darrell Velegol, Honors Advisor
  • Kyle Jeffrey Magnuson Bishop, Faculty Reader
Keywords:
  • chemical engineering
  • membranes
Abstract:
Membrane systems are becoming an increasingly important method for filtration, but their utility is often compromised by colloidal fouling. While there are a number of studied causes of fouling, one probable source of membrane fouling that has not been studied is fouling due to diffusiophoresis. Diffusiophoresis is a particle transport phenomenon that occurs from the combination of electrophoretic and chemiphoretic forces due to the presence of a transient salt gradient. In this thesis, we establish that diffusiophoresis is a mechanism that affects the colloidal fouling of microdialysis membranes. By recognizing this mechanism, we also see that diffusiophoresis can mitigate or reverse this fouling through the use of calcium carbonate micropumps. The first part of this hypothesis was explored by modelling the motion of particles near the membrane due to diffusiophoresis and comparing these values to the experimental velocities in transient salt gradients within membrane modules. We found that the motion of the particles closely matched the predicted values under diffusiophoretic motion, demonstrating its presence. The second component was supported by placing calcium carbonate micropumps in the setups that had previously shown extensive fouling due to the salt gradient and contrasting the systems with and without the micropumps. The system with the calcium carbonate micropumps showed no accumulation of particles on the membrane wall and an exclusion region, with no particles around the membrane. By recognizing the importance of diffusiophoresis in membrane fouling, and then using this mechanism to mitigate the problem, we aim to improve membrane performance.