2024 AIChE Annual Meeting

(383ab) Fabrication and Scaleup of a Radial CO2 initiated Diffusiophoretic Colloid Separation System

Authors

Esai Lopez - Presenter, Worcester Polytechnic Institute
Elizabeth Stewart, Worcester Polytechnic Institute
Andrew Teixeira, Worcester Polytechnic Institute
Diffusiophoresis is movement induced by the diffusion of ions. The dissolution of CO2 in water yields positive and negative ions with varying diffusivities. In a diffusiophoretic environment the diffusiophoretic velocity is a function of a colloid’s physical properties and a natural logarithmic strength of the developed ion gradient. Diffusiophoresis has been used in planar chips to sort and remove colloids. In the designed concentric tube-in-tube separator, dissolution takes place in a 38 µm radial annulus. This yields an ion gradient in a narrow region. By inducing an ion gradient, a diffusiophoretic environment is established, capable of directing the movement of 0.5 µm negatively charged polystyrene colloids. A rigorous computational fluid mechanics model was developed to demonstrate the ability of low pressure, 150-250 kPa, CO2 to form the necessary charge gradients. Compared to traditional chip designs, particles within the diffusiophoretic separator have faster diffusiophoretic velocities. Bench scale experiments using a custom concentric Teflon AF-2400 tubular diffusiophoretic separator have been conducted and demonstrate a 99% purification of the inlet stream as well as more than 90% recoverable CO2. This work has the potential to be used in the continuous separation of colloidal particles in bio-pharmaceuticals, quantum dots, and crystallization processes.