(40e) Modeling Ion Exchange Kinetics for Molecular Imprinted Polymer

Molecular imprinted polymers (MIPs) have the potential to reduce the process steps needed to extract gold, and should demonstrate that the same core bead technology could be extended to other metals and toxic substances that are extracted as byproducts of gold mining. These extensions should show significant reductions in tailing waste products and a significant reduction in environmental impact of mining. Ion exchange resins or activated charcoal are the most commonly used media for separation and sequestration of metal ions from solution. Molecularly imprinted polymer (MIP) beads have been shown to improve rates of separation and selectivity when compared to existing ion exchange resin solutions because they are made of more stable polymers and can be used multiple times. Integrating mathematical models with experimental data can aid in predicting the separation efficiency of an individual MIP bead and optimize the extraction process. Here we will present a mathematical model that describes limiting cases for the kinetics of a particle diffusion controlled ion exchange process, and compare it to elution data by varying the mobilities, (ratio of the diffusivities between counter ions), between spherical ion exchanger. The calculations are based on the nonlinear Nernst-Planck equations of ionic motion, which take into account the effect of the electric forces within the system. Solutions to the equations were obtained using finite difference techniques, and compared with elution data and found that using a mobility ratio of 1 gave the best fit to the data, which implies that the diffusivities of species A and B are roughly equal to one another.