(553e) Applications of Rate Model Simulations in the Design of Ion Exchange Process

VERSE (VErsatile Reaction SEparation) simulation tool has been developed and tested at Purdue since 1990 for various batch and continuous adsorption, ion exchange, and chromatography separations. VERSE is based on a detailed rate model, which takes into account competitive adsorption or ion exchange, detailed mass transfer mechanisms (axial dispersion, film mass transfer, pore diffusion, or surface diffusion), and some reactions in the mobile phase or in the stationary phase. VERSE can simulate batch chromatography (pulse, frontal, linear gradient elution, stepwise elution, displacement chromatography, and other cyclic operations), carousel, or continuous chromatography (SMB). The adsorbed solute concentrations can be related to the concentrations in solution via multi-component equilibrium isotherms, mass action laws, or kinetic (non-equilibrium) rate equations. If intrinsic parameters (isotherm parameters, intraparticle pore or surface diffusivities, and interparticle / intraparticle void fractions), system parameters (column dimensions, particle size), and operating parameters (flow rates in various zones, port switching time) are given, VERSE can predict the dynamic column profiles and effluent histories of all the solutes in batch or SMB processes. VERSE can be used to understand the competitive adsorption or ion exchange phenomena and the controlling mass transfer rate. It can also be used to explore innovative designs and to reduce experimental effort for process development. This presentation will focus on the fundamental principles and the use of this tool for the design of ion exchange processes for multi-component separations. The dynamics for the removal of ammonium ions in a solution containing Na⁺, K⁺, Ca⁺⁺, and Mg⁺⁺ will be shown to illustrate the propagation of shock waves and diffuse waves in a multi-component system and how intra-particle diffusion affects the wave propagation.