Stochastic simulation of separation systems

A three-dimensional stochastic simulation of chromatography has been developed and used to study absorption chromatography, adsorption chromatography, and reactive chromatography. The trajectories of individual molecules are tracked as the processes of absorption, adsorption, chemical reaction, diffusion, electrophoretic migration, and laminar or electroosmotic flow are simulated. The macroscopic and molecular abilities of the simulation are used to study the effects of the radii of the fluid and surface phases, the diffusion coefficients in the fluid and surface phases, and the absorption coefficient on the rate of molecular transfer between the fluid and surface phases. The data collected from the simulation are used to develop an empirical equation relating the parameters listed above to the mass transfer rate constants. The effects of heterogeneous surfaces on absorption systems are also investigated. It is determined that heterogeneities that cause differences in the absorption coefficient result in a system that behaves as a homogeneous system with an absorption coefficient equal to the average absorption coefficient. Differences in the diffusion coefficient and the interfacial barrier to mass transfer cause noticeable changes in the kinetic behavior of the system, but do not affect the long-time or steady-state behavior of the system.; The computer algorithm for the simulation of linear adsorption chromatography is developed and validated. The algorithm is independent of the time increment of the simulation. The adsorption process is treated as a second order reaction between the adsorbate and the surface, and desorption is treated as a first-order reaction. The kinetic and steady-state behavior of adsorption systems are investigated and the simulation is shown to be in good agreement with established theories of adsorption chromatography.; Finally, systems in which reaction and separation occur concurrently (reactive separations) are considered. The responses of reactive separation systems with irreversible and reversible reactions to changes in the absorption coefficient, the diffusion coefficient, and the reaction rate are studied. The statistical moments of the reactant and product zones are shown to be in agreement with established theories. The data also suggests that the mass transfer and reaction rates affect the system response in a dependent manner. The data show that separation of the reactant and product species is possible while the system is not at steady state. The yield and purity of the product is shown to increase for systems in which the absorption coefficient of the product is smaller than the absorption coefficient of the reactant. (Abstract shortened by UMI.)...