New test apparatus for measuring particle kinetics and equilibrium isotherms based on a differential column approach


C.E. Duffey, W.D. King, and L.L. Hamm. Savannah River Technology Center, Westinhouse Savannah River Company, Aiken, SC 29808
An understanding of resin performance in a liquid chromatographic column requires that several underlying mass transport mechanisms be quantified. The development of a kinetics test apparatus based on a differential column concept will be presented. This setup allows for the estimation of particle pore diffusion coefficient, particle liquid-film coefficient, and true equilibrium capacities (i.e., sorption isotherm) for a resin. Additionally, the design provides for increased flowrate control and is simple to fabricate. Experimental results for the removal of perrhenate ion (a chemical surrogate for pertechnetate) from a high alkaline, low-level radioactive waste stream simulant generated with the apparatus are shown. Impacts on mass transfer parameters from varying temperature, liquid-phase composition, and particle size are discussed. To demonstrate the composite impact of these mass transfer mechanisms, a column transport model using the experimentally determined parameters is compared to recently measured column behavior. Our experience indicates that this experimental setup provides consistent kinetics and equilibrium data key in the understanding and prediction of column performance.