(288n) On Determination Procedure of Intraparticle Diffusivity from Multi-Component Chromatogram for Non-Linear Systems

For the design of an adsorption process, kinetic and adsorptive equilibrium parameters are required. For the adsorption of multiple organic compounds using activated carbon in aqueous systems, several useful models have been developed to describe the equilibrium. Myers and Prausnits presented the Ideal Adsorbed Solution (IAS) theory for gaseous phase multi-component adsorption (Myers et al., 1965). Radke and Prausnitz later extended the IAS theory to dilute liquid solutions (Radke et al., 1972). Suzuki applied Freundlich isotherm in IAS theory and developed easy-to-use equations for the estimation of multi-component equilibrium (Suzuki et al., 1983). Finally, Furuya extended Suzuki's model and developed a technique to determine the isotherm parameters from a single composition of multi-component aqueous mixture (Furuya et al., 1986; Sato et al., 2004). Two of the well-known methods for non-linear systems are ?Break Through Curve Technique? and ?Completely Mixed Batch Reactor Technique?. For single adsorption systems, very simple experiments are required in those methods. For multi-component systems, however, the experimental and parameters-determination methods are very complicated. And ?Moment method with Chromatographic Technique? is also excellent method, because the experiments require very small amount of sample liquid. However, this method is valid only for linear adsorption systems, and thereforehas a limited application. Because of simple experimental procedue, chromatographic technique must be useful for determination of intraparticle diffusivities when the procedure can be applied to non-linear systems. Concentration history of most adsorbable component is not affected by diffusivities of other components. This means that the intraparticle diffusivity of each component seems to be obtained in order of adsorbability. In this study, possibility of determing intraparticle diffusivity for non-linear adsorption of multiple components by use of chromatigraphic technique will be discussed. The method was aided by the graphical comparison of experimental data and numerical simulation results.

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