(449bw) The Determination Method of Intraparticle Diffusivity By Using Circulating Type Shallow Bed Adsorber

Adsorption is used in various fields owing to high selectivity to a certain substance in gas and liquid phase, and the technique is important for separation in chemical engineering. For design of adsorbers, kinetic and equilibrium parameters are required. The kinetic parameters consist of fluid film mass transfer coefficient (k_F) and intraparticle diffusivity (D_S). To determine D_S, Fixed-bed breakthrough curve method, shallow bed method, the completely mixed batch reactor (CMBR) method and the circulating type fixed bed adsorber (CFBA) method are employed. Fujiki et al. proposed a determination method of D_S and k_F from liquid phase fixed bed breakthrough curve. But it is difficult to analyse experimental concentration profile by use of the fixed bed breakthrough curve. CMBR method is a convenient and environmental friendly experimental technique, because 1~2 L volume of test solution is required and the values of DS and kF can be obtained from one concentration decay curve. However, since fixed bed is generally used in chemical industrial separation, the determination of D_S by using fixed bed is preferred.

It was found by numerical calculation that the concentration history obtained by CFBA method was similar to that by CMBR method, when contact time was 5.00~28.0 sec. So the circulating type shallow bed adsorber (CSBA) method is focused on in this study. This method has the advantage of simple and low costs procedure. Furthermore, the value of D_S and k_F can be determined from one concentration history. Both values were determined by comparing concentration experimentally obtained with theoretical curve. As a result, the values of D_S and k_F were similar to those reported previously using CMBR and CFBA. The results indicate that the accurate values of D_S and k_Fare simply determined by the circulating type shallow bed adsorber.