Diffusivity of Xylitol in Granular Activated Charcoal

Abstract

The xylitol adsorption on granular activated charcoal was investigated. From the experimental observations, a non-linear adsorption isotherm of Lamgmuir type equation was used to describe intraparticle diffusivity of xylitol on granular activated charcoal in liquid-phase adsorption. Two langmuir coefficients, Q_max = 0.2191 kg/kg and k = 0.1216 m³/kg were estimated using linear regression analysis. Surface diffusion coefficients (D_s) were determined from adsorption rates in a finite bath using diffusion model. As a result, Ds increased with and increase of initial xylitol concentration (C_L0) or so called an equilibrium amount of xylitol adsorbed on activated charcoal (q_∞). This relation resulted in the following equation, D_s = 0.7911x10^-8 exp(5.849q_∞). In addition, for a packed bed column, a perfect mixing model gave a good fitting with experimental result under the conditions of this investigation. The simulation with perfect mixing model were demonstrated with changes of flow rates and bed lengths. Different saturation time and no breakthrough times were figurely revealed.