Abstract
The separation and recovery process of organic acids from fermentation process, sub-critical water hydrolysis process, and other industrial processes by using a highly porous PEI chitosan beads (hereafter called PEI-Ch) as adsorbent was developed. Three different organic acids: acetic acid, formic acid, and pyroglutamic acid were considered.
First, the adsorption isotherms were investigated. The organic acids were highly adsorbed on PEI-Ch. A theoretical equation for adsorption isotherm was derived based on the mass-action law by considering the adsorption of organic acids on the four different functional amino groups of PEI-Ch. A good correlation was obtained between the experimental data and the proposed theoretical model.
Second, the intraparticle diffusions of organic acids in PEI-Ch were investigated by the shallow bed method. The experimental uptake data were correlated by applying the homogeneous Fickian diffusion model and the parallel diffusion model for surface and pore diffusions. In all experimental systems, the values of the effective intraparticle diffusivity obtained from the homogeneous model increased with increasing the bulk-phase concentration of organic acids, and suggested an existence of a parallel transport of organic acids in the particle by surface and pore diffusions. The parallel diffusion model agreed reasonably well with the experimental data.
