Film-pore diffusion model for the fixed-bed sorption of copper and cadmium ions onto bone char.

The economic advantages of continuous processing of biopharmaceuticals, which include smaller equipment and faster, efficient processes, have increased interest in this technology over the past decade. Continuous processes can also improve quality assurance and enable greater controllability, consistent with the quality initiatives of the FDA. Here, we discuss different continuous multi-column chromatography processes. Differences in the capture and polishing steps result in two different types of continuous processes that employ counter-current column movement. Continuous-capture processes are associated with increased productivity per cycle and decreased buffer consumption, whereas the typical purity-yield trade-off of classical batch chromatography can be surmounted by continuous processes for polishing applications. In the context of continuous manufacturing, different but complementary chromatographic columns or devices are typically combined to improve overall process performance and avoid unnecessary product storage. In the following, these various processes, their performances compared with batch processing and resulting product quality are discussed based on a review of the literature. Based on various examples of applications, primarily monoclonal antibody production processes, conclusions are drawn about the future of these continuous-manufacturing technologies.

Continuous counter-current chromatography for capture and polishing steps in biopharmaceutical production

This paper reports the adsorption of two dyestuffs from aqueous solutions onto bagasse pith studied using an agitated batch adsorber. A three-resistance mass transfer model, based on external mass transport, macropore diffusion, and micropore diffusion, was used to predict concentration versus time decay curves. The predicted curves were correlated with experimental data for up to 24 hours in order to determine the three mass transport parameters.

Three-resistance transport model for dye adsorption onto bagasse pith

The adsorption of two acid dyes, viz. Acid Red AR114 and Acid Blue AB25, on to bagasse pith, a waste material from the sugar cane industry, has been studied. Equilibrium isotherms and agitated batc...

Adsorption Model for the Removal of Acid Dyes from Effluent by Bagasse Pith Using a Simplified Isotherm

The adsorption of Acid Blue 25, Basic Blue 69, Basic Orange 2, and Disperse Blue 7, on peat has been studied using a series of batch adsorption runs. A model has been developed based on external mass transfer and internal diffusion to explain the concentration decay curves. Two system variables, namely, adsorbate concentration and adsorbent concentration, have been studied. The paper presents a rapid analytical solution for predicting the concentration decay curve in batch adsorbers using peat as a cheap adsorbent to remove various classes of dyestuffs from aqueous solution.



The analytical solution depends on the assumption of a psdeudo-irreversible isotherm and that the internal diffusion process occurs via a pore diffusion mechanism. External mass transfer coefficients and internal diffusivities have been estimated for the various systems.



On a etudie l'adsorption sur la tourbe des colorants suivants: Acid Blue 25, Basic Blue 69, Basic Orange 2 et Disperse Blue 7, dans une serie d'operations d'adsorption discontinue. Pour expliquer les courbes de decroissance de la concentration, on a developpe un modele pour le transfert de masse externe et la diffusion interne. On a etudie deux variables, a savoir la concentration de l'adsorbat et celle de l'adsorbant. On presente une solution analytique rapide pour prevoir la courbe de decroissance de la concentration dans les adsorbeurs discontinus, en employant la tourbe comme un adsorbant peu coǔteux pour enlever differentes classes de colorants d'une solution aqueuse.



La solution analytique depend de l'hypothese d'une isotherme pseudo-irreversible et d'un processus de diffusion interne par diffusion dans les pores. On a evalue, pour les differents systemes, les coefficients de transfert de masse externe et les diffusivites internes.

U.Gunnar Svedberg

Papers

Numerical solution of multicolumn adsorption processes under periodic countercurrent operation