The influence of particle size distribution and operating conditions on the adsorption performance in fluidized beds

• Published in: Biotechnology and bioengineering Vol. 55; no. 1; pp. 54 - 64
• Main Authors: Karau, A., Benken, C., Thömmes, J., Kula, M.-R.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 05.07.1997; Wiley
• Subjects: bed height; Biological and medical sciences; Biotechnology; dispersion; fluidized-bed adsorption; frontal adsorption; Fundamental and applied biological sciences. Psychology; mass transport; Methods. Procedures. Technologies; Others; particle diameter; Various methods and equipments; Proteins; Separation method; Particle size; Purification; Adsorption; Ion exchanger; Serum albumin; Diffusion coefficient; Dispersion; Mass transfer; Fluidized bed
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/(SICI)1097-0290(19970705)55:1<54::AID-BIT7>3.0.CO;2-W

The influence of matrix properties and operating conditions on the performance in fluidized‐bed adsorption has been studied using Streamline diethyl‐aminoethyl (DEAE), an ion exchange matrix based on quartz‐weighted agarose, and bovine serum albumin (BSA) as a model protein. Three different particle size fractions (120–160 μm, 120–300 μm, and 250–300 μm) were investigated. Dispersion in the liquid phase was reduced when particles with a wide size distribution were fluidized compared to narrow particle size distributions. When the mean particle diameter was reduced, the breakthrough capacities during frontal adsorption were enlarged due to a shorter diffusion path length within the matrix. At small particle diameters the effect of film mass transfer became more relevant to the adsorption performance in comparison to larger particles. Therefore matrices designed for fluidized‐bed adsorption should have small particle diameter and increased mean particle density to ensure small diffusion path length in the particle and a high interstitial velocity to improve film mass transfer. Studies on the influence of sedimented matrix height on axial mixing showed an increased Bodenstein number with increasing bed length. Higher breakthrough capacities were also found for longer adsorbent beds due to reduced dispersion and improved fluid and particle side mass transfer. With increasing bed height the influence of flow rate on breakthrough capacity was reduced. For a settled bed height of 50 cm breakthrough capacities of 80% of the equilibrium capacity for flow rates varying from 3 to 9 cm/min could be achieved. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 54–64, 1997.