Determining particle density distribution of expanded bed adsorbents.

Area of Science:

• Biochemical Engineering
• Separation Science
• Materials Characterization

Background:

• Expanded bed adsorption (EBA) is crucial for protein purification.
• Accurate characterization of EBA matrix properties is essential for process optimization.
• Previous hydrodynamic models often assume uniform bead density, which may not reflect reality.

Purpose of the Study:

• To experimentally determine the density distribution of EBA matrices.
• To investigate the relationship between bead density and particle size.
• To assess the impact of density variation on settling velocity calculations for hydrodynamic modeling.

Main Methods:

• Utilized caesium trifluoroacetate (CsTFA) solutions of varying densities in a centrifuge to separate EBA matrix samples by bead density.
• Employed mass measurements to plot decumulative density distributions.
• Applied laser light scattering to determine particle size variation with density.
• Calculated particle settling velocity distributions based on experimental data.

Main Results:

• Established a reliable method for characterizing EBA matrix density distribution.
• Found that particle size distribution remained constant across varying bead densities for Streamline matrices.
• Determined bead densities ranging from 1.5 to 2.1 g/cm³ in CsTFA, translating to 1.11-1.33 g/cm³ in aqueous buffer.
• Demonstrated that settling velocity distributions calculated using measured density distributions were insignificantly different from those using an assumed mean density.

Conclusions:

• The developed method provides a simple and reliable characterization of EBA matrix density.
• Experimental results validate the assumption of a single, constant mean density for EBA particles in hydrodynamic modeling.
• This finding supports the use of simplified models for predicting EBA process performance.