The effect of column verticality on separation efficiency in expanded bed adsorption

Area of Science:

• Biochemical Engineering
• Separation Science
• Chromatography

Background:

• Expanded bed adsorption (EBA) is crucial for direct protein purification from unclarified feedstocks.
• Column geometry and alignment are critical factors influencing fluid dynamics and separation performance.
• Understanding the impact of minor deviations from verticality is essential for optimizing EBA processes.

Purpose of the Study:

• To investigate the effect of column verticality on liquid dispersion and separation efficiency in expanded bed adsorption (EBA) columns.
• To quantify the impact of minor column misalignments on adsorption performance.
• To determine the scale-dependency of verticality effects in EBA.

Main Methods:

• Experiments were conducted using 1 cm and 5 cm diameter columns packed with chromatographic resins.
• Column misalignment was precisely controlled and varied from 0 to 0.185 degrees.
• Liquid dispersion was quantified by measuring the Bodenstein number.
• Separation efficiency was assessed using breakthrough profiles of bovine serum albumin and glucose-6-phosphate dehydrogenase (G6PDH).

Main Results:

• A misalignment of only 0.15 degrees significantly reduced the Bodenstein number (a measure of dispersion) in both 1 cm and 5 cm columns.
• In a 1 cm column, verticality improved protein loading capacity by 7.8% at 10% breakthrough.
• For G6PDH purification in a 1 cm column, a 0.185-degree misalignment reduced loading capacity by 55% compared to a vertical column.
• In the 5 cm column, G6PDH breakthrough profiles were similar for vertical and slightly misaligned (0.15 degrees) configurations.

Conclusions:

• Even minute deviations from column verticality can substantially increase liquid dispersion and decrease separation efficiency in EBA.
• The negative impact of misalignment is more pronounced in smaller diameter columns.
• Maintaining strict verticality is critical for optimizing EBA process performance, particularly at laboratory and pilot scales.