title: Evaluation and characterization of axial distribution in expanded bed: II. Liquid mixing and local effective axial dispersion.
abstract: Expanded bed adsorption (EBA) is a promising technology to capture proteins directly from unclarified feedstock. In order to better understand liquid mixing along the bed height in expanded beds, an in-bed sampling method was used to measure residence time distribution at different bed heights. A 2cm diameter nozzle column was tested with agarose raw beads (3% crosslinked agarose containing tungsten carbide). Two settled bed heights (11.5 and 23.1cm) with different expansion factors (1.4-2.6) were investigated and the number of theoretical plates (N), the height equivalent of theoretical plate (HETP) and the local effective axial dispersion coefficient (Dax) were calculated for each bed height-defined zone. The effects of expansion factor, settled bed height and mobile phase were evaluated. The results showed that N increased with the increase of expansion factors, but Dax was unaffected under fixed bed heights. Dax and HETP were found similar as a function of relative bed height for two settled bed heights tested. Higher mobile phase viscosity resulted in stronger axial dispersion. In addition, the local effective Dax under the expansion factor near 2.0 had a different profile which showed minimum values at 0.6-0.8 relative bed height, and the potential mechanism was discussed. These results would be useful for the characterization of axial dispersion and modeling protein adsorption in expanded beds under varying operation conditions.
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China. Electronic address: lindq@zju.edu.cn.
authors.forename: Dong-Qiang
authors.initials: DQ
authors.lastname: Lin
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Hong-Fei
authors.initials: HF
authors.lastname: Tong
authors.affiliation: DSM Biotechnology Center, Center of Integrated BioProcessing, Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands. Electronic address: emile.sandt-van-de@dsm.com.
authors.forename: Emile J A X
authors.initials: EJ
authors.lastname: van de Sandt
authors.affiliation: Patheon Biologics, Zuiderweg 72/2, 9744 AP Groningen, The Netherlands.
authors.forename: Piet den
authors.initials: Pd
authors.lastname: Boer
authors.affiliation: DSM Biotechnology Center, Center of Integrated BioProcessing, Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands.
authors.forename: Guilherme N M
authors.initials: GN
authors.lastname: Ferreira
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Shan-Jing
authors.initials: SJ
authors.lastname: Yao
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid / Q000295:instrumentation / Q000379:methods*; D012685:Sepharose; D017973:Tungsten Compounds; D014783:Viscosity
chemical_list: D017973:Tungsten Compounds; C002802:tungsten carbide; D012685:Sepharose
keywords: Axial distribution; Expanded bed adsorption; Liquid mixing; Local effective axial dispersion; Residence time distribution