Enhancement of protein precipitate strength and density by low-frequency conditioning |
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Authors: | Dr N J Titchener-Hooker Dr R V McIntosh |
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Institution: | (1) Advanced Centre for Biochemical Engineering Department of Chemical and Biochemical Engineering, University College London, Torrington Place, WC1E 7JE London, UK;(2) Scottish National Blood Transfusion Service, Protein Fractionation Centre, Ellen's Glen Road, EH17 7QT Edinburgh, UK |
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Abstract: | The use of a continuous, low-frequency conditioning process to alter the structure of protein precipitate aggregates is examined. An increase in the density of aggregates is correlated with the levels of fluid acceleration and hence hydrodynamic stress to which the aggregates are exposed during conditioning. A combination of low-frequency conditioning followed by shear break-up (as in the feed zone to a high-speed disk-stack centrifuge) is shown to result in a precipitate suspension of increased particle size at the fine end of the distribution, and having a greater sedimentation velocity. The resistance of large aggregates to shear disruption is increased by low-frequency conditioning.List of Symbols
CR
conditioning ratio
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CRS
conditioning ratio after shearing
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d m
amplitude of displacement
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D m
particle size
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D
c m
critical size for centrifuge recovery
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f s–1
frequency of vibration
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G s–1
mean velocity gradient
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Q m3/s
volumetric throughput
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SR
shear ratio
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t s
ageing time
Greek Symbols
s–1
mass-average shear rate
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K
sedimentation shape factor
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a kg/m3
aggregate density
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f kg/m3
fluid density
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s kg/m3
solids density
- ![Delta](/content/t0821l56v87h6761/xxlarge916.gif) kg/m3
aggregate-suspension density difference
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Ns/m2
kinematic viscosity
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amplitude of pulse ratio (ref. 23, 9)
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s
mean residence time
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s
solids volume fraction |
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Keywords: | |
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