Fine ultrafiltration of concentrated oligosaccharide solutions – Hydration and pore size distribution effects

Abstract

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On the presence of solute-solvent transport coupling in reverse osmosis

“…Expanding the left-hand side of Eq. 1 using the expression of d i in terms of the chemical potential gradient [9,10]:…”

“…Assuming that a continuum description of the flow is possible, and due to the small (sub-nanometer) 'pore' size in RO and NF membranes, a laminar flow is considered. This flow can be described by the Hagen-Poiseuille equation, and hence there is a linear pressure profile along the pore [10,11]. The value of this pressure gradient is influenced by the solute concentration inside the membrane [13].…”

“…where D s,l is the reduced diffusivity of the solute in the solvent while traversing the membrane pore, termed in many sources as D s,pore [10,11].…”

“…Finally, the solvent velocity in the stationary reference frame is commonly denoted by J l in literature [10,11]. The solute transport equation by the pore-flow model is thus described by:…”

Performance Evaluation of Tight Ultrafiltration Membrane Systems at Pilot Scale for Agave Fructans Fractionation and Purification

“…However, separation using tight UF membranes (from 1 to 3 kDa) becomes more complex because it combines the sieving effect and Donnan exclusion, like the phenomenon that dominates the nanofiltration process (from 200 Da to 1 kDa). In some cases, the membrane with 1 kDa MWCO is considered a nanofiltration membrane because it is at the cut-off limit and is used for decolorization, phosphate elimination, and the purification of oligosaccharides [ 14 , 20 , 21 , 22 ].…”