Permeate Flux in Ultrafiltration Processes—Understandings and Misunderstandings

Field, Robert and Wu, Jun Jie (2022) Permeate Flux in Ultrafiltration Processes—Understandings and Misunderstandings. Membranes, 12 (2). p. 187. ISSN 2077-0375

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Concentration polarization refers to the rapid emergence of concentration gradients at a membrane/solution interface resulting from selective transfer through the membrane. It is distinguishable from fouling in at least two ways: (1) the state of the molecules involved (in solution for concentration polarization, although no longer in solution for fouling); and (2) by the timescale, normally less than a minute for concentration polarization, although generally at least two or more orders of magnitude more for fouling. Thus the phenomenon of flux decline occurring over a timescale of tens of minutes should not be attributed to concentration polarization establishing itself. This distinction and a number of questions surrounding modelling are addressed and clarified. There are two paradigmatic approaches for modelling flux, one uses the overall driving force (in which case allowance for osmotic effects are expressed as additional resistances) and the other uses the net driving force across the separating layer or fouled separating layer, although often the two are unfortunately comingled. In the discussion of flux decline models’ robust approaches for the determination of flux-time relationships, including the integral method of fouling analysis, are discussed and various concepts clarified. The final section emphases that for design purposes, pilot plant data are vital.

Item Type: Article
Additional Information: Funding information: J.J.W. is grateful to EPSRC and Durham University for an EPSRC Impact Acceleration Account (IAA) strategic award.
Uncontrolled Keywords: concentration polarization, osmotic model, fouling, modes of fouling, design
Subjects: H300 Mechanical Engineering
H900 Others in Engineering
Department: Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User: Rachel Branson
Date Deposited: 17 Feb 2022 11:08
Last Modified: 17 Feb 2022 11:15

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