The effects of electrostatic interactions on the rejection of colloids by membrane pores-visualisation and quantification

W. Richard Bowen, Nidal Hilal, Mohit Jain, Robert W. Lovitt, Adel O. Sharif, Chris J. Wright

    Research output: Contribution to journalArticle

    Abstract

    The pressure driven membrane processes of microfiltration and ultrafiltration are usually classified in terms of the size of solutes (colloids) separated. However, theoretical calculations have shown that electrostatic double-layer interactions can have a strong influence on rejection at the pores of such membranes. The present paper provides experimental evidence to support these findings. Firstly, atomic force microscopy in conjunction with the colloid probe technique is used to measure directly the repulsive electrostatic force experienced when a single colloidal particle approaches a microfiltration membrane. Scanning of such a membrane with the colloid probe provides a direct visualisation of the membrane surface as would be experienced by a colloidal particle during filtration. Secondly, filtration flux/time data is presented for the case of filtration of particles of size very close to the pore size in an ultrafiltration membrane. For such a case, theoretical calculations allow definition of a critical pressure at which the hydrodynamic force transporting the colloid toward the membrane pore is exactly balanced by the opposing electrostatic force. The experiments show that operating above this pressure results in a rapid loss in filtration flux, but operation below this pressure allows continuing filtration with only a minor decrease in flux, in agreement with the calculations.

    Original languageEnglish (US)
    Pages (from-to)369-375
    Number of pages7
    JournalChemical Engineering Science
    Volume54
    Issue number3
    DOIs
    StatePublished - Dec 4 1998

    Fingerprint

    Colloids
    Coulomb interactions
    Visualization
    Membranes
    Microfiltration
    Electrostatic force
    Ultrafiltration
    Fluxes
    Pore size
    Electrostatics
    Atomic force microscopy
    Hydrodynamics
    Scanning

    Keywords

    • Atomic force microscopy
    • Colloid probe
    • Critical pressure
    • Membrane
    • Microfiltration
    • Ultrafiltration

    ASJC Scopus subject areas

    • Chemistry(all)
    • Chemical Engineering(all)
    • Industrial and Manufacturing Engineering

    Cite this

    The effects of electrostatic interactions on the rejection of colloids by membrane pores-visualisation and quantification. / Bowen, W. Richard; Hilal, Nidal; Jain, Mohit; Lovitt, Robert W.; Sharif, Adel O.; Wright, Chris J.

    In: Chemical Engineering Science, Vol. 54, No. 3, 04.12.1998, p. 369-375.

    Research output: Contribution to journalArticle

    Bowen, W. Richard ; Hilal, Nidal ; Jain, Mohit ; Lovitt, Robert W. ; Sharif, Adel O. ; Wright, Chris J. / The effects of electrostatic interactions on the rejection of colloids by membrane pores-visualisation and quantification. In: Chemical Engineering Science. 1998 ; Vol. 54, No. 3. pp. 369-375.
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