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 - Jan 1 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

  • Chemical Engineering(all)

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, 01.01.1998, 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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