The origin of large pores on aromatic polyamide membrane surfaces
- Univ. of Ottawa, Ontario, (Canada). Dept. of Chemical Engineering
Linear polymer solutions are represented as suspensions of macromolecule spheres. Macromolecules concentrate at the interface during the membrane-making procedure. Permanent contacts are made between adjacent macromolecules. The macromolecules coalesce with each other to some extent, which causes a reduction in the interstitial void areas. The magnitude of an interstitial void is dependent on the size, packing arrangement, and degree of coalescence of the surface macromolecules. During membrane use, permeation occurs only through the interstitial voids in the skin layer. The interstitial void model is applied to some aromatic polyamide solutions and their resultant reverse osmosis/ultrafiltration membranes. The skin layer of such a membrane is composed of a monolayer of predominantly close-packed solution macromolecules that have partially coalesced with each other. Larger pores in the skin monolayer occur if interstitial voids are formed by surrounding by four or more macromolecule spheres. This paper compares casting composition and structure of the larger pores, according to the interstitial void model. The origins and magnitudes of the large pores are determined to be dependent on the casting solution composition and structure and on the membrane-making procedure. The practical utility of the interstitial void model is for design purposes. Membrane performance can be related to the precursor solution composition and/or the membrane-making procedure.
- OSTI ID:
- 5791508
- Journal Information:
- Journal of Colloid and Interface Science; (United States), Vol. 160:1; ISSN 0021-9797
- Country of Publication:
- United States
- Language:
- English
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MEMBRANES
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DESIGN
MATHEMATICAL MODELS
OSMOSIS
POLYAMIDES
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FILTRATION
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ORGANIC COMPOUNDS
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