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Cellulose acetate reverse osmosis membranes made by phase inversion method : effects of a shear treatment applied to the casting solution on the membrane structure and performance
Publikationstyp
Journal Article
Date Issued
2011
Sprache
English
Author(s)
Simon, Peter F. W.
Toro, Myrna Aguiar del
Gerstandt, Karen
Volume
46
Issue
3
Start Page
395
End Page
403
Citation
Separation Science and Technology 46 (3): 395-403 (2011)
Publisher DOI
Scopus ID
Publisher
Taylor & Francis
A mixture of equal parts of cellulose diacetate and cellulose triacetate was dissolved in dipropylene glycol and exposed to shear stresses of varying intensity on a three-roll calander. Asymmetric reverse osmosis membranes were prepared from these materials by the phase-inversion method. Reverse osmosis tests in a dead-end module provided membrane performance data. A structure analysis was performed by scanning electron microscopy and the microstructure of the membranes was investigated by differential scanning calorimetry and X-ray diffraction. It was observed that increasing shear times as well as shear rates reduced the salt rejection while the permeate flux was escalating. The size-exclusion chromatography analysis showed a strong decrease of Mw and Mz at a constant Mn indicating the degradation of the higher molar mass macromolecules. Since the physical structure of the membranes was not affected and a change in polymorphism could not be related to the variations in the reverse osmosis performance the reduced salt rejection should be caused by this degradation process, supposedly through affecting the material's diffusion properties by changing the fractional free volume. © Taylor & Francis Group, LLC.
Subjects
Cellulose acetate
Molar mass
Reverse osmosis
Shear stress
Structure analysis
DDC Class
550: Earth Sciences, Geology
570: Life Sciences, Biology
624: Civil Engineering, Environmental Engineering