Cellulose nitrate (CN)-based composite hollow fiber membranes are prepared
for gas separation, The membrane performance is studied in terms of the con
centration of CN coating solution, polysulfone (PS) substrate, pre-wetting
treatment, solvent used in CN solution, and the various substrate materials
. In order to fabricate a useful multilayer composite membrane, the surface
porosity of composite hollow fiber has to be reduced to a certain degree,
before silicone rubber coating, by adjusting the CN coated layer and the PS
substrate structure. The effect of pre-wetting treatment on the membrane p
erformance is found to be minor, which may be due to the coating technique
and the relatively highly permeable substrate used in this study. The solve
nt used in dissolving CN also affects the gas permselective property of the
multilayer composite membranes and this effect may be attributed to the fo
rmation of different membrane morphology of CN layer caused by the differen
t physical properties of solvents. The selection of substrate materials is
important and this work suggests that a permeable material is more suitable
to serve as the substrate. Besides, the substructure resistance in the sub
strate should be kept as low as possible in order not to deteriorate membra
ne performance of the resultant multilayer composite hollow fiber membranes
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