Membrane Gas Separation

13.4
Conclusions 
Extruded fi lms of different Pebax ® grades and dense membranes made by solution blend-
ing of Pebax ® 1657 grade and poly(ethylene glycol) (PEG) or poly(ethylene oxide - co -
epichlorhydrine) (PEGEPI) were characterized by DSC, optical and atomic 
- 
force 
microscopies and gas permeation. The structure – property relationship of the fi lms was 
analyzed. The membrane permeability appears to depend not only on the content of polar 
groups of the Pebax ® grade, but also on the Pebax ® phase structure, which is governed 
by the length of the polyamide and polyether blocks. The Pebax ® 1657 grade offered the 
best compromise in CO 
2
permeation properties, with a CO 
2
permeability of 100 Barrer, 
and an ideal selectivity for CO 
2
relative to nitrogen  
α
 
CO2/N2
of 50. Our best membrane for 
global warming reduction was the one obtained by blending 20 wt.% of PEG 300 and 
Pebax ® 1657 grade; it exhibited a CO 
2
permeability of 128 Barrer, and an ideal selectivity 
 
α
 
CO2/N2
of 80; these performances rank the material among the best membranes for CO 
2
abatement from air sources like fl ue gases. Finally, a 40% enhancement in CO 
2
permeabil-
ity of a dense Pebax ® 1657 membrane obtained by surface modifi cation by cold plasma -
activated nitrogen and hydrogen suggests that the plasma - assisted surface modifi cation 
in order to graft CO 
2
capturing amine groups is a promising technique to improve further 
the performances of a dense membrane.
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Membrane Gas Separation
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