| abstract |
A composite membrane comprising a discriminating layer and a porous support layer for the discriminating layer, CHARACTERISED IN THAT the discriminating layer comprises at least 60wt% of oxyethylene groups and the porous support layer has a CO 2 gas flux of 5 to 150 x 10 -5 m 3 (STP)/m 2 .s.kPa at a feed pressure of 2.07kPa. The membranes are particularly useful for purifying waste gas streams e.g. by removing greenhouse gases. |