Composite membranes ideal separation factor

Table 1. Permeability of polymers and ideal separation factors for composite hollow fiber membranes (20 °C).

O in the feed air is equal 10 0.21. Using the ideal separation factor for polycarbonate from Fig. 20.2-8 with a value of pt/p2 = 0.33, a product gas composition of Jo, = 0.38 results rather than the For = 0.30 obtained with the copolymer membrane used by Ward. Clearly, since the oxygen production has been assumed to be the same, the total product flow rate will amonnt to only (0,30/0,38) 10 x 10s SCFD or 7.9 x 10s SCFD of 38% 07 product gas. This higher purity product is mote valuable than the 30% product achievable with the siltcone-polycarbonate membranes at the same value of pjp7-... 

Alternatively, a method entailing surface coating with an alcohol solution of 60% B rank phenol formaldehyde resin (PFR) and dispersant, followed by recarbonization (700°C, 60 min), was used to prepare carbon-carbon composite membranes with improved separation performance by Liang and co-workers [80], On the carbon-caibon composite membrane coated with PFR alcohol solution and added dispersant, the gas permeation rates decreased by a factor of 10, and the ideal separation factor increased, probably due to the PFR s dispersing effect. 

The ideal separation factor, at, between two species 1 and j being separated through a composite membrane having two layers, 1 and 2 (Figure 6.3.35(a)), is... 

Since the ideal separation factor for polysulfone is (1.2 x 10 5/3 X 10 11) 40, and that for silicone is 2.08, this composite membrane behaves more like the polysulfone membrane. 

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