A 0.1-um thick, low-density polyethylene membrane with prop- erties given in Table 14.6 is to separate 37,000 m' (at 25 C, 1 atm) /h of air (79 mol% N,, 21 mol% O, ) into enriched O, (A) and enriched N2 (B). The pressure on the feed-retentate side of the membrane is constant at 10 atm. The pressure on the permeate side is constant at 1 atm. Assume perfect mixing on both sides of the membrane and neglect the mass-transfer resistances in the gases on both sides of the membrane. Calculate the membrane surface area required and the mole-fraction compositions of the retentate and permeate for a cut fraction, 0, of 0.4