Silica composite membrane was obtained by the repeated dipping method from a 30 nm y-Al2O3 membrane. Gas permeation behaviour was obtained from the gases (N2, CO2, O2, CH4, H2, and He) at a permeation temperature of 298 K and an average pressure between (1.03 - 3.50 Pa). Single gas permeance and permeability of the membrane was calculated in this experiment. This silica composite membrane showed permeability of up to (10-7 - 10-8 mol m/m2 s-1 Pa-1) for the gases (N2, CH4, and H2) after the 5th dip at permeation temperature of 298 K. Gas permeabilities through the silica membrane followed the order of their designated molecular weight written as (H2 > CH4 > N2 > O2) which is (2 > 16 > 28 > 32 g/mol), and attributed to Knudsen flow transport mechanism. The permeance of gas molecules (N2, CO2, O2, H2, He and CH4) on the membrane was also obtained for up to three number of dippings at permeation temperature of 298 K and an average pressure of (1.15 - 1.50 Pa). However, the result shows that gas permeance decreases as the number of dipping increases. The results shows an outstanding regression fit (R2 = 0.9989, 0.9966, 0.9958, 0.9939 and 0.9925) at 2nd dip for the gas molecules (N2, CO2, CH4, H2 and O2) which also confirms Knudsen flow mechanism where the interactions of molecule-pore wall are more significant.

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