Trial for Preparation of Glass Capillary Membranes by Elution of Alkali Metal Ions

ABSTRACT The gas separation characteristics of ultramicroporous glass capillary membranes were investigated. Glass capillary membranes which had ultramicropores (pore diameter less than 1 nm) were prepared by elution of alkali metal ions from glass capillaries. It was found from elution treatment that alkali metal ions of 3 Na(composition: 778 SiO2, 22 Na2O mol%) and 3 K (composition: 77 SiO2, 22 K2O mol%) glass capillaries were completely eluted after 90 and 10 minutes with 3 mol/L HNO3, 240 and 10 minutes with 3 mol/L CHM3COOH and 3 mol/L H3PO4, respectively. Permeations of N2, He, and CO2 were measured at 298, 373, and 473 K. Permeation rates of the 3 Na and 3 K glass capillary membranes were 11 (cm3(STP).cm2-s1.cmHg1). The ratios of permeation rates, CO2/N2 and He/N2, were similar to the theoretical Knudsen values.