| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
A new oxygen enriching membrane composed of poly(vinyl alcohol) membrane swollen with aqueous solutions of various nonvolatile substances has been proposed. This study has been developed along the following steps. First, a standard stainless steel apparatus for the gas permeability measurements of water-swollen membranes was constructed. It was confirmed that this apparatus is easy to operate, and gives data within <plus-minus> 10 % deviation. The permeability can be measured under up to 6 atm. It was also confirmed that the permeability of the water-swollen membranes is independent of the upstream pressure. Second, for the membranes swollen to 0.35 - 0.85 of water content with the aqueous solutions of urea, thiourea, lithium chloride, lithium iodide, cesium chloride, tetraethylammonium chloride, sodium tetraphenylborate, hexadecyltrimethylammonium chloride and zinc chloride, the permeabilities of oxygen and nytrogen were measured. It was found that the former three substances enhance
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the permselectivity of O_2 over N_2 to 6 - 15. The permeability of oxygen under these permselectivities ranges 5x10^<-10> - 5x10^<-11>cm^3(STP)cm cm^<-2> s^<-1> cmHg^<-1>. From the time lag measurements of the gas permeation, diffusion coefficients of the gases in the membranes were estimated. The solubilities of the gases were calculated from the permeability and diffusion coefficient data. The addition of the substances effective to the permselectivity lowers the diffusion coefficients but enhances the solubilities especialy at low water contents of the membranes. The high permselectivity is effected mainly by the selective enhancement of the oxygen solubility. Third, the origins of the characteristic variations of the gas diffusion coefficients and solubilities with the water content of the membranes were investigated. A two states model for the water in the membrane was successfully proposed to explain the variations of the diffusion coefficients. The solubility enhancements were accounted for by the presence of structure disturbed water near the polymer chain, which could be detected by the differential canning calorimetry measurements of the crystallization behavior of the water upon cooling. Less
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