Selectivity sorption and permeation of molecular oxygen are described for 2-methylacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester cobalt(II) coordinated with rubbery copolymer membranes. Rubbery copolymers with different highly chelating group contents are prepared by using soap-free emulsion copolymerization. Amounts of cobalt(II) ion adsorbed by the rubbery copolymer membranes are in the range of 0.7-2.0wt.%, in other words, cobalt(II)-complex contents in membranes are up to ca. 12wt.%. The cobalt(II)-complex in membranes is a kind of highly oxygen-affinity material as well as rapid and reversible oxygen adsorption/desorption behavior showing. IR results of the oxygen-binding cobalt(II)-complexes show evidence for formation of mononuclear superoxo complexes. Sorption isotherms of oxygen for the membranes are analyzed with a dual-mode sorption model to give CC′ (the saturated amount of oxygen reversibly bound to the cobalt(II) sorption site) and K (the oxygen-affinity constant of cobalt(II)-complex). The oxygen permeability of the membrane containing cobalt(II)-complex increased with decreasing upstream oxygen pressure, which is in accordance with a dual-mode transport model. Moreover, the oxygen permeability/selectivity combinations are above and to the right of the "upper bound" line as the cobalt(II) contained as much as 1.7wt.% (cobalt(II)-complex 12.3wt.%) in membrane under high upstream oxygen pressure (Pu≤2atm), however, the best oxygen permeability and selectivity combinations in this study are as high as 11.2/10.3 under Pu=0.5atm, respectively.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry
- Filtration and Separation