Dual mode model for mixed gas permeation of CO₂, H₂, and N₂ through a dry chitosan membrane

• Published in: Journal of polymer science. Part B, Polymer physics Polymer physics, 2007-09, Vol.45 (18), p.2620-2631
• Main Authors: El-Azzami, Louei A, Grulke, Eric A
• Format: Article
• Language: English
• Subjects: activation energies; Applied sciences; chitosan; dry chitosan membrane; dual mode parameters; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; gas permeation; glass transition; glass transition temperature; membranes; mixed gas permeation; Natural polymers; Physicochemistry of polymers; Polymer industry, paints, wood; Starch and polysaccharides; Technology of polymers
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.21236

Dry chitosan is an excellent candidate for facilitated transport membranes that can be utilized in industrial applications, such as fuel cell operations and other purification processes. This article is the first to report temperature effects on transport properties of CO₂, H₂, and N₂ in a gas mixture typical of such applications. At a feed pressure of 1.5 atm, CO₂ permeabilities increased (0.381-26.1 barrers) at temperatures of 20-150 °C with decreasing CO₂/N₂ (19.7-4.55) and CO₂/H₂ (3.14-1.71) separation factors. The pressure effect on solubilities and permeabilities were fitted to the extended dual mode model and its corresponding mixed gas permeation model. The dual mode and transport parameters, the sorption heats and the activation energies of Henry's and Langmuir's regimes and their pre-exponential parameters were determined. The Langmuir's capacity constants were utilized to estimate chitosan's glass transition temperature (CO₂: 172 °C, N₂: 175 °C, and H₂: 171 °C). The activation energies of diffusion in the Henry's law and Langmuir regimes were dependent on the collision diameter of the gases. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2620-2631, 2007