Composite membranes were prepared for separation of ethylene from nitrogen using polyethersulfone (PES) as support and polydimethylsiloxane (PDMS-a grade of silicone rubber) as active layer at various concentrations. Permeance and ideal selectivity were measured for all membranes under the transmembrane pressure of 2 to 6 bars. Influences of affecting parameters on membrane performance (i.e. permeance and selectivity) were investigated. The studied parameters include: PES concentration in casting solution, solvent type, PDMS concentration in coating layer, support thickness, coating thickness and coagulation atmosphere. For all coated membranes, the ethylene permeance was higher compared to the nitrogen permeance except for 5% coated air coagulated membrane. This membrane was more permeable for N2 in comparison with ethylene under the pressures higher than 2 bars. The nitrogen permeance exhibited a rather constant value. There was no significant change in nitrogen permeance with respect to the coating layer, whereas ethylene permeance was highly influenced by coating layer composition and support thickness. The governing mechanism for the separation is solution-diffusion of ethylene in PDMS layer (solution-diffusion model). The SEM study was carried out for investigation of membrane morphology. In a run ethylene was passed through the membrane after the passage of nitrogen. In the second run ethylene was passed through the membrane before nitrogen. The nitrogen selectivity was reduced in the later test. This is due to the ethylene high solubility in membrane matrix.
Membrane Composite Polydimethylsiloxane Polyethersulfone Gas separation Ethylene Nitrogen
This is a preview of subscription content, log in to check access
Wu P, Brisdon BJ, England R, Field RW (2002) Preparation of modified difunctional PDMS membranes and a comparative evaluation of their performance for the pervaporative recovery of p-cresol from aqueous solution. J Membr Sci 206:265–275 doi:10.1016/S0376-7388(01)00774-8CrossRefGoogle Scholar
Nunes SP, Peinemann KV (2001) “Membrane technology in the chemical industry”. Wiley-VCH, Weinheim, GermanyGoogle Scholar
Shieh J-J, Chung T-S (1999) Phase-Inversion Poly(etherimide) membranes prepared from water-miscible/immiscible mixture solvents. Ind Eng Chem Res 38:2650–2658 doi:10.1021/ie9807912CrossRefGoogle Scholar
Morton M (1987) “Rubber Technology”. Van Nostrand Reinhold, New YorkGoogle Scholar