Cellulose acetate (CA) is well known glassy polymer used in the fabrication of gas-separation membranes. In this study, 5,11,17,23-tetrakis(N-morpholinomethyl)-25,26,27,28-tetrahydroxycalix[4]arene (CL) was blended with CA to study the gaspermeation behavior for CO 2 , N 2 , and CH 4 gases. We prepared the pure CA and CA/CL blended membranes by following a diffusion-induced phase-separation method. Three different concentrations of CL (3, 10, and 30 wt %) were selected for membrane preparation. The CA/CL blended membranes were then characterized via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction analysis. The homogeneous blending of CL and CA was confirmed in the CA/CL blended membranes by both SEM and AFM analysis. In addition to this, the surface roughness of the CA/CL blended membranes also increased with increasing CL concentration. FTIR analysis described the structural modification in the CA polymer after it was blended with CL too. Furthermore, CL improved the tensile strength of the CA membrane appreciably from 0.160 to 1.28 MPa, but this trend was not linear with the increase in the CL concentration. CO 2 , CH 4 , and N 2 gases were used for gas-permeation experiments at 4 bars. With the permeation experiments, we concluded that permeability of N 2 was higher in comparison to those of CO 2 and CH 4 through the CA/CL blended membranes. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39985.

This work evaluates the viability of a two-stage process using combined nitrogen (N 2 )-selective and carbon dioxide (CO 2 )-selective membranes for post-combustion CO 2 capture. A novel type of cellulose acetate (CA) hybrid membrane is used here as a N 2 -selective membrane. The silica functionalized with p-tetranitrocalix[4]arene (Si−CL) was incorporated into the CA matrix, thereby resulting in a CA/Si−CL hybrid membrane. Moreover, the published permeation data of a CO 2 -selective fixed-site-carrier (FSC) membrane, i.e., polyvinylamine (PVAm) casted on porous polysulfone (PSf), is used here in a simulation study to serve as a second stage membrane. Although experimental work on the CA/Si−CL hybrid membrane is in progress based on the assumptions of initial appreciable results, a two-stage membrane process is proposed in which a N 2 -selective membrane is placed in the first stage, while a CO 2 -selective membrane is placed in the second stage. Subsequently, the technoeconomic analysis of a two-stage membrane process has been carried out to evaluate the energy demand and CO 2 capture cost for post-combustion CO 2 capture application. The feasibility analysis shows a slower value of energy consumption (1.0 MJ/kg of CO 2 ) and CO 2 capture cost ($20.5/ton of CO 2 ) by employing N 2 -selective and CO 2 -selective membranes.

Cellulose acetate (CA) is a widely applied glassy polymer in the preparation of gas separation membranes. In the present study, hybrid membranes were prepared by incorporating silica (Si) and silica functionalized with ptetranitrocalix[4]arene (Si-CL) into the CA matrix, and their gas permeation abilities were explored with regard to CO 2 , N 2 and CH 4 gases. The diffusion-induced phase separation (DIPS) method was adopted to make pure CA, CA/Si, and CA/Si-CL hybrid membranes. The concentration of Si-CL was varied as 10 wt%, 20 wt% and 30 wt% in the hybrid membranes. The analytical techniques employed for membrane characterization were Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X ray-diffraction (XRD) analysis. The proper interaction of Si and Si-CL was confirmed by FTIR analysis. However, the homogenous surface textures of CA/Si, and CA/Si-CL hybrid membranes were evaluated through SEM. Furthermore, AFM analysis was performed to examine the surface roughness of these hybrid membranes. The changes in the crystallinity of CA were also examined by XRD analysis after adding Si and Si-CL. Moreover, the tensile strength of the CA/Si hybrid membrane was found to be better than that of CA/Si-CL hybrid membranes. CO 2 , CH 4 and N 2 gases were used for gas permeation experiments at 400 kPa. Among CO 2 and CH 4 gases, the permeability of N 2 was high in CA/Si-CL hybrid membranes, and N 2 /CO 2 selectivity of these membranes was 22.6.