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Carbon dioxide emissions to the atmosphere lead to global warming and unpredictable climate change via the greenhouse effect. Carbon dioxide from industrial sources can be captured by the membrane separation technique to mitigate the greenhouse effect. In this research, a polymer solution was prepared by blending a cellulose triacetate (CTA) polymer with a tri‐n‐butyl phosphate (TBP) additive. The polymer solution was coated on an alumina (α‐Al2O3) tube, which acted as a support material, to prepare a composite membrane for the CO2 separation. The composite membrane that was prepared was characterized by Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermo‐gravimetric analysis (TGA), and differential scanning calorimetry (DSC) analyses. The CO2 permeance and the selectivity for the prepared composite membrane were evaluated using a constant pressure‐variable volume method. The influence of the concentration of CTA and TBP, polymer solution preparation time, number of sequential dip coating, and the feed gas pressure on the CO2, N2, and CH4 gas separation performances was examined. The highest CO2 permeance of 129 GPU and the selectivity of 19.9 versus N2 and 10.6 against CH4 were obtained for the pure gases, and a CO2 permeance of 116 GPU and selectivity of 17.1 against N2 were obtained for a mixture of gases (15% CO2/85% N2). © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Carbon sequestration and utilization are currently gaining attention as they help to reduce the emission of greenhouse gases in the atmosphere. This study explores the possibility of using carbon dioxide as a feedstock for the production of ammonium carbamate, a precursor molecule for urea production. Waste cooking oil was used as the indispensable nonaqueous medium for the formation of pure ammonium carbamate. This makes the process completely ecofriendly and cost-effective. A continuous process of ammonium carbamate production at 20°C results in 88.86% consumption of carbon dioxide. The highest yield of ammonium carbamate was achieved at an NH 3 /CO 2 ratio of 2.5. A three-stage setup was also found to increase the yield of ammonium carbamate. The reusability of oil after each cycle was checked and it was found that the formation of the product is comparatively less compared to the previous cycle. Lower yield was observed when the same experiment was carried out with fresh oil (sunflower oil). The exit gas from the process was found to be rich in ammonia that can be further used for the production of struvite, a phosphate fertilizer.

The gas transport property of the hydrogel chitosan (CS) and the CS-polyethylene glycol (CS+PEG) polymer blend surface-modified polyvinyltrimethylsilane (PVTMS) composite membranes have been evaluated for pure CO 2 , N 2 , and CH 4 gases. The physic-chemical characteristics and the surface morphological features of the prepared pure and the composite PVTMS membranes were interrogated with the Fourier transform infrared spectroscope, high-resolution scanning electron microscope, thermogravimetric analysis, and differential scanning calorimeter. Effect of water wetting of the membrane, number of sequential coating, and the transmembrane pressure on the gas transport properties of the pure and composite PVTMS membranes was concurrently studied. The acceptable CO 2 permeability of 153 barrer and the gas-pair CO 2 /N 2 selectivity of 33 and the CO 2 /CH 4 selectivity of 23 were obtained for the CS+PEG-modified PVTMS membrane under the optimum conditions, that is, transmembrane pressure of 76 cmHg and the reaction temperature of 30 C. The CO 2 separation performance of the modified PVTMS composite membrane against the N 2 and the CH 4 gases moved close to Robeson's upper bound 2008. Enhancement in the CO 2 separation efficacy of the modified PVTMS membrane than the pure PVTMS membrane has proved good efficiency of the modified membrane towards CO 2 capture application.