Search

The separation of CO2 from flue gases presents a crucial challenge that needs to be addressed. However, membrane processes offer a promising alternative solution. Polysulfone (PSF)membranes were prepared using N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) using a dry–wet phase inversion technique. The membranes were fabricated with the selection of casting parameters, PSF concentration (20–30 wt%), solvent ratio of THF/NMP (0/100–35/65), and evaporation time (0–4 min). In this work, the interaction between these influencing factors during preparation and membrane performance was studied. Scanning electron microscopy (SEM) was used to characterize the membranes for morphological investigation. Taguchi statistical analysis was employed in the Minitab-19 software used for the design of the experiments in this study, and the responses of the CO2 permeance and CO2/N2 separation factor were analyzed and optimized based on the casting parameters. The results showed the CO2 permeance of the membranes was determined between 1.25 ± 0.04 and 8.47 ± 0.51GPU and selectivity was between 2.95 and 8.92.The statistical analysis indicated that casting conditions affect membrane performance in the following order: PSF concentration > solvent ratio > evaporation time. The optimum parameters for casting solution were the PSF concentration of 20 wt%, THF/NMP ratio of 17.5/82.5, and evaporation time of 4 min. The selected method also reinforces the connection between membrane casting parameters and the observed outcomes in terms of permeation and morphology.

Lignin is recommended to a tempting alternative precursor of petroleum for fabricating carbon nanofibers (CNFs) due to its high carbon content, low-cost and renewable resources. However, the property of lignin-based carbon nanofibers (LCNFs) is inferior owing to the heterogeneity and 3D-network structure of lignin, which hinders its application in supercapacitors. The latest developments in fractionation technology have shown great potential for overcoming the aforementioned shortcomings. However, most of fractionation methods mainly rely on expensive chemicals and complex reaction process, such as enzymes, multiple solvents, membranes, and dialysis tubes. Herein, we proposed a controllable and effective strategy to fractionate lignin by only changing the ratio of ethanol/water (V/V) as mixture solvent. This gradient extraction method effectively removed the part of lignin with small molecular and branching structure, thus selectively getting the fractionated lignin with high molecular weight, narrow polydispersity index, and good linear structure. Fortunately, when the ratio of ethanol/water was 6:4, the corresponding LCNFs (LCNFs-L60) was obtained with large specific surface area, independent filamentous morphology networks and excellent electrochemical property. Its specific capacitance was up to 405.8 F/g. This way features controllable and sustainable for preparing high-quality LCNFs supercapacitors., (Copyright © 2021 Elsevier B.V. All rights reserved.)