The biggest challenge surrounding application of polymeric membranes for gas separation is their trade–off between gas permeation and selectivity. Therefore, the use of mixed matrix membranes (MMMs) comprising inorganic materials embedded into a polymer matrix can overcome this issue. In this work, PES flat sheet membrane and MMMs consists of 10 wt.% of rGO/ZIF-8 hybrid nanofillers were fabricated via dry/wet phase inversion process. Dip‐coating technique was then used to deposit PEBAX selective layer onto the surface of rGO/ZIF-8 PES support. The effects of PEBAX coating solution concentrations (2, 3 and 4 wt.%) on the permselectivity of CO2 and CH4 were investigated. The as-prepared rGO/ZIF-8 nanofillers and MMMs were characterized by fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (SEM) prior to gas separation performance study. Gas permeation testing was carried out at operating pressure of 1, 3 and 5 bar using CO2 and CH4 gasses. It was observed that the prepared PES membranes and rGO/ZIF-8 PES MMMs did not have any selectivity towards the gases although their permeability was high. As the concentration of PEBAX coating solution increased, thicker coating layer was formed. Therefore, the permeability of CO2 rapidly dropped but the CO2/CH4 selectivity increased significantly up to 38.4. Results indicated that the use of 2 wt.% of PEBAX was not effective to form homogenous coating layers on PES membrane and to cover any defects on membrane surfaces, thus, possessing low selectivity of CO2/CH4. The high gas separation performances obtained in this work was due to the synergistic effect rGO and ZIF-8 crystals. In the rGO/ZIF-8 MMMs, the dispersibility are enhanced due to the presence of distorted rGO sheets, while the ZIF-8 component ensure the porosity of the nanofillers and permit gas interactions with the metallic sites and functional groups on the organic linker. These sites facilitate the reactive adsorption leading to enhanced CO2 adsorption as compared to CH4.
Two types of alumina ceramic membrane in hollow fibre shape was used in this study. Both alumina hollow fibres (AHF) were sintered at different temperatures; (a) 1350oC and (b) 1450oC. In order to improve the catalytic activity of the alumina membrane for oxygen separation purposes, surface modification of the membranes was carried out using La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite catalyst. LSCF was synthesised using simple Pechini sol-gel method. The evaporation time and temperature of the LSCF-sol were varied to obtain various viscosity of catalytic sol. From XRD analysis, pure LSCF perovskite structure formed at temperature at 850oC. The morphological of unmodified and surface-modified alumina hollow fibre membranes (AHF) were studied using FESEM. The effect of LSCF catalytic sol viscosity was studied and it was found that as the viscosity of the sol increases, the amount of catalyst deposited on the alumina hollow fibre were increased. Besides, the amount of catalyst deposited on 1350 AHF was found to be higher than 1450 AHF. This result is supported by the result of pore distribution data whereby 1350 AHF was observed to be more porous than 1450 AHF, with porosity percentage of 40.38% and 28.80%, respectively. Although higher viscosity of catalytic sol could lead to a high amount of catalyst deposited on the AHF substrate, there is a tendency for micro-cracks to develop. Thus, the viscosity of the catalytic sol is important to control in order to have higher oxygen permeation flux.
Grafting polymerization by reactive small molecules involves the formation of graft copolymers from a reaction between polymers and monomers. Monomer units can be propagated onto the polymer backbone to form a graft structure. In the polymer processing industry, the internal mixer is the most important piece of machinery. The study used the internal mixer as a reactor to make a reactive process with the interest in residence time,as the residence time is importance in the chemical reaction. By increase the residence time, the optimum degree of grafting may be occurred. The objectives of this study are to increase the knowledge and understanding of the internal mixer process, determine optimum residence time process variables for grafting LLDPE and study the effect of the residence time toward the LLDPE grafting process. Several residence times was choosing for the specified sample, to study the effect of the residence time which were 60 s, 120 s, 180 s, 240 s, 300 s and 600 s. Degree of grafting (DOG) was calculated to determine the grafting of LLDPE grafted copolymers and a series of samples in which degrees of grafting had been determined by chemical titration. Residence time at 300 s produces the optimum DOG of monomer onto polymer. Longer residence time will produce high degree of grafting but will cause other issues such as increasing in gel content and lower the mechanical properties of the grafted polymer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.