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The main objective of this study is to determine the best intermediate layer for tubular carbon membranes for H 2 and He separation. Intermediate layer was applied to strengthen interfacial adhesion between selective carbon layers and tubular support. Three different intermediate layers (alumina powder, carbon molecular sieve (CMS), and carbon pencil) had been evaluated to compare their influence towards the performance of gas separation of the carbon membrane. Tubular carbon membrane was fabricated from PI/NCC-based polymer blends which had been carbonized under Argon atmosphere at 800 °C with a heating rate of 3 °C/min. Based on the scanning electron microscopic (SEM) observations, carbon membrane with alumina powder as an intermediate layer had formed a smoother surface compared to other types of intermediate layers. A high performance of tubular carbon membrane was obtained by employing alumina powder as an intermediate layer, which exhibited the best selectivity of H 2 /N 2 and He/N 2 of 447.31 ± 1.45 and 471.72 ± 2.19, respectively. • Three different intermediate layers were used to obtain high separation performance. • High performance of tubular carbon membrane was obtained by employing alumina powder as an intermediate. • Carbonization under Argon atmosphere at 800 °C with a heating rate of 3 °C/min were conducted. • Highest selectivity of H 2 /N 2 and He/N 2 of 447.31 ± 1.45 and 471.72 ± 2.19 was achieved. [ABSTRACT FROM AUTHOR]

These past few decades, the separation of various gas mixtures problems in order to obtain high purity gases can be overcome by the introduction of membrane-based technology. This current research was focusing on the development of tubular carbon membranes (TCMs) from polymeric precursors for the separation of hydrogen and nitrogen. The fabrication of TCMs involved the dip coating technique and was using P84 co-polyimide as the main precursor by blending of nanocrystaline cellulose (NCC) as an additive. It was believed a slight adjustment on time, temperature, or environment of the carbonization protocol for the commercially available PI/NCC membranes can alter the final properties of the carbons produced. The modifications on the carbonization parameters such as stabilization conditions and heating rates during fabrication of PI/NCC-based carbon membranes could also affect their gas separation performance. A large variety of TCMs for gas separation have been developed by simple carbonization of a PI/NCC deposited on a ceramic tubular support. Herein, in this study, the effect of different heating rates (1, 3, 5, and 7 °C/min) and stabilization environment (Argon, Nitrogen, and Helium) were investigated for all resultant TCMs. As a result, it was observed that stabilization under Argon environment with heating rate of 3 °C/min produced carbon membranes with the best H 2 /N 2 separation and the highest selectivity of 434.68 ± 1.39, respectively. • The effect of stabilization environment and heating rates was investigated. • The results showed that stabilization under Argon environment produced carbon membranes with better performance. • 3 °C/min heating rates improved the membrane selectivity and permeability. • The prepared tubular carbon membrane demonstrated high hydrogen separation performance. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) was utilized to design the experiments at the settings of solution concentration, voltage and the collector distance. It also imparted the evaluation of the significance of each parameter on the resultant physico chemicals (proton conductivity, methanol permeability and water uptake). The investigations were carried out in the two-variable process domains of several collector distances as applied voltage and the solution concentration were varied at a fixed polymer molecular weight. The result showed that all three factors were found statistically significant in the production of void free electrospun SPEEK/Cloisite membrane. All responses were correlated to these variables by using a second order polynomial function. The optimum condition for void free electrospun SPEEK/cloisite was at 0.17 wt% concentration with applied voltage of 22.15 kV and 18.83 cm distance from needle tip to screen collector. [ABSTRACT FROM AUTHOR]

In this work, hybrid nanocomposites rice husk derived graphene (GRHA) and zeolitic imidazolate framework-8 (ZIF-8) were prepared for hydrogen adsorption. The main contribution of this study is the simplification of the synthesized GRHA/ZIF-8 hybrid nanocomposites. Besides that, the use of synthesized graphene from rice husk (RH) could help in overcoming environmental issue since disposal of RH is rather challenging. GRHA was obtained through calcining rice husk ash (RHA) at 900 °C for 2 h in a muffle furnace at atmospheric condition while the nanocomposite of GRHA/ZIF-8 was produced in free solvent condition using deionized water at room temperature for only 1 h. The N 2 adsorption-desorption indicated a type I isotherm. Interestingly, it was found that the BET specific surface area (BET SSA) of GRHA/ZIF-8 showed enhancement up to 3 times higher as compared to pristine GRHA with the addition of 0.2 g of GRHA. From the experimental data, the adsorption of H 2 by nanocomposite GRHA/ZIF-8 obeyed the pseudo-second order kinetic model and intraparticle diffusion model with R2 value up to 0.9890 and 0.8087 respectively at 12 bar. Moreover, the GRHA/ZIF-8 possessed highest hydrogen adsorption of 31.84 mmol/g at 12 bar. These impressive results are justified by the combination of ZIF-8's microporosity and GRHA's mesoporosity. • Rice husk derived graphene (GRHA) incorporated zeolitic imidazolate framework-8 (ZIF-8shows an enhanced hydrogen adsorption. • GRHA incorporated ZIF-8 (GRHA/ZIF-8) has a higher specific surface area as compared to pristine GRHA and ZIF-8. • KOH able to form porosity and increase the surface area of rice husk during the activation process. • Hydrogen adsorption capacity increases with time and specific surface area of the adsorbent. • The hydrogen adsorption at room temperature obey pseudo-second order model and intraparticle diffusion model. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane (PEM) fuel cells are considered a promising technology for generating power with water as a byproduct. Recently, sulfonated poly(arylene ether sulfone) (SPAES) has emerged as a most suitable alternative for PEM applications because of its high proton conductivity, high CO tolerance, and low fuel crossover. However, the existing SPAES polymeric membrane materials have poor chemical reactivity, mechanical processability, and thermal usability. Thus, the effects of mixing inorganic nanomaterials with SPAES polymers on proton conductivity, power density, fuel crossover, thermal and chemical stability, and durability are discussed in this review. Further, the progress in preparation methods and fuel cell characteristics by the addition of silica, clay, heteropolyacids (HPA), and carbon nanotubes (CNTs) in polymer membrane materials for PEM applications is also discussed. [ABSTRACT FROM AUTHOR]