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61.
Wenjie Wang Xiaoxia Hu Lingyu Li Wei Jing Anran Guo Haiyan Du 《Ceramics International》2019,45(6):6723-6729
Here, we developed silica/mullite fiber composite membranes with double-layer structure by a simple vacuum procedure for the removal of sub-micrometer dust. The support with three-dimensional skeleton structure exhibited high porosity (higher than 90%), low density (lower than 0.25?g/cm3) and high compressive strength (higher than 0.55?MPa) at 1000?°C. By controlling the mass ratio of silica sol to mullite fiber, we can obtain uniform and complete filtering layers with different thicknesses. The composite membranes exhibited high PM filtration efficiency with 99% for 1–10?µm, 97% for 0.5?µm and 90% for 0.3?µm. These samples had high air flow with very low pressure drop (lower than 600?Pa when airflow velocity reached 1?m/s). These results indicated that the silica/mullite fiber composite membranes were very promising for PM pollution control in the field of hot gas filtration. 相似文献
62.
Amani Al-Othman Paul Nancarrow Muhammad Tawalbeh Ahmad Ka'ki Karim El-Ahwal Bassam El Taher Malek Alkasrawi 《International Journal of Hydrogen Energy》2021,46(8):6100-6109
Composite membranes composed of zirconium phosphate (ZrP) and imidazolium-based ionic liquids (IL), supported on polytetrafluoroethylene (PTFE) were prepared and evaluated for their application in proton exchange membrane fuel cells (PEM) operating at 200 °C. The experimental results reported here demonstrate that the synthesized membrane has a high proton conductivity of 0.07 S cm?1, i.e, 70% of that reported for Nafion. Furthermore, the composite membranes possess a very high proton conductivity of 0.06 S cm?1 when processed at 200 °C under completely anhydrous conditions. Scanning electron microscopy (SEM) images indicate the formation of very small particles, with diameters in the range of 100–300 nm, within the confined pores of PTFE. Thermogravimetric analysis (TGA) reveals a maximum of 20% weight loss up to 500 °C for the synthesized membrane. The increase in proton conductivity is attributed to the creation of multiple proton conducting paths within the membrane matrix. The IL component is acting as a proton bridge. Therefore, these membranes have potential for use in PEM fuel cells operating at temperatures around 200 °C. 相似文献
63.
《International Journal of Hydrogen Energy》2021,46(56):28435-28449
In this study, a corrosion-stable silica membrane was developed to be used in H2 purification during the hydrogen iodide decomposition (2HI → H2 + I2), which is a new application of the silica membranes. From a practical perspective, the membrane separation length was enlarged up to 400 mm and one end of the membrane tubes was closed to avoid any thermal variation along the membrane length and sealing issues. The silica membranes consisted of a three-layer structure comprising a porous α-Al2O3 ceramic support, an intermediate layer, and a top silica layer. The intermediate layer was composed of γ-Al2O3 or silica, and the top silica layer that is H2 selective was prepared via counter-diffusion chemical vapor deposition of a hexyltrimethoxysilane.To the best of our knowledge, this is the first report of 400-mm-long closed-end silica membranes supported on Si-formed α-Al2O3 tubes produced via chemical vapor deposition method. A 400-mm-long closed-end membrane using a Si-formed α-Al2O3 tube exhibited a higher H2/SF6 selectivity of 1240 but lower H2 permeance of 1.4 × 10−7 mol Pa−1 m−2 s−1 with compared with the membrane using a γ-Al2O3-formed α-Al2O3 tube (907 and 5.6 × 10−7 mol Pa−1 m−2 s−1, respectively). The membrane using the Si-formed α-Al2O3 tube was more stable in corrosive HI gas than a membrane with a γ-Al2O3-formed α-Al2O3 tube after 300 h of stability tests. In conclusion, the developed silica membranes using the Si-formed α-Al2O3 tubes seem suitable for membrane reactors that produce H2 on large scale using HI decomposition in the thermochemical iodine–sulfur process. 相似文献
64.
Muhammad Zia ul Mustafa Hilmi bin Mukhtar Nik Abdul Hadi Md Nordin Hafiz Abdul Mannan Rizwan Nasir Nabilah Fazil 《化学工程与技术》2019,42(12):2580-2593
Flue gas emissions and the harmful effects of these gases urge to separate and capture these unwanted gases. Ionic liquids due to negligible vapor pressure, thermal stability, and wide electrochemical stability have expanded its application in gas separations. A comprehensive overview of the recent developments and applications of ionic liquid membranes (ILMs) for gas separation is given. The three general classifications of ILMs, such as supported ionic liquid membranes (SILMs), ionic liquid polymeric membranes (ILPMs), and ionic liquid mixed‐matrix membranes (ILMMMs) along with their applications, for the separation of various mixed gases systems is discussed in detail. Furthermore, issues, challenges, computational study, and future perspectives for ILMs are also considered. 相似文献
65.
Wenmin Zhang Cheng Peng Defang Liu Yangfang Cheng Jianqing Wu 《Ceramics International》2019,45(9):11607-11614
In order to improve the gas permeability and thermal shock resistance of the ceramic membranes applied in high temperature gas-solid separation techniques, fused silica and graphite particles were used as the primary raw material and pore-former agent, and the spray coating based-on PVA sealing was applied to prepare the separation membrane. These approaches remarkably decreases filtration resistance by increasing support permeability and reducing the intrusion of ceramic membrane forming particles into the support as well as the thickness of the membrane. The fabricated membrane had an average pore diameter of 9.85?μm and a gas permeability value of 8.2?×?104?m3/(m2 h bar), its dust removal efficiency reached 98.6%. 相似文献
66.
Surrounding vegetation, animal, human and microbiological decomposition are the strong source of humic acid (HA) falling into the surface water bodies through rain runoff in the monsoon. HA contains various functional groups, such as carboxylic, phenolic, hydroxyl, and quinine, which are the major foulant. Contact of HA may have an adversarial health issue to human beings namely goiter, black foot, and cancer disease. The maximum permissible limit of HA in drinking water should be less than 2 ppm as per the Environmental Protection Agency (EPA). The membrane technology has prevailed a prominent place worldwide in chemical, water and wastewater treatment technologies. The proposed work is focused on the blending of organic-water soluble polymer polyethylene glycol 6000 as a pore-forming agent and inorganic salt lithium bromide (LiBr) as membrane morphology modifier with polyvinylidene fluoride host polymer in the N,N-Dimethylacetamide solvent. All fabricated membranes were characterized for functional groups and morphology. The total number of pores per unit surface area of membrane for membranes M-LiBr-0, M-LiBr-1, M-LiBr-2, and M-LiBr-3 are 2 × 1013, 2.3 × 1014, 2.7 × 1014 and 2.82 × 1014, respectively. The static water contact angle was decreased from 68.2° to 50.6° with an increase in the content of LiBr from 0 to 3 wt%. The order of pure water flux and hydraulic permeability of the membrane was M-LiBr-0 < M-LiBr-1 < M-LiBr-2 < M-LiBr-3. The HA rejection of the membrane was also increased from 90.13% to 96.24% with LiBr content due to a decrease in pore size of the membrane with the addition of LiBr content. 相似文献
67.
Reduced graphene oxide (rGO) membranes have been intensively evaluated for desalination and ionic sieving applications,benefiting from their stable and well-confined interlayer channels.However,rGO membranes generally suffer from low permeability due to the high transport resistance resulting from the narrowed two-dimensional (2D) channels.Although high permeability can be realized by reducing membrane thickness,membrane selectivity normally declines because of the formation of non-selective defects,in particular pinholes.In this study,we demonstrate that the non-selective defects in ultrathin rGO membranes can be effectively minimised by a facile posttreatment via surface-deposition of graphene quantum dots (GQDs).The resultant GQDs/rGO membranes obtained a good trade-off between water permeance (14 L·m-2·h-1·MPa-1) and NaCl rejection (91%).This work provides new insights into the design of high quality ultrathin 2D laminar membranes for desalination,molecular/ionic sieving and other separation applications. 相似文献
68.
Silicon oxycarbide (SiOC) fibers with different chemical compositions were successfully fabricated by electrospinning a mixture of polyvinylpyrrolidone (PVP) and commercially available polymethylsilsesquioxane (MK) or polymethylphenylsilsesquioxane (H44) preceramic polymers, followed by cross‐linking and pyrolysis at 1000°C in Argon. The influence of the processing procedure (solvent selection, cross‐linking catalyst and additives) on the morphology of the produced fibers was investigated. For the MK/isopropanol system, the introduction of 20 vol% N,N‐dimethylformamide (DMF) enabled to decrease the diameter of the as‐spun fibers from 2.72 ± 0.12 μm to 1.65 ± 0.09 μm. For the H44/DMF systems, beads‐free fibers were obtained by adding 50 vol% choloroform. After pyrolysis, the resultant SiOC fibers derived from MK and H44 resins possessed uniform morphology, with an average diameter of 0.97 ± 0.07 μm and 1.07 ± 0.08 μm, respectively. Due to their different chemical compositions, the MK‐derived and H44‐derived SiOC ceramic fibers could find different potential applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39836. 相似文献
69.
A method based on molecular imprinting technique was presented for preparing protein‐imprinted agarose gel membrane (AGM) under moderate conditions, and the influencing factors such as molecular weights and modified chemical groups on the adsorption ability and selectivity of AGMs were investigated. The agaroses used for AGMs were prepared through ultrasonic degradation, oxidation degradation, gel‐melting method, and sulfation, respectively. Bovine serum albumin (BSA) and hemoglobin were selectively recognized on AGMs. Results showed that the molecular weight was the most crucial influencing factor for the protein recognition ability of AGMs. The lower and upper limit of molecular weight was 100 and 130 kDa, respectively, where the AGMs could maintain both good mechanical strength and high recognition ability, with K value around 4.0. The enhancement of ionic strength could make the imprinting effect disappeared even when the concentration of salt was as low as 2 mmol/L. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40323. 相似文献
70.
Effect of gas permeation temperature and annealing procedure on the performance of binary and ternary mixed matrix membranes of polyethersulfone,SAPO‐34, and 2‐hydroxy 5‐methyl aniline 下载免费PDF全文
This study investigated the effect of annealing time and temperature on gas separation performance of mixed matrix membranes (MMMs) prepared from polyethersulfone (PES), SAPO‐34, and 2‐hydroxy 5‐methyl aniline (HMA). A postannealing period at 120°C for a week extensively increased the reproducibility and stability of MMMs, but for pure PES membranes no post‐annealing was necessary for stable and reproducible performance. The effect of operation temperature was also investigated. The permeabilities of H2, CO2, and CH4 increased with increasing permeation temperature from 35°C to 120°C, yet CO2/CH4 and H2/CH4 selectivities decreased. PES/SAPO‐34/HMA ternary and PES/SAPO‐34 binary MMMs exhibited the highest ideal selectivity and permeability values at all temperatures, respectively. For H2/CO2 pair, when temperature increased from 35°C to 120°C, selectivity increased from 3.2 to 4.6 and H2 permeability increased from 8 to 26.5 Barrer for ternary MMM, demonstrating the advantage of using this membrane at high temperatures. The activation energies were in the order of CH4 > H2 > CO2 for all membranes. PES/SAPO‐34/HMA membrane had activation energies higher than that of PES/SAPO‐34 membrane, suggesting that HMA acts as a compatibilizer between the two phases. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40679. 相似文献