Unsteady-state Computational Fluid Dynamics Modeling of Hydrogen Separation from H2/N2 Mixture

3D modeling of Pd/α-Al2O3 hollow fiber membrane by using computational fluid dynamic for hydrogen separation from H2/N2 mixture was considered in steady and unsteady states by using the concept of characteristic time. Characteristic time concept could help us to design and calculate surface to volume ratio and membrane thickness, and adjust the feed conditions. The contribution of resistance between the membrane and the gas phase could be analyzed by considering characteristic times. The effect of temperature on quasi-steady time  was examined at constant feed flow rate and pressure. As a result, when thickness of membrane was less than the critical amount, the surface resistance was important. According to the results, about 50% mass separation was obtained in the initial 8% period of permeation time. By enhancing temperature, membrane permeation and, consequently, hydrogen separation increased. The CFD results showed good agreement with experimental data

3D simulation of the cold extrusion process of non-symmetric section of tellurium-lead

In this paper, making use of the ABAQUS software, an extrusion simulation is made with Tellurium-lead alloy. In this respect, two kinds of die land and their effects on extrusion force are investigated. The results are compared with available experimental ones in some references. The results show that a straight-line product is achieved by adding die lands to the die (with two statements), which increases the extrusion load and the deformation of the metal significantly. Also is investigated that the amount of force increase in the second state decreased in comparison with the first state

β-Cyclodextrin modified PES hollow fiber membrane, a new strategy for bilirubin separation

The aim of this study was to synthesis and evaluates the capability of modified polyethersulfone (PES) hollow fiber membrane for bilirubin separation from patients’ blood. Cyclodextrin (CD) was grafted on the membrane surface via ester bond between hydroxyl groups in CD and sulfonate functional groups on the membrane surface. Surface modification not only improved the membrane hydrophilicity, but also inhibited bovine serum albumin (BSA) and platelets adhesion on the surface. Moreover, the modified membrane could adsorb bilirubin up to 51 mg/g membrane. In conclusion, the proposed system could be a promising candidate to be used instead of resins in hemoperfusion column

Effect of Different Additives on Separation Performance of Flat Sheet PVDF Membrane Contactor

This paper investigates effects of different additives on morphology and subsequently, separation performance of asymmetric flat sheet Polyvinylidene fluoride (PVDF) membranes to separate CO2 using membrane contractor. Five different additives from different chemical families including Lithium chloride (salt), Polyethylene glycol 400 (polymer), glycerol (weak anti-solvents), methanol (alcohols) and acetic acid (weak secondary solvents) were used for controlling the morphology of the fabricated membranes. The fabricated PVDF membranes were applied to separate CO2 from a gas mixture of (20/80 wt/wt) CO2/N2 by contacting with (20/80 wt/wt) Monoethanolamine/H2O as absorbent. The investigations revealed that among the all considered additives, glycerol has the most promising effect on the performance of CO2 separation from the feed gas mixture. Effects of operational parameters such as flow rate and temperature of absorbents on the separation performance were also studied. Investigations showed that the lowest level of temperature (30 ºC) and the highest level of the flow rate of absorbent (500 ) provide better separation performance. Additionally, the presence of glycerol increased absorption performance (η) from 0.63 to 0.78 (at the lowest level of flow rate) and from 0.79 to 0.91 (at the highest level of flow rate) compared to the bare PVDF membranes

Scalable synthesis of robust and stretchable composite wound dressings by dispersing silver nanowires in continuous bacterial cellulose

"Available online 31 July 2020"While silver nanoparticles are widely used to endow materials with antibacterial activity, silver nanowires (AgNWs) have not attracted much attention. Herein, the composites of bacterial cellulose (BC) and AgNWs were prepared through a novel step-by-step in situ biosynthesis which retains the three-dimensional network of BC. The results of water vapor permeability, water uptake rate, and water retention rate showed that the BC/AgNW wound dressings could absorb wound skin exudates and maintain moisture environments. Furthermore, the BC/AgNW dressings were robust and stretchable. More importantly, the BC/AgNW dressings exhibited sustained release of Ag+. The results from animal tests indicated that the BC/AgNW dressing with 38.4 wt% AgNWs exhibited higher expression levels of cytokeratin-10 and integrin-β4, greater proliferation of keratinocytes and formation of epithelial tissues and greatly improved skin regeneration over the bare BC. We propose that the integrated nanofibrous structure and the excellent and sustained antibacterial activity of AgNWs are responsible for the excellent in vivo wound healing ability and biocompatibility. These results suggest that the BC/AgNW composites have promising application as wound dressings.Y. Wan, S. Yang, and J. Wang contributed equally to this work, which was funded by the National Natural Science Foundation of China (Grant nos. 31870963, 51973058) and the Provincial Key Research and Development Program of Jiangxi (No. 20192ACB80008).info:eu-repo/semantics/publishedVersio

Anti-thrombogenicity and permeability of polyethersulfone hollow fiber membrane with sulfonated alginate toward blood purification

The main aim of this study was to evaluate the suitability of sulfonated alginate as a modifying agent to enhance the hemocompatibility of self-fabricated polyethersulfone (PES) hollow fiber membrane for blood detoxification. Sodium alginate was sulfonated with a degree of 0.6 and immobilized on the membrane via surface amination and using glutaraldehyde as cross-linking agent. Coating layer not only improved the membrane surface hydrophilicity, but also induced −39.2 mV negative charges on the surface. Water permeability of the modified membrane was enhanced from 67 to 95 L/m2·h·bar and flux recovery ratio increased more than 2-fold. Furthermore, the modified membrane presented higher platelet adhesion resistance (reduced by more than 90%) and prolonged coagulation time (35 s for APTT and 14 s for PT) in comparison with the pristine PES hollow fiber membrane, which verified the improved anti-thrombogenicity of the modified membrane. On the other hand, obtained membrane after 3 h coating could remove up-to 60% of the uremic toxins. According to the obtained data, sulfonated alginate can be a promising modifying agent for the future blood-contacting membrane and specially blood purification issues

Treatment of hyperbilirubinemia: various technologies and challenges

Bilirubin removal from blood and curing patients suffering from hyperbilirubinemia by surgery, medication or interventional therapies was common, previously. Alternative bilirubin separation techniques such as plasma exchange, affinity chromatography and etc., are efficient in reducing high levels of bilirubin with fewer side effects. However, due to the various causes and complications associated with hyperbilirubinemia, different strategies are needed for the treatment. This article offers a historical overview on these strategies, challenges and also outlines the technological advantages and disadvantages associated with various bilirubin removal techniques

Synthesis and characterization of poly(vinylidene fluoride) membrane containing hydrophobic silica nanoparticles for CO2 absorption from CO2/N2 using membrane contactor

The separation of carbon dioxide from CO2/N2 gas mixture using membrane-absorption technology has been investigated. Poly(vinylidene fluoride) (PVDF) membrane was prepared using phase inversion method with N, N-Dimethylacetamide (DMAc) as the solvent and monoethanolamine (20 wt%) was used as the carbon dioxide absorbent. The hydrophobic silica nanoparticles modified with vinyl groups used to raise the hydrophobic character of the prepared polymeric membranes. The chemical structure and hydrophobicity of the silica nanoparticles was studied. The mixed matrix membranes morphology, hydrophobicity, thermal and mechanical properties were investigated. The results showed that the nanoparticles were properly modified with vinyl groups and their contact angles increased from 34 to 131°. Low amount addition of nanoparticles to the polymeric solution caused macrovoid formation, while increasing the nanoparticles loading suppressed macrovoid formation. Carbon dioxide absorption efficiency has been increased by increasing loading of nanoparticles into the membrane because of its smaller pore size and higher hydrophobicity