Size-Sieving Separation of Hard-Sphere Gases at Low Concentrations through Cylindrically Porous Membranes

Soft Matter ◽  
2021 ◽  
Author(s):  
Yue Yu ◽  
Kai Zhang
Keyword(s):  
Hard Sphere ◽  
Porous Membranes ◽  
Separation Performance ◽  
General Strategy ◽  
Intrinsic Permeability ◽  
Separation Processes ◽  
Low Concentrations

Membranes are compelling devices for many industrial separation processes, which are all subject to the intrinsic permeability-selectivity tradeoff. A general strategy to enhance separation performance is to reduce the pore...

scholarly journals Durability and Recoverability of Soft Lithographically Patterned Hydrogel Molds for the Formation of Phase Separation Membranes

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 108
Author(s):  
Asad Asad ◽  
Masoud Rastgar ◽  
Hadi Nazaripoor ◽  
Mohtada Sadrzadeh ◽  
Dan Sameoto
Keyword(s):  
Phase Separation ◽  
Solvent Extraction ◽  
Cold Treatment ◽  
Porous Membranes ◽  
Separation Processes ◽  
Separation Membranes ◽  
Membrane Fabrication ◽  
Phase Separation Process ◽  
Continuous Use ◽  
Recovery Result

Hydrogel-facilitated phase separation (HFPS) has recently been applied to make microstructured porous membranes by modified phase separation processes. In HFPS, a soft lithographically patterned hydrogel mold is used as a water content source that initiates the phase separation process in membrane fabrication. However, after each membrane casting, the hydrogel content changes due to the diffusion of organic solvent into the hydrogel from the original membrane solution. The absorption of solvent into the hydrogel mold limits the continuous use of the mold in repeated membrane casts. In this study, we investigated a simple treatment process for hydrogel mold recovery, consisting of warm and cold treatment steps to provide solvent extraction without changing the hydrogel mold integrity. The best recovery result was 96%, which was obtained by placing the hydrogel in a warm water bath (50 °C) for 10 min followed by immersing in a cold bath (23 °C) for 4 min and finally 4 min drying in air. This recovery was attributed to nearly complete solvent extraction without any deformation of the hydrogel structure. The reusability of hydrogel can assist in the development of a continuous membrane fabrication process using HFPS.

Theoretical and Experimental Study of Hydrocyclone Performance and Equivalent Settling Area

2014 ◽  
Author(s):  
Reza Sabbagh ◽  
Michael G. Lipsett ◽  
Charles R. Koch ◽  
David S. Nobes
Keyword(s):  
Mathematical Model ◽  
Settling Tank ◽  
Performance Model ◽  
Separation Performance ◽  
Separation Processes ◽  
Gravity Settling ◽  
Approaches To Study ◽  
Equivalent Area ◽  
Solid Liquid ◽  
Solid Liquid Separation

Predicting the performance of a solid-liquid separation process can help in comparing different separators for selection and design. This can be applied to hydrocyclone technology which is used widely in industry due to being an inexpensive device that is easy to operate and maintain and which has no moving parts. Environmental concerns and technological issues in separation processes are motivating the design of higher efficiency systems with less capital and operating costs. There is a need therefore for, methods to compare different separation technologies. In spite of extensive research into hydrocyclone performance, a mathematical model that can predict the performance of a hydrocyclone for comparison with other centrifugal separators is rare in the literature. The main objective of this research is to apply theoretical and experimental approaches to study hydrocyclone performance in order to propose an applicable separation performance model that represents the whole hydrocyclone operating range. A mathematical model is developed to explore the performance of the separator and to predict the hydrocyclone’s equivalent area as compared to a continuous gravity settling tank. A performance chart that can be used for selection and design of hydrocyclones is the result of the model.

Transport of Gases in Porous Membranes

MRS Bulletin ◽  
1999 ◽  
Vol 24 (3) ◽  
pp. 41-45 ◽  
Author(s):  
Stratis V. Sotirchos ◽  
Vasilis N. Burganos
Keyword(s):  
Pore Space ◽  
Chemical Species ◽  
Molecular Size ◽  
Porous Membrane ◽  
Transport Processes ◽  
Porous Membranes ◽  
Gaseous Species ◽  
Interior Space ◽  
Separation Processes ◽  
Membrane Pore

The capability of membranes to affect differently, both qualitatively and quantitatively, the transport rates of chemical species of dissimilar chemical structure through their interior space renders them attractive for use in many separation problems. Extensive research efforts have thus been undertaken on the preparation and characterization of membrane materials and the study of the transport processes involved in their use in separation applications. The study of the transport of gaseous species through the pore space of porous membranes and the analysis and understanding of the mechanisms that are involved in this process are a very important, if not the most important, element in the development of membranebased separation processes.The resistance that a gaseous species encounters as it is transported through the pore space of a porous membrane is a function of its molecular properties, of its interaction with the material that makes up the walls of the pores, and of the membrane pore structure. Gaseous transport in pores can take place through various mechanisms, whose contribution to the overall transport rate of a particular species is, in general, determined by the strength of the interactions of the molecules of that species with the pore walls and by the relative magnitudes of three length scales that characterize the molecular size, the distance between pore walls, and the density of the fluid in the pore space.

Membrane Separation of CO2 from Natural Gas: A State-of-the-Art Review on Material Development

2013 ◽  
Vol 333 ◽  
pp. 135-147 ◽  
Author(s):  
Ahmad Abdul Latif ◽  
Jimoh K. Adewole ◽  
Suzylawati Binti Ismail ◽  
Leo Choe Peng ◽  
Abdullah S. Sultan
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Membrane Separation ◽  
Primary Source ◽  
Reference Source ◽  
Separation Performance ◽  
Separation Processes ◽  
Membrane Materials ◽  
Material Development ◽  
Separation Of Gas Mixtures

Natural gas (NG) processing and membrane technology are two very important fields that are of great significance due to increasing demand for energy as well as separation of gas mixtures. While NG is projected to be the number one primary source of energy by 2050, membrane separation is a commercially successful competitor to other separation techniques for energy efficient gas separation processes [1]. Most of the NG produced in the world is coproduced with acid gases such as CO2which need to be removed to increase the caloric value of NG. A comprehensive review of research efforts in CO2separation from natural gas is required to capture details of the current scientific and technological progresses on the development of new membrane materials with better separation performance, and the improvement of properties of the existing ones. This paper presents the progress that has been achieved in eliminating the limitations that dominate the large scale application of membrane materials at the present time. Various polymers that have been developed to resist plasticization and the method employed to fabricate these polymers are highlighted. Also the range of plasticization pressures (together with corresponding selectivities and permeabilities at these pressures) that have so far been achieved by these fabrication methods is presented. It is believed that this review will serve as a good reference source especially for research in design and development of membrane materials with better resistance to CO2-induced plasticization.

scholarly journals Effect of Stabilization Conditions on the Fabrication of Carbon Membranes for CO2 Separation

2017 ◽  
Vol 16 (1) ◽  
Author(s):  
W. N. W. Salleh ◽  
A. F. Ismail ◽  
M. A. Rahman
Keyword(s):  
Morphological Structure ◽  
Gas Permeation ◽  
Separation Performance ◽  
Separation Processes ◽  
Carbon Membranes ◽  
Air Atmosphere ◽  
N2 Atmosphere ◽  
Stabilization Condition ◽  
Molecular Sieving ◽  
Permeation Properties

Preparation of carbon membranes has rapidly attracted much attention in gas separation processes because of thermal and chemical stabilities and exhibit superior separation performance. Carbon hollow fiber membranes (CHFM)s derived from polymer blend of polyetherimide (PEI) and polyvinylpyrrolidone (PVP) were extensively prepared through stabilization under air atmosphere followed by carbonization under N2 atmosphere. The effects of the stabilization temperature on the morphological structure and gas permeation properties were investigated by means of scanning electron microscopy (SEM) and single gas permeation system. Experimental results indicate that the transport mechanism of small gas molecules of N2, CO2, and CH4 is dominated by the molecular sieving effect. Based on morphological structure and gas permeation properties, an optimum stabilization condition for the preparation of CHFM derived from PEI/PVP was found at 300°C under air atmosphere. The selectivity of about 55 and 41 for CO2/CH4 and CO2/N2, respectively, were obtained.

scholarly journals Permeate Flux in Ultrafiltration Membrane: A Review

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
A. Beicha ◽  
R. Zaamouch ◽  
N. M. Sulaiman
Keyword(s):  
Membrane Filtration ◽  
Membrane Separation ◽  
Size Range ◽  
Membrane Surface ◽  
Separation Performance ◽  
Permeate Flux ◽  
Predictive Capability ◽  
Separation Processes ◽  
Ultrafiltration Pressure ◽  
Rate Limiting

Membrane processes exist for most of the fluid separations encountered in industry. The most widely used is membrane ultrafiltration, pressure driven process which is capable of separating particles in the approximate size range of 0.001 to 0.1 μm. The design of membrane separation processes, like all other processes, requires quantitative expressions relating material properties to separation performance. The factors controlling the performance of ultrafiltration are extensively reviewed. There have been a number of seminal approaches in this field. Most have been based on the rate limiting effects of the concentration polarization of the separated particles at the membrane surface. Various rigorous, empirical and intuitive models exist, which have been critically assessed in terms of their predictive capability and applicability. The decision as to which of the membrane filtration models is the most correct in predicting permeation rates is a matter of difficulty and appears to depend on the nature of the dispersion to separated.

Computer simulation to predict size distribution of track-etched nanopores

2022 ◽  
Author(s):  
Shin-ichi Sawada
Keyword(s):  
Computer Simulation ◽  
Size Distribution ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
Separation Performance ◽  
Nanoporous Membranes ◽  
Separation Processes ◽  
Model Case ◽  
Computer Simulation Program ◽  
Grid Points

Abstract Track-etched nanoporous membranes prepared by swift heavy ion irradiation are promising for separation processes such as water purification. However, one drawback is that multiple pores are undesirably formed by pore overlapping to reduce separation performance. The techniques for predicting the size and amount of multiple pores in detail are still underdeveloped, which hinders the precise membrane design. In this study, a computer simulation program was developed to predict the size distribution of the track-etched pores. The program generates a number of single pores on the virtual grid plane to simulate random ion bombardment, finds multiple pores containing several single pores, and determines the multiple pore size by counting the inside grid points. All the multiple pores are categorized into different size classes, and the areal percentage occupied by the pores belonging to each size class is estimated. The simulation algorithm and the results of a model case simulation were described.

A Singlet Oxygen Generator with Rapid Separation Process

2011 ◽  
Vol 148-149 ◽  
pp. 1223-1226
Author(s):  
Yu Qiang Dai ◽  
Zhen Dong Liu ◽  
Xiao Bo Xu ◽  
Wen Wu Chen ◽  
Li Zhi Zhu ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Residence Time ◽  
Separation Performance ◽  
Separation Processes ◽  
Rapid Separation ◽  
Flow Reactors ◽  
Oxygen Generation ◽  
Oxygen Generator ◽  
Through Flow ◽  
Singlet Oxygen Generator

Singlet oxygen generator is the heart of chemical oxygen iodine lasers and has been the focus of research for many years. In this paper, a novel singlet oxygen generator with rapid separation technology is briefly put forward. To ensure short residence time, the design of reaction and separation processes happening simultaneously in through-flow reactors is dumpy shaped. By means of computational fluid dynamics, the calculations indicate that the residence time of O2(1Δ) in the new structure is about 15ms and the new SOG has excellent anti-entrainment and defoaming separation performance. The analytical results show the new structure is a feasible and promising technology in singlet oxygen generation cases.

scholarly journals Poly[3-ethyl-1-vinyl-imidazolium] diethyl phosphate/Pebax® 1657 Composite Membranes and Their Gas Separation Performance

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 224
Author(s):  
Irene R. Mazzei ◽  
Daria Nikolaeva ◽  
Alessio Fuoco ◽  
Sandrine Loïs ◽  
Sébastien Fantini ◽  
...  
Keyword(s):  
Gas Separation ◽  
Gas Transport ◽  
Time Lag ◽  
Composite Membranes ◽  
Industrial Applications ◽  
Mechanical Resistance ◽  
Separation Performance ◽  
Separation Processes ◽  
Neat Polymer ◽  
Diethyl Phosphate

Poly(ionic liquid)s are an innovative class of materials with promising properties in gas separation processes that can be used to boost the neat polymer performances. Nevertheless, some of their properties such as stability and mechanical strength have to be improved to render them suitable as materials for industrial applications. This work explored, on the one hand, the possibility to improve gas transport and separation properties of the block copolymer Pebax® 1657 by blending it with poly[3-ethyl-1-vinyl-imidazolium] diethyl phosphate (PEVI-DEP). On the other hand, Pebax® 1657 served as a support for the PIL and provided mechanical resistance to the samples. Pebax® 1657/PEVI-DEP composite membranes containing 20, 40, and 60 wt.% of PEVI-DEP were cast from solutions of the right proportion of the two polymers in a water/ethanol mixture. The PEVI-DEP content affected both the morphology of the dense membranes and gas transport through the membranes. These changes were revealed by scanning electron microscopy (SEM), time-lag, and gravimetric sorption measurements. Pebax® 1657 and PEVI-DEP showed similar affinity towards CO2, and its uptake or solubility was not influenced by the amount of PIL in the membrane. Therefore, the addition of the PIL did not lead to improvements in the separation of CO2 from other gases. Importantly, PEVI-DEP (40 wt.%) incorporation affected and improved permeability and selectivity by more than 50% especially for the separation of light gases, e.g., H2/CH4 and H2/CO2, but higher PEVI-DEP concentrations lead to a decline in the transport properties.

Numerical investigation of UF membrane to reduce energy consumption using double porosity approach

2018 ◽  
Vol 77 (12) ◽  
pp. 2907-2916
Author(s):  
S. Ghotbi ◽  
B. Pirzadeh ◽  
Davod Mohebbi-Kalhori ◽  
A. Abdollahi
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Double Porosity ◽  
Transmembrane Pressure ◽  
Separation Performance ◽  
Water And Wastewater Treatment ◽  
Separation Processes ◽  
The Third ◽  
Cross Section Area ◽  
Inner Surface

Abstract Hollow fiber (HF) membranes with circular geometry, are used in many separation processes such as water and wastewater treatment. Since optimization of energy efficiency is important for wastewater treatment, the aim of this study was to investigate the effect of non-circular geometry of the inner surface of the HF on the separation performance. To this purpose, the HF bundle has been assumed as a double porous media having two porosities and permeabilities. Since these two parameters are defined by the geometry of the porous medium, any change in the geometry affects their values and the media performance. Therefore, in this study a mathematical modeling has been divided into five categories, including circular, oval, square, rectangular and triangular geometries, and their geometric properties have been calculated based on three different strategies. The results have been compared with the data obtained from literature and showed that the membrane inner surface to cross-section area ratio (a), axial permeability, and porosity in the inner region for the non-circular HF are larger than that of the circular HF and a increased 16%, 27%, 35% and 65% in ellipse, square, rectangle and triangle geometry, respectively, in comparison with the circle. Axial permeability increased 98%, 68%, 63%, and 26% for a triangle, rectangle, ellipse, and square respectively in the third strategy when compared to the circle. Due to 50% feed flow rate reduction, maximum transmembrane pressure (TMP) reduction was 85% related to the rectangular geometry in the first strategy and minimum was 55% corresponding to the triangle in the third strategy. As a increased up to 65%, TMP reduced by up to 200% and consequently energy consumption and operating costs of the system are decreased.

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