The ever-increasing oil spill accidents from industries and the daily life have caused serious economic loss, destroyed the ecological environment and threatened human health. In order to solve this ...problem, designing and fabricating efficient separation membrane materials is an efficient way for oil/water emulsion separation and thus has aroused tremendous attention. We present a comprehensive overview on the separation membrane materials with controlled pore structure, tunable wettability for highly efficient oil/water emulsion separation. Separation mechanism was introduced at first, followed by introduction of the most frequently studied membrane materials. Based on the membrane substrate, general oil/water emulsion separation membrane can be categorized into polymer membrane, inorganic membrane, metal mesh membrane, gel membrane and biomass membrane. Besides, faced with the common problem of membrane pollution and damage, special functional membranes such as self-cleaning membrane, self-healing membrane, Janus membrane, and smart responsive membrane have aroused wide attention in recent years. For each membrane material, representative studies have been summarized, focusing on the synergy influence of the porous structure and selective wettability on the oil/water emulsion separation performance. Finally, the challenges, current trends and future perspectives of the oil/water emulsion separation membrane materials have also been proposed.
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•This article reviews the latest research work published in the past five years.•The perspective of raw materials, fabrication methods, and application performance have been summarized.•Development trend and challenge of each material are also concluded in the review.
Developing adsorptive separation processes based on C2H6‐selective sorbents to replace energy‐intensive cryogenic distillation is a promising alternative for C2H4 purification from C2H4/C2H6 ...mixtures, which however remains challenging. During our studies on two isostructural metal–organic frameworks (Ni‐MOF 1 and Ni‐MOF 2), we found that Ni‐MOF 2 exhibited significantly higher performance for C2H6/C2H4 separation than Ni‐MOF‐1, as clearly established by gas sorption isotherms and breakthrough experiments. Density‐Functional Theory (DFT) studies showed that the unblocked unique aromatic pore surfaces within Ni‐MOF 2 induce more and stronger C−H⋅⋅⋅π with C2H6 over C2H4 while the suitable pore spaces enforce its high C2H6 uptake capacity, featuring Ni‐MOF 2 as one of the best porous materials for this very important gas separation. It generates 12 L kg−1 of polymer‐grade C2H4 product from equimolar C2H6/C2H4 mixtures at ambient conditions.
Benefiting from the unblocked unique aromatic pore surfaces, suitable pore spaces and pore volumes, Ni‐MOF 2 displays high separation performance for C2H6/C2H4 separation and produces polymer‐grade C2H4 with high productivity (12 L kg−1) by a single separation process.
The fractal velocity pattern in symmetric kink-antikink collisions in ϕ4 theory is shown to emerge from a dynamical model with two effective moduli: the kink-antikink separation and the internal ...shape mode amplitude. The shape mode usefully approximates Lorentz contractions of the kink and antikink, and the previously problematic null vector in the shape mode amplitude at zero separation is regularized.
In The Supreme Court and Constitutional Democracy John Agresto traces the development of American judicial power, paying close attention to what he views as the very real threat of judicial ...supremacy. Agresto examines the role of the judiciary in a democratic society and discusses the proper place of congressional power in constitutional issues. Agresto argues that while the separation of congressional and judicial functions is a fundamental tenet of American government, the present system is not effective in maintaining an appropriate balance of power. He shows that continued judicial expansion, especially into the realm of public policy, might have severe consequences for America's national life and direction, and offers practical recommendations for safeguarding against an increasingly powerful Supreme Court. John Agresto's controversial argument, set in the context of a historical and theoretical inquiry, will be of great interest to scholars and students in political science and law, especially American constitutional law and political theory.
02 In The Supreme Court and Constitutional Democracy John Agresto traces the development of American judicial power, paying close attention to what he views as the very real threat of judicial supremacy. Agresto examines the role of the judiciary in a...
In The Supreme Court and Constitutional Democracy John Agresto traces the development of American judicial power, paying close attention to what he views as the very real threat of judicial supremacy. Agresto examines the role of the judiciary in a democratic society and discusses the proper place of congressional power in constitutional issues. Agresto argues that while the separation of congressional and judicial functions is a fundamental tenet of American government, the present system is not effective in maintaining an appropriate balance of power. He shows that continued judicial expansion, especially into the realm of public policy, might have severe consequences for America's national life and direction, and offers practical recommendations for safeguarding against an increasingly powerful Supreme Court. John Agresto's controversial argument, set in the context of a historical and theoretical inquiry, will be of great interest to scholars and students in political science and law, especially American constitutional law and political theory.
02 In The Supreme Court and Constitutional Democracy John Agresto traces the development of American judicial power, paying close attention to what he views as the very real threat of judicial supremacy. Agresto examines the role of the judiciary in a...
In The Supreme Court and Constitutional Democracy John Agresto traces the development of American judicial power, paying close attention to what he views as the very real threat of judicial supremacy. Agresto examines the role of the judiciary in a democratic society and discusses the proper place of congressional power in constitutional issues. Agresto argues that while the separation of congressional and judicial functions is a fundamental tenet of American government, the present system is not effective in maintaining an appropriate balance of power. He shows that continued judicial expansion, especially into the realm of public policy, might have severe consequences for America's national life and direction, and offers practical recommendations for safeguarding against an increasingly powerful Supreme Court. John Agresto's controversial argument, set in the context of a historical and theoretical inquiry, will be of great interest to scholars and students in political science and law, especially American constitutional law and political theory.
02 In The Supreme Court and Constitutional Democracy John Agresto traces the development of American judicial power, paying close attention to what he views as the very real threat of judicial supremacy. Agresto examines the role of the judiciary in a...
Separation of inert nitrogen from natural gas by membranes is much more energy-saving than cryogenic distillation but very challenging because the size difference of both gas molecules is quite ...small. Herein, high-quality and N2-selective SSZ-13 membranes on α-alumina tubes were prepared using a novel synthesis approach called seeded-gel synthesis. Seeded-gel synthesis was more convenient and credible than the conventional secondary growth because a seeding step on the substrate was omitted for the former method. The effect of calcination atmosphere on the quality of membranes was also discussed. SSZ-13 membranes had the fewest defects when ozone calcination was used. The predicted values of single-component N2 and CH4 permeances by the Maxwell-Stefan equations agreed well with the experimental ones. The SSZ-13 membrane exhibited ultrahigh N2 permeance of 850 × 10−9 mol m−2 s−1 Pa−1 (equals 2500 GPU) and a high N2/CH4 selectivity of 13.5 at 298 K and 0.303 MPa feed pressure (absolute). Membrane preparation by seeded-gel method had good reproducibility. The effects of temperature, pressure drop and feed flow rate on membrane performances were investigated for N2/CH4 mixture separations. The membrane also displayed good separation performance in N2/CH4 system either at 2.6 MPa feed pressure or under humid conditions. The continuous SSZ-13 thin membranes prepared by the simple seeded-gel synthesis showed great potentials for energy-efficient N2 removal from unconventional gases.
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•Highly N2-permeable SSZ-13 membranes were synthesized by novel seeded-gel synthesis.•The best membrane showed N2 permeance of 2500 GPU and N2/CH4 selectivity of 13.5.•Ozone calcination at low temperature reduced the formation of the defects.•The membrane had good separation performance for high-pressure and humid mixtures.
•High pressure CO2/CH4 separation of the optimized MMMs with CO2-philic MOFs.•Simulating an actual natural gas separation condition (pressure, feed, temperature).•At highest pressure, the effect of ...H2S (50,000 ppm) in feed was investigated.•MMMs showed CO2- and H2S-induced plasticization suppression.•Revealed reversible competitive sorption, also increased total acid gas selectivity.
The gas separation properties of 6FDA-DAM mixed matrix membranes (MMMs) with three types of zirconium-based metal organic framework nanoparticles (MOF NPs, ca. 40 nm) have been investigated up to 20 bar. Both NPs preparation and MMMs development were presented in an earlier publication that reported outstanding CO2/CH4 separation performances (50:50 vol% CO2/CH4 feed at 2 bar pressure difference, 35 °C) and this subsequent study is to demonstrate its usefulness to the natural gas separation application. In the current work, CO2/CH4 separation has been investigated at high pressure (2–20 bar feed pressure) with different CO2 content in the feed (10–50 vol%) in the temperature range 35–55 °C. Moreover, the plasticization, competitive sorption effects, and separation of the acid gas hydrogen sulfide (H2S) have been investigated in a ternary feed mixture of CO2:H2S:CH4 (vol% ratio of 30:5:65) at 20 bar and 35 °C. The incorporation of the Zr-MOFs in 6FDA-DAM enhances both CO2 permeability and CO2/CH4 selectivity of this polymer. These MMMs exhibit high stability under separation conditions relevant to an actual natural gas sweetening process. The presence of H2S does not induce plasticization but increases the total acid gas permeability, acid gas/CH4 selectivity and only causes reversible competitive sorption. The overall study suggests a large potential for 6FDA-DAM Zr-MOF MMMs to be applied in natural gas sweetening, with good performance and stability under the relevant process conditions.
Significance We have developed a unique approach for the separation of particles and biological cells through standing surface acoustic waves oriented at an optimum angle to the fluid flow direction ...in a microfluidic device. This experimental setup, optimized by systematic analyses, has been used to demonstrate effective separation based on size, compressibility, and mechanical properties of particles and cells. The potential of this method for biological–biomedical applications was demonstrated through the example of isolating MCF-7 breast cancer cells from white blood cells. The method offers a possible route for label-free particle or cell separation for many applications in research, disease diagnosis, and drug-efficacy assessment.
Lack of clean water is a major global challenge. Membrane separation technology is an ideal choice for the treatment of industrial, domestic sewage owing to its low energy consumption and cost. ...However, membranes are highly susceptible to contamination, particularly during wastewater treatment, which has limited their practical applications in this field. Similarly, the flux of the membrane decreases with prolonged use due to its reduced interlayer spacing. Preparation of membranes with anticontamination properties and stable flux is the key to addressing this problem. In this study, a 2D heterostructure membrane with visible‐light‐driven self‐cleaning performance is prepared via a self‐assembly process. Notably, the addition of palygorskite increases the interlayer spacing of the graphene and heterojunction structures, which increases the flux of the membrane and avoids a decrease of the interlayer spacing of the membrane under pressure. The presence of a heterojunction with visible light catalytic properties effectively avoids membrane fouling and avoids a sharp decrease of the permeation flux. Importantly, the prepared 2D membrane has excellent separation performance for oil–water emulsions with both high flux and efficiency. These features suggest great potential for the prepared 2D membrane in wastewater treatment applications.
A visible‐light‐driven self‐cleaning 2D heterojunction membrane for stable oil‐in‐water emulsion separation with stable flux is introduced. The 2D heterostructure membranes are successfully fabricated via a self‐assembly method. The prepared membranes have a high permeation flux for stable oil‐in‐water emulsion separation and they exhibit a high‐flux, stable flow rate after multiple cycles, and excellent self‐cleaning properties for stable oil‐in‐water emulsions.
This Minireview focuses on the developments of the adsorptive separation of methane/nitrogen, ethene/ethane, propene/propane mixtures as well as on the separation of C8 aromatics (i.e. xylene ...isomers) with a wide variety of materials, including carbonaceous materials, zeolites, metal–organic frameworks, and porous organic frameworks. Some recent important developments for these adsorptive separations are also highlighted. The advantages and disadvantages of each material category are discussed and guidelines for the design of improved materials are proposed. Furthermore, challenges and future developments of each material type and separation processes are discussed.
This Minireview focuses on the developments of adsorbents for the separation and purification of hydrocarbons from, for example, methane/nitrogen, ethene/ethane, and propene/propane mixtures as well as for the separation of C8 aromatics (i.e. xylene isomers).
•PIM-1 showed excellent compatibility with MOF-801 filler.•The CO2-philic MOF-801 filler provided fast and selective transport channels for CO2.•MOF-801/PIM-1 mixed-matrix membranes revealed much ...higher CO2 permeability and CO2/N2 selectivity.•MOF-801/PIM-1 mixed-matrix membranes have good long-term working stability and good antiaging properties.
This work mainly studies the CO2 separation performance of a new type mixed-matrix membranes (MMMs) based on MOF-801 as the microporous filler and PIM-1 as the polymer matrix. MMMs was successfully formed via simple casting/solvent evaporation approach at room temperature. The samples were systematically characterized by SEM, XRD, TGA and FTIR, the permeability-selectivity of MMMs to CO2, O2 and N2 was studied by gas permeability test. The experimental results show that the uniform dispersion of the CO2-philic MOF-801 filler provides a channel for the rapid and selective transport of CO2, so the MOF-801/PIM-1 MMMs revealed much higher CO2 permeability and CO2/N2 ideal selectivity (CO2 = 9686 Barrer, CO2/N2 = 27, all selectivity in the paper is ideal) than pure polymer membrane. After 90-days aging test, the CO2 permeability of MMMs remains above 70%, which reflects its good anti-aging performance. After 120 h continuous gas permeability test, it also shows good long-term working stability. The experimental results show that the good gas separation performance of MMMsexceeds the Robeson upper bound (2008), showing good application prospect for practical greenhouse gas CO2 separation.
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