Two‐dimensional nanosheets have shown great potential for separation applications because of their exceptional molecular transport properties. Nanosheet materials such as graphene oxides, ...metal–organic frameworks, and covalent organic frameworks display unique, precise, and fast molecular transport through nanopores and/or nanochannels. However, the dimensional instability of nanosheets in harsh environments diminishes the membrane performance and hinders their long‐term operation in various applications such as gas separation, water desalination, and ion separation. Recent progress in nanosheet membranes has included modification by crosslinking and functionalization that has improved the stability of the membranes, their separation functionality, and the scalability of membrane formation while the membranes’ excellent molecular transport properties are retained. These improvements have enhanced the potential of nanosheet membranes in practical applications such as separation processes.
Modification of nanosheet membranes by crosslinking and functionalization has improved their stability, their separation functionality, and the scalability of membrane production while retaining the membranes’ excellent molecular transport properties. These improvements have enhanced the potential of nanosheet membranes in practical applications such as separation processes.
Cell separation is broadly useful for applications in clinical diagnostics, biological research, and potentially regenerative medicine. Recent attention has been paid to label-free size-based ...techniques that may avoid the costs or clogging issues associated with centrifugation and mechanical filtration. We present for the first time a massively parallel microfluidic device that passively separates pathogenic bacteria cells from diluted blood with macroscale performance. The device was designed to process large sample volumes in a high-throughput, continuous manner using 40 single microchannels placed in a radial array with one inlet and two rings of outlets. Each single channel consists of a short focusing, gradual expansion and collection region and uses unique differential transit times due to size-dependent inertial lift forces as a method of cell separation. The gradual channel expansion region is shown to manipulate cell equilibrium positions close to the microchannel walls, critical for higher efficiency collection. We demonstrate >80% removal of pathogenic bacteria from blood after two passes of the single channel system. The massively parallel device can process 240 mL/h with a throughput of 400 million cells/min. We expect that this parallelizable, robust, and label-free approach would be useful for filtration of blood as well as for other cell separation and concentration applications from large volume samples. Biotechnol. Bioeng. 2010;107: 302-311.
This review highlights the recent advances and the current state-of-the-art in Mg/Li separation and lithium extraction technologies from salt lake brine. It provides new insights to this field from ...the view of resource sustainability.
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•Extracting lithium from brine is critical for energy storage applications.•Highlight the recent advances in Mg/Li separation and lithium extraction.•The current state-of-the-art of technologies is reviewed.•Provide new insights from the view of resource sustainability.•The comprehensive utilization of salt lake resources is realized.
Over the past few decades, the demand for lithium resources has increased significantly with the rapid development and extensive application of lithium-ion batteries. Extracting lithium from salt lake brine is of significance because of its abundance in brines. Numerous endeavours have addressed the challenges of magnesium/lithium separation from salt lake brines having high Mg/Li ratios with the aim of efficiently and sustainably recovering lithium resources. This review focuses on the latest advances in magnesium/lithium separation and lithium recovery from salt lake brines, including extraction, adsorption, membrane, and electrochemical methods as well as reaction-coupled separation technology. The features and adaptabilities of various methods are analysed from the viewpoint of the chemical structures of related materials, reaction mechanisms, properties, and applications. Among the available techniques, adsorption methods have great potential to be widely used. However, membrane methods have attracted attention owing to their low energy consumption and high separation rates; the advantages and limitations of nanofiltration, electrodialysis, bipolar membranes, and membrane capacitive deionisation are therefore summarised in this review. As representative electrochemical methods, the lithium ion capturing system and the rocking-chair battery system are reviewed, and the roles of various electrode materials in lithium recovery are analysed. Recently, reaction-coupled separation technology has emerged as an advantageous method for magnesium/lithium separation and lithium extraction. The ability of this technology to realise highly efficient magnesium/lithium separation while simultaneously preparing high-value magnesium-based functional materials from magnesium resources is discussed. The development of such methods that can comprehensively utilise the magnesium and lithium resources in salt lake brine is essential for resource sustainability.
Separation of acetylene (C2H2) from carbon dioxide (CO2) or ethylene (C2H4) is industrially important but still challenging so far. Herein, we developed two novel robust metal organic frameworks ...AlFSIX‐Cu‐TPBDA (ZNU‐8) with znv topology and SIFSIX‐Cu‐TPBDA (ZNU‐9) with wly topology for efficient capture of C2H2 from CO2 and C2H4. Both ZNU‐8 and ZNU‐9 feature multiple anion functionalities and hierarchical porosity. Notably, ZNU‐9 with more anionic binding sites and three distinct cages displays both an extremely large C2H2 capacity (7.94 mmol/g) and a high C2H2/CO2 (10.3) or C2H2/C2H4 (11.6) selectivity. The calculated capacity of C2H2 per anion (4.94 mol/mol at 1 bar) is the highest among all the anion pillared metal organic frameworks. Theoretical calculation indicated that the strong cooperative hydrogen bonds exist between acetylene and the pillared SiF62− anions in the confined cavity, which is further confirmed by in situ IR spectra. The practical separation performance was explicitly demonstrated by dynamic breakthrough experiments with equimolar C2H2/CO2 mixtures and 1/99 C2H2/C2H4 mixtures under various conditions with excellent recyclability and benchmark productivity of pure C2H2 (5.13 mmol/g) or C2H4 (48.57 mmol/g).
An unprecedented robust metal organic framework ZNU‐9 with a new wly topology and featuring multiple anion functionalities and hierarchical porosity was reported for simultaneous efficient C2H2/CO2 and C2H2/C2H4 separation with both high capacity and high selectivity.
As one of the green, renewable, and clean energy resources, hydrogen is widely developed and utilized throughout the world. Highly efficient membrane separation for hydrogen production is required to ...give promising gas permeance with enough H2 selectivity. The membranes are desired to be produced in large-scale, fast and facile methods. Here we report for the first time a kind of freestanding MXene-ZIF-8 dual-layered membrane for hydrogen separation. Fast synthesis of such membranes is realized by combining electrophoretic deposition (EPD) and fast current-driven synthesis (FCDS), achieving the assemble of MXene layer and growth of ZIF-8 layer, respectively, overcoming the traditional time-consuming vacuum filtration methods and solvothermal synthesis. The MXene-ZIF-8 dual-layered membrane prepared within 20 min exhibits significantly improved gas separation performance, whose H2/CO2 selectivity increases from 44 for the pristine MXene membrane to 77 with H2 permeance of 5.97 × 10−8 mol m−2 s−1 Pa−1. This concept of structure design of membrane can also be extended to other dual-layered membranes, including various 2D nanosheet layers combined with different MOF layers.
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•Freestanding MXene-ZIF-8 dual-layered membrane was prepared by EPD/FCDS in 21 min.•It exhibits high separation performance for H2/CO2 with selectivity of 77.•A MXene-ZIF-8 dual-layered membrane with large area of 525 cm2 was prepared.
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.
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•Key limitations in biosurfactant producing fermentations described.•Integrated separation techniques to overcome production challenges discussed.•Clear analysis of scalability of ...integrated separation technologies.•Economic evaluation of effect of integration separation technologies provided.
Environmentally friendly, microbially produced surfactants known as biosurfactants have recently seen an explosion in commercial activity and interest due to a reduction in the cost of production, though these costs still limit biosurfactant use in bulk applications. These high production costs are primarily the result of the typically low productivities of large scale biosurfactant production processes and hence the large production volumes required, as well as process engineering challenges related to the nature of the biosurfactant produced. This review details the use of integrated separation technologies, primarily gravity, membrane and foam fractionation separations, in integrated biosurfactant producing fermentations, to tackle these difficulties. An analysis of the scalability of the available technologies and the expected impact on process economics is presented, demonstrating the potential utility of integrated separation processes for bringing biosurfactants into mainstream commercialisation.
The topology and chemical functionality of metal–organic frameworks (MOFs) make them promising candidates for membrane gas separation; however, few meet the criteria for industrial applications, that ...is, selectivity of >30 for CO2/CH4 and CO2/N2. This paper reports on a dense CAU‐10‐H MOF membrane that is exceptionally CO2‐selective (ideal selectivity of 42 for CO2/N2 and 95 for CO2/CH4). The proposed membrane also achieves the highest CO2 permeability (approximately 500 Barrer) among existing pure MOF membranes with CO2/CH4 selectivity exceeding 30. State‐of‐the‐art atomistic simulations provide valuable insights into the outstanding separation performance of CAU‐10‐H at the molecular level. Adsorbent–adsorbate Coulombic interactions are identified as a crucial factor in the design of CO2‐selective MOF membranes.
This work proposes a pure metal–organic framework (CAU‐10‐H) membrane with high selectivity (>30) for CO2/CH4. Relationships among structure, Coulombic effect, and transport property of CO2 in the channel of CAU‐10‐H are investigated, which can lead to the design of highly CO2 selective ultramicroporous materials for membrane separation.
Membrane-based technology represents an emerging strategy for energy-efficient gas/liquid separation. Among various factors, dimensionality and microstructure of membrane materials played a dominant ...role in determining their separation performance. Recently, unique structural properties of two-dimensional (2D) nanomaterials with atomic size thickness are rapidly emerging as desirable building blocks for the design of high performance membranes. Among them, layered double hydroxides (LDHs), a representative of anionic clays, have attracted extensive interest and exhibited promising prospects for membrane applications due to their uniform interlayer galleries, which may permit precise molecular sieving in case the gallery height was comparable with kinetic diameters of guest molecules. Moreover, highly tunable chemical compositions and gallery height as well as the rich surface functionality of LDH building blocks further endowed them with unprecedented opportunities for efficient gas/liquid separation. This paper summarizes recent breakthrough in LDH-based separation membranes with particular emphasis on the opportunities and challenges facing their commercial applications.
Recent decades witnessed significant progress made in the field of two-dimensional molecular sieve separation membranes. layered double hydroxides (LDHs), as a representative of anionic two-dimensional molecular sieves, have been considered as an ideal candidate for high performance separation membranes. This paper summarized recent progress made in construction of LDH-based separation membranes emphasizing on opportunities and challenges facing their commercial applications. Display omitted
•The first review of the recent advances in layered double hydroxides (LDHs) for membrane–based separation processes.•LDHs membranes exhibit molecular sieving property for gas separation.•LDHs nanoparticles have been successfully added into various polymers for gas and liquid membranes separation.
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