Separation Technology Research Articles

Tailored Permeation Through ≈1 nm Thick Carbon Nanomembranes by Subtle Changes in Their Molecular Design.

Due to their nanoscale thickness (≈1 nm) and exceptional selectivity for permeation of gases, nanomembranes made of 2D materials possess high potential for energy-efficient nanofiltration applications. In this respect, organic carbon nanomembranes (CNMs), synthesized via electron irradiation-induced crosslinking of aromatic self-assembled monolayers (SAMs), are particularly attractive, as their structure can be flexibly tuned by choice of molecular precursors. However, tailored permeation of CNMs, defined by their molecular design, has not been yet demonstrated. In this work, it is shown that the permeation of helium (He), deuterium (D2) and heavy water (D2O) for CNMs synthesized from biphenyl-based SAMs on silver (C6H5-C6H4-(CH2)n-COO/Ag, n = 2-6) can be tuned by orders of magnitude by changing the structure of the molecular precursors by just a single methylene unit. The selectivity in permeation of D2O/D2 with an unprecedented value of 200000 can be achieved in this way. The temperature-dependent study reveals a clear correlation between the molecular design and the permeation mechanisms facilitating therewith tailored synthesis of molecular 2D materials for separation technologies.

Research on Magnetic Field of Permanent Magnet Rolls Arranged Periodically in Circumferential—Axial Direction

The separation of non-magnetic non-ferrous metals such as copper and aluminum from scrapped automobiles is a critical area of research due to the increasing number of end-of-life vehicles. Traditional eddy current separation methods have limitations, particularly in handling large-sized broken copper and aluminum parts. This paper proposes a novel magnetic roller model featuring a circumferential–axial periodic arrangement of permanent magnets. This study explores the external magnetic field distribution of this new roller design by constructing an equivalent current model, solving magnetic scalar potential equations, and employing simulation tools. The findings indicate that the new magnet array enhances both the magnetic field strength and the range of the external magnetic field, leading to improved separation efficiency of large-sized metal fragments. The results provide a theoretical basis for advancing the separation technology of large-sized broken copper and aluminum parts in scrapped automobiles, offering potential improvements in the recycling of non-ferrous metals from end-of-life vehicles.

Flow-electrode capacitive separation of organic acid products and recovery of alkali cations after acidic CO2 electrolysis

Acidic CO2 electrolysis, enhanced by the introduction of alkali cations, presents a strategic approach for improving carbon efficiency compared to processes conducted in neutral and alkaline environments. However, a significant challenge arises from the dissolution of both organic acids and alkali cations in a strongly acidic feed stream, resulting in a considerable energy penalty for downstream separation. In this study, we investigate the feasibility of using flow-electrode capacitive deionization (FCDI) technology to separate organic acids and recover alkali cations from a strongly acidic feed stream (pH ~ 1). We show that organic acids, such as formic acid and acetic acid, are retained in molecular form in the separation chamber, achieving a rejection rate of over 90% under all conditions. Alkali cations, such as K+ and Cs+, migrate to the cathode chamber in ionic form, with their removal and recovery significantly influenced by their concentration and the pH of the feed stream, but responding differently to the types and concentrations of organic acids. The energy consumption for the removal and recovery of K+ is 4 to 8 times higher than for Cs+, and the charge efficiency is significantly influenced by the types of organic acid products and alkali cations. We conduct a series of electrochemical measurements and analyze the impedance spectroscopy, identifying that hindered mass transfer governed the electrode process. Our findings underscore the potential of FCDI as an advanced downstream separation technology for acidic electrocatalysis processes.

Optimization of synthesis of cationic starches for wastewater sludge and microalgae separation

The implementation of stricter water protection legislation requires the development of novel environmentally friendly water treatment materials. A new method for the preparation of water soluble cationic starch flocculants using potato starch, 3-chloro-2-hydroxypropyltrimethylammonium chloride and CaO additive was developed and surface response methodology was successfully utilized for the optimization of degree of substitution in the cationization of potato starch with and without CaO additive. Based on the results of destabilization studies of model kaolin, wastewater sludge, and microalgae dispersion systems, optimized conditions ware proposed for obtaining an efficient, soluble, and biodegradable cationic starch flocculant with optimal structure. The duration of starch etherification reaction was reduced to <12 h to obtain soluble cationic starch derivatives with a degree of substitution of quaternary ammonium groups of 0.25, which retained the granular structure during synthesis. An efficient flocculation technology using anionic polymer and high content of biodegradable cationic flocculant was proposed. The highly efficient flocculation of microalgae suspensions using developed cationic starch derivative with the degree of substitution of cationic groups of 0.25 has been also achieved. The developed environmentally friendly cationic starches with tailored flocculation properties proofed to have a great potential in various water cleaning and separation technologies with prospects in wastewater treatment, agriculture or energy sectors.

Diffusive nature of different gases in graphite: Implications for gas separation membrane technology

Graphite membranes have gained attention in membrane technology for gas separation due to their high stiffness, strength, and stability in corrosive and high-temperature environments. Graphite exists naturally in geologic media and can also be prepared by synthetic processes. In- situ hydrogen (H2) production in petroleum reservoirs or H2 storage in depleted gas reservoirs results in contamination with CH4 and CO2. To address the separation challenge at the surface, a sustainable downhole wellbore membrane must be available to separate H2, leaving behind CO2 and other gases to improve operational economics. Currently, there are no studies in the literature on the self-diffusivity of gases (CO2, H2, and CH4) in graphite as a function of pore size. To overcome time constraints in diffusivity experiments, this work utilized mathematical models and molecular simulations to delineate the self-diffusivity of gases in graphite of different pore sizes.To acknowledge subsurface operational conditions during in situ hydrogen production, we considered a temperature of 360 K and a wide pressure spectrum from 2 MPa to 20 MPa. In this study, we explored the diffusive nature of H2, CH4, and CO2 gases in different nanopore-sized graphite using analytical and molecular simulation approaches. We validated the results by presenting unrestricted case density calculations. First, effective diffusivity was calculated using the mean free pore path, followed by gas adsorption at high pressures (10–20 MPa) and a temperature of 350 K. The study utilized theoretical models and molecular dynamics (MD) simulations to determine the self-diffusivity of gases in graphite systems with various structures.

Monitoring of floating structures using segmentation and object classification of remotely-sensed images

Abstract With the rapid development of Marine aquaculture, remote sensing monitoring of high space separation Marine floating raft aquaculture has become a key technology to ensure aquaculture efficiency and environmental sustainability. A novel multi-scale layered cascade capsule network (MSHCN) model is proposed to improve the accuracy and efficiency of remote sensing image analysis for high space separation Marine floating raft culture. Firstly, based on the basic principle of the capsule network, the traditional convolutional neural network is improved, and a multi-scale feature extraction mechanism is introduced to adapt to the diversity and complexity of images in the culture area. Secondly, by building a hierarchical cascade structure, the model can further improve its ability to capture small and large scale features, so as to better understand the spatial distribution characteristics of the farming environment. In addition, in the experimental part, we verified with real remote sensing data sets, and the results showed that the MSHCN model outperformed the current mainstream methods on several key performance indicators, including classification accuracy, detection speed and model generalization ability. Finally, the potential value of this model in practical application and future optimization direction is discussed, which provides a new idea and tool for the development of remote sensing monitoring technology for high space separation floating raft culture.

Application of drug delivery microspheres in cancer therapy

Microspheres are a novel drug delivery system, which provides a new approach for cancer therapy. Anti-cancer agents loaded in microspheres can be released in a controlled and sustained pattern, thereby enhancing the therapeutic efficacy and reducing the side effects and toxicity. The preparation methods for drug delivery microspheres include solvent evaporation, phase separation, spray drying, and microfluidic technology, each of these have advantages and limitations. Based on the preparation materials, drug delivery microspheres can be categorized into natural polymer microspheres, synthetic polymer microspheres and bioceramic microspheres. Natural polymer micro-spheres have good biocompatibility and degradability; synthetic polymer microspheres exhibit superior mechanical properties; bioceramic microspheres have good biocompatibility and specific biological functions, which are widely used in bone tissue engineering. Drug delivery microspheres are used for cancer treatment in various modalities, including photothermal therapy, photodynamic therapy, radioembolization, and immunotherapy, as well as chemotherapy. This article reviews the recent progress of microspheres as nano drug delivery system in cancer treatment to provide a reference for further clinical and translation research.

Synergistic impact of Fe–Zr in novel hybrid aminoclay catalytic TFC membrane for ultrafast emerging pollutant remediation

Finding new class of materials to overcome limitation in conventional membranes is a challenging task. Use of naturally stable and sustainable alternative materials stock is an emerging task. In this direction, a novel iron-zirconium hybrid aminoclay (FZ-AC) has emerged as a promising catalyst effectively employed to alleviate fouling concerns within the framework of a biopolymer-based thin film composite (TFC), constructed on a cellulose acetate (CA) support. Notably, FZ-AC exhibits remarkable catalytic activity in the degradation of foulants through potential free radicals generated from Fe and Zr active centres in synergy with oxidising agent. The optimised catalytic membrane (FZ-TFC-1) exhibited an ultrafast degradation of congo red (CR), eriochrome black-T (EBT), crystal violet (CV), methylene blue (MB), red-brown dye (RBn), bisphenol-A (BPA), azithromycin (AZC), and Cr(VI) within 4 min. The cooperative action of redox centres of Fe and Zr metal ions synergistically accelerated the swift production of reactive species and facilitated the efficient degradation of pollutants within a notably short timeframe. Furthermore, >95% of above dyes rejection was achieved with >67 L m−2.h−1 of flux. The results of a long-term study demonstrated that FZ-TFC membranes exhibit exceptional stability, retaining their performance for a duration up to 150 h. This extended period of stability underscores the superiority of these membranes over alternative counterparts, suggesting their robustness and reliability for sustained operation in various applications. This strategic utilization of FZ-AC representing a promising avenue for enhancing the efficacy and longevity of nanofiltration membranes, thereby advancing the frontier of membrane-based separation technologies.

Influence of dealloying on wetting behavior and adhesion properties of Cu-Zr-Al-Ag glassy ribbons

Abstract This research aims to clarify the correlation between dealloying conditions, surface chemistry, and wettability behavior in Cu-based metallic glassy ribbons. Investigating the influence of dealloying on the wettability of Cubased glassy ribbons is the focus of this study. Glassy ribbons composed of the Cu-Zr-Al(-Ag) alloy family were dealloyed in hydrofluoric acid (HF) solution, with molarities ranging from 0.01 M to 0.5 M for durations between 2 and 10 minutes, followed by a thorough cleaning in distilled water. The impact of dealloying parameters on water droplet adhesion was evaluated together with the droplets’ ability to resist detachment after mechanical disturbances. Such insights are pivotal for the development of novel superhydrophobic or superhydrophilic materials, which could find applications in diverse fields such as microfluidics and oil-water separation technologies. The research demonstrates the substantial effects of dealloying on Cu-Zr-Al(-Ag) glassy ribbons, showing significant alterations in surface morphology, elemental composition, and wettability, all influenced by dealloying conditions

Proposal and performance evaluation of a new parallel plate continuous cell separation device using dielectrophoresis.

Along with the rapid development of cellular biological research in recent years, there has been an urgent need for a high-speed, high-precision method of separating target cells from a highly heterogeneous cell population. Among the various cell separation technologies proposed so far, dielectrophoresis (DEP)-based approaches have shown particular promise because they are noninvasive to cells. We have developed a new DEP-based device to separate large numbers of live and dead cells of the human mammary cell line MCF10A. In this study, we validated the separation performance of this device. The results showed the successful separation of a higher percentage of cells than in previous studies, with a separation efficiency higher than 90%. In the past, there have been no confirmed cases in which a separation rate of over 90% and high-speed processing of a large number of cells were simultaneously achieved. It was shown that the proposed device can process large numbers of cells at high speed and with high accuracy.

Fluffy LDH/GO 2D Membrane for Rapid Removal of Soluble Pollutants and Enhanced Catalytic Self-Cleaning Performance

The rapid expansion of the chemical and pharmaceutical industries has resulted in the introduction of various sources of micropollutants into the environment, posing threats to drinking water quality and public health. Membrane separation technology offers a promising solution with low energy use, high-quality effluent, and operational simplicity. Here, we developed fluffy LDH/GO 2D membranes, specifically tannic acid-mediated LDH-GO/GO-TA composite membranes (LG/GT). The integration of GO nanosheets regulated the growth of LDH, enhancing electron transfer and adsorption-driven catalytic performance. This design enabled LDH-GO to activate peroxymonosulfate (PMS) and completely degraded Rhodamine B (RhB) within 10 min. The Gaussian calculation was combined with this finding, which could explain the catalytic self-cleaning in the separation process. The TA-mediated enhancement further increased the RhB rejection of LG/GT-7.5 to 99.23%. Additionally, the needle/sheet structure significantly improved permeance to 358.28 L m-2 h-1 bar-1, surpassing the L/GT-7.5 performance (e.g. 338.53 L m-2 h-1 bar-1), indicating superior pore formation and water mass transfer. The heterostructure between GO and LDH greatly improved cycling stability, with the membrane maintaining a permeance of 282.71 L m-2 h-1 bar-1 and a rejection of 97.97% despite 20 cycles. This work demonstrated the potential of fluffy layered LDH 2D membranes for enhanced wastewater treatment applications. These findings suggested significant potential for practical implementation in industrial wastewater treatment processes, offering a sustainable and efficient solution to water pollution challenges.

Facile design of a crown ether-functionalized polymeric membrane for highly efficient lithium and magnesium separation during electrodialysis

Efficient separation of magnesium and lithium is essential for the extraction of lithium resources from salt-lake brines. However, the current membrane separation technologies are challenged by the membrane permeability-selectivity trade-off. Herein, we demonstrated a facile and practical approach to fabricate crown ether-functionalized polymeric membranes with excellent Li+/Mg2+ separation performance by incorporating 12-crown-4 rings into the cellulose triacetate polymer network. The tightly and regularly arranged polymer chains anchored the crown ether rings firmly in the membrane structure, thereby facilitating the formation of stable and highly selective cation transport channels inside the membrane. As a result, the prepared membrane achieved an ultrahigh Li+/Mg2+ separation factor of ∼872 and Li+ flux of 22.6 μmol m−2 s−1, which was much superior to that of commercial CIMS and reported membrane separation technologies. The good long-term stability of the fabricated membrane is promising for achieving efficient magnesium-lithium separation in large-scale industrial applications.

Unsteady separation mechanism of ground horizontal-sliding takeoff system

Complex aerodynamic interference has long posed challenges to the safe separation of multi-body systems. Based on a new conceptual ground horizontal-sliding takeoff approach, the rocket sled system, computational fluid dynamics (CFD) simulations are conducted to study the separation between the payload and the rocket booster, with the Advisory Group for Aerospace Research and Development Model B representing the payload. The motion trajectory of the payload and the unsteady interaction flow mechanisms during separation are analyzed by altering the payload's layout, center of gravity (CoG), and sliding Mach number. The results show that positioning the payload closer to the front along the axis increases the likelihood of collisions after separation. At a sliding velocity of Ma=3, the payload tends to exhibit a nose-down attitude when lc/lp&amp;lt;0.64. Conversely, when lc/lp&amp;gt;0.64, the pitching angle becomes excessively large, which increases the risk of stalling or somersaulting. Furthermore, the CoG needs to move forward to reduce the growth rate of the pitching angle when the separation Mach number is increased. These studies can provide valuable references for the development of separation technology for the rocket sled system.

Research Progress on the Extraction and Separation Technology of Rubidium and Cesium Ions

Research Progress on the Extraction and Separation Technology of Rubidium and Cesium Ions

A UV-resistant porous composite film for radiative cooling and enhanced hydrophobicity

Passive Daytime Radiative Cooling (PDRC) offers a promising strategy to reduce surface heat by reflecting solar radiation and emitting long-wave infrared radiation into space. However, the widespread application of PDRC is currently limited by challenges such as complex fabrication processes, high costs, and the materials’ susceptibility to outdoor aging. In this work, we fabricated a cost-effective, ultraviolet (UV)-resistant porous composite (UPC) film by phase separation technology. UPC films achieve high solar reflectance (0.92) and outstanding broadband longwave infrared thermal emissivity (0.975) by adjusting particle size and mass fractions of TiO2 particles embedded in Poly (methyl methacrylate) (PMMA). When applied to a drone, the films achieve a cooling effect of 12.6°C. Notably, the mid-infrared emissivity of UPC films remained stable after prolonged exposure to UV radiation (360 hours at an irradiance of 1 W/m2), with the reflectance decreasing by only 1.3 %. Software simulations were employed to evaluate the energy savings performance of UPC films in various urban environments, showing significant energy-saving benefits. Furthermore, after treatment with the modified solution, the surface contact angle of UPC films reaches 152.5°, providing excellent resistance to contamination. This work contributes to the advancement of low-cost, durable, and energy-efficient cooling solutions.

High-strength, super-hydrophilic alginate electrospun nanofibrous membranes for rapid oil-water emulsion separation

Ultrafiltration membrane separation technology is considered an effective method for separating oil-water emulsions. However, oil droplets can easily deposit on the surface of the membranes, leading to severe fouling and a decrease in flux. In this study, poly (ethylene oxide)/acrylamide/sodium alginate (PEO/AM/NaAlg) hydrogel nanofibers were deposited on a poly (hydroxybutyric acid) (PHB) electrospun nanofibrous membrane. Subsequently, superhydrophilic (ethylene oxide)-poly(acrylamide)/calcium alginate hydrogel nanofiber composite filtration membranes (PEO/PAM/CaAlg-PHB) were prepared by polymerization and Ca2+ cross-linking using a PHB electrospun nanofibrous membrane as the matrix. The morphology, tensile strength, water contact angle, and oil–water emulsion separation properties of the PEO/PAM/CaAlg-PHB hydrogel filtration membrane were investigated. The results showed that the PEO/PAM/CaAlg-PHB membrane had good anti-fouling performance, with a tensile strength of 1.95 MPa. After 3 h of the filtration operation, the stable flux and oil–water emulsion rejection of the membrane reached 2925.2 L m−2 h−1 bar−1 and 98.66 %, respectively. The preparation method was simple, cost effective, and environmentally friendly, without introducing any organic pollutants. The PEO/PAM/CaAlg-PHB hydrogel filtration membrane shows promise for separating oil–water emulsions.

Comparison of Wideband Loss Separation Technology Considering the Impact of Skin Effect

Comparison of Wideband Loss Separation Technology Considering the Impact of Skin Effect

In situ hydrolyzed microporous polymer membranes for additional free volume to facilitate CO2 permeation

Advancements in membrane separation technology play a pivotal role in separation processes closely associated with the environment and energy. However, presently available commercial polymeric membranes encounter the challenge of low permeability, impacting both separation efficiency and membrane module costs. Here, we propose a simple and effective in situ acid hydrolysis strategy to significantly enhance membrane permeability. Specifically, a tetrafluorinated monomer with hydrolyzable Schiff base groups (TFNAD) has been meticulously designed, synthesized, and copolymerized with commercial TFTPN and TTSBI, yielding a series of copolymers. Subsequently, in situ hydrolysis removes aniline from the membrane, freeing up the occupied free volume and creating additional channels for gas transport. This process substantially enhances gas permeability while preserving the desired selectivity. PIM-TFAD-30 showed a 68 % improvement in CO2 permeability with virtually no compromise in CO2/N2 selectivity compared to the pre-hydrolysis membrane. Meanwhile, PIM-TFAD-30 also displayed outstanding separation performance and plasticization resistance in simulated flue gas tests, demonstrating its potential for practical application. This facile and straightforward hydrolysis method opens up a new perspective for preparing and modifying polymeric separation membranes beyond gas separation.

3D Covalent Organic Framework Membranes for Molecular Separations.

Membrane separation has become an indispensable separation technology in social production, playing an important role in drug production, water purification, etc. The key core of membranes lies in achieving efficient and precise sieving between substances. As a result, a typical trade-off arises: highly permeable membranes usually sacrifice selectivity and vice versa. To address this dilemma, long-term research has focused on comprehensive understanding and modelling of synthetic membranes at various scales. A significant advancement in this arena is the advent of three-dimensional covalent organic framework (3D COF) membranes, a novel category of long-range ordered porous organic polymer materials. Characterized by an abundance of interconnected channels, diverse pore wall properties, tunable structures, and robust thermal and chemical resilience, 3D COF membranes offer a promising approach for efficient substance separation. This review undertakes a meticulous investigation of the synthesis and physicochemical properties of 3D COF membranes, accentuating the underlying design principles, fabrication methods, and application attempts. A comprehensive assessment of their research trajectory and current standing in the field of membrane processes is provided. The review culminates in a forward-looking outlook, summarizing future research directions and highlighting the substantial potential of this innovative work to shape the future of efficient membrane separation processes.

Development of cost-effective cellulose-based bilayer hybrid composite membranes for CO2 separation in biogas purification

CO2 is the main pollutant in biogas, reducing its calorific value. Among various technological methods to eliminate carbon dioxide from biogas, membrane separation technology stands out for large-scale industrial biogas purification due to its advantages. The selection of membrane material and preparation process are key factors in membrane separation technology. In this study, a premixing process was initially used to blend different masses of packed molecular sieves TS-1 (or ZSM-5) and cellulose derivatives (ethyl cellulose, cellulose acetate) separately. These mixtures were then coated onto porous PVDF substrates using a coating process to create various bilayer hybrid composite membranes. Among these, PVDF/EC-ZSM-5 (containing 15 % ZSM-5) bilayer hybrid composite membrane is the most fitting. For CO2/CH4 gas mixtures, the gas selectivity of this membrane surpassed Robeson's 1991 standard line (the CO2 permeability was 597.48 Barrer, and the CO2/CH4 selectivity was 9.14). Overall, this composite membrane, made for the first time from PVDF, ZSM-5, and EC, is expected to be a promising CO2 selective separation membrane material for biogas purification in large-scale industrial processes due to its simple production process.