Separation Technology Research Articles

Macrocyclic Chiral Two‐Dimensional Membranes for Enantiomers Separation

AbstractChiral enantiomers, while typically exhibiting similar physical and chemical properties, often have distinct therapeutic effects. The preparation of pure enantiomers is therefore of significant interest in the food, chemical, and pharmaceutical industries, making the separation of enantiomers highly sought after. Membrane separation technology has garnered widespread attention for its environmental friendliness and scalability. Recently, chiral two‐dimensional (2D) membranes have demonstrated superior separation performance due to their ultrathin nature and orderly transmission channels. Macrocyclic chiral 2D membranes, in particular, combine the inherent cavity structure of macrocyclic molecules with the host‐guest interaction capabilities that specifically recognize chiral molecules. Additionally, they benefit from the excellent chemical stability and adjustable interlayer spacing of 2D materials. This combination allows these membranes to achieve high enantioselectivity while improving flux. By optimizing the trade‐off between flux and enantioselectivity, this strategy offers a promising new approach for developing advanced chiral membranes.

Perfusion Process Intensification for Lentivirus Production Using a Novel Scale-Down Model.

Process intensification has become an important strategy to lower production costs and increase manufacturing capacities for biopharmaceutical products. In particular for the production of viral vectors like lentiviruses (LVs), the transition from (fed-)batch to perfusion processes is a key strategy to meet the increasing demands for cell and gene therapy applications. However, perfusion processes are associated with higher medium consumption. Therefore, it is necessary to develop appropriate small-scale models to reduce development costs. In this work, we present the use of the acoustic wave separation technology in combination with the Ambr 250 high throughput bioreactor system for intensified perfusion process development using stable LV producer cells. The intensified perfusion process developed in the Ambr 250 model, performed at a harvest rate of 3 vessel volumes per day (VVD) and high cell densities, resulted in a 1.4-fold higher cell-specific functional virus yield and 2.8-fold higher volumetric virus yield compared to the control process at a harvest rate of 1 VVD. The findings were verified at bench scale after optimizing the bioreactor set-up, resulting in a 1.4-fold higher cell-specific functional virus yield and 3.1-fold higher volumetric virus yield.

Spatial magnetic force and magnetic energy density analysis of microsphere medium in high gradient magnetic fields: A 3D simulation

Abstract High gradient magnetic separation technology is the key technology for green and efficient separation and purification of mineral resources. Existing studies are vague about the division of the attraction and repulsion zones of the medium, and there are fewer explorations of the effect of various conditions on the attraction zones. In this work, a novel method for calculating the magnetic force is derived, which provides an accurate calculation of the 3D magnetic force. The attraction and repulsion zones are divided clearly by analyzing the relationship between the spatial angle of the spherical medium and the magnetic force density per unit volume, with the magnetic force density per unit volume tangent to the spherical surface as the dividing line. The attraction and repulsion zones are divided by β = 30°~35°, and the attraction region accounts for 45%~50% of the total space volume. Furthermore, the influence of different conditions on the attraction zone is studied. It was found that the zone of attraction decreases as one moves away from the spherical medium, which results in an ellipsoid with the effective zone of attraction of the spherical medium having the magnetic field direction as its long axis. The attraction region increases from 45.49% to 49.87% of the space occupied with increasing the relative permeability of the spherical medium. It does not affect the proportion of the attraction zone in space by changing the background magnetic field and the size of the spherical medium, but it will change the depth of the magnetic force. It provides a theoretical basis for the design of high-efficiency magnetic media, and gives a reference for further improving the selection effect of high gradient magnetic separation technology on fine and weak magnetic particles.

Laser-based disassembly of end-of-life automotive traction batteries: A systematic patent analysis

Battery recycling is a vital component in the decarbonization of the transportation sector. The disassembly step represents a pivotal element within the process chain for battery recycling, as it paves the way for subsequent steps. Semi-destructive disassembly technologies will be key to developing efficient disassembly processes for end-of-life automotive traction batteries. Laser-based separation technologies have emerged as a promising emerging technological approach. Following a systematic search in multiple databases, the obtained records underwent a comprehensive descriptive analysis in terms of both regional and historical context, while key inventors and assignees were identified. Furthermore, citation networks have been identified to provide an overview of the patent landscape and the interrelations within this field. Moreover, an analysis concerning the International Patent Classification and the Cooperative Patent Classification was conducted. An in-depth analysis of relevant patents provides insights into the specific techno-strategic elements currently pursued. The study yields an implication and recommendation framework for research, industry, and policy makers to drive the industrialization of laser-based disassembly technologies as an avenue for efficient end-of-life automotive traction battery disassembly of the future. This framework enables relevant stakeholders to drive their techno-strategic developments in the field of laser-based disassembly, resulting in enhanced laser-based semi-destructive disassembly technologies.

Fluorinated Squareimines for Molecular Sieving of Aromatic over Aliphatic Compounds

The development of more energy‐efficient separation technologies is essential. Especially the separation of cyclic aliphatic hydrocarbons from their aromatic counterparts remains a significant challenge due to azeotrope formation and similar physical properties, often requiring energy‐intensive processes. Herein, we introduce a novel class of electron‐deficient macrocycles with a unique rectangular structure to optimise π···π interactions within the pore, enabling the highly selective molecular sieving of aromatic compounds from mixtures. Utilising dynamic covalent imine chemistry, the squareimine NDI2F42‐based crystalline functional material is directly obtained from the reaction mixture in a single self‐assembly step in high yields of 84%, alongside the larger NDI2F82 congener, which can be obtained in 69% yield. In vapour sorption and diffusion experiments, NDI2F42 demonstrates rapid adsorption kinetics with selectivities of 97:3 for benzene over cyclohexane and 93:7 for toluene over methylcyclohexane, while single‐crystal and powder X‐ray diffraction studies confirm that the selectivity is primarily governed by directed π···π interactions.

Janus channel of membranes enables concurrent oil and water recovery from emulsions.

Existing separation technologies struggle to recover oil and water concurrently from surfactant-stabilized emulsions to achieve the goal of near-zero liquid discharge. We present a Janus channel of membranes (JCM) that features a confined architecture constructed of a pair of hydrophilic and hydrophobic membranes, which allows for concurrent, highly efficient recovery of oil and water from surfactant-stabilized emulsions. The confined Janus channel can amplify the interplay of the membrane pair through a feedback loop that involves enrichment and demulsification. Our JCM achieves exceptional oil and water recoveries of up to 97 and 75%, respectively, with near 99.9% purities. Moreover, its versatility in handling diverse emulsions may enable near-zero liquid discharge for a range of separations.

Fluorinated Squareimines for Molecular Sieving of Aromatic over Aliphatic Compounds.

The development of more energy-efficient separation technologies is essential. Especially the separation of cyclic aliphatic hydrocarbons from their aromatic counterparts remains a significant challenge due to azeotrope formation and similar physical properties, often requiring energy-intensive processes. Herein, we introduce a novel class of electron-deficient macrocycles with a unique rectangular structure to optimise π···π interactions within the pore, enabling the highly selective molecular sieving of aromatic compounds from mixtures. Utilising dynamic covalent imine chemistry, the squareimine NDI2F42-based crystalline functional material is directly obtained from the reaction mixture in a single self-assembly step in high yields of 84%, alongside the larger NDI2F82 congener, which can be obtained in 69% yield. In vapour sorption and diffusion experiments, NDI2F42 demonstrates rapid adsorption kinetics with selectivities of 97:3 for benzene over cyclohexane and 93:7 for toluene over methylcyclohexane, while single-crystal and powder X-ray diffraction studies confirm that the selectivity is primarily governed by directed π···π interactions.

Steering diffusion selectivity of chemical isomers within aligned nanochannels of metal-organic framework thin film

The movement of molecules (i.e. diffusion) within angstrom-scale pores of porous materials such as metal-organic frameworks (MOFs) and zeolites is influenced by multiple complex factors that can be challenging to assess and manipulate. Nevertheless, understanding and controlling this diffusion phenomenon is crucial for advancing energy-economic membrane-based chemical separation technologies, as well as for heterogeneous catalysis and sensing applications. Through precise assessment of the factors influencing diffusion within a porous metal-organic framework (MOF) thin film, we have developed a chemical strategy to manipulate and reverse chemical isomer diffusion selectivity. In the process of cognizing the molecular diffusion within oriented, angstrom-scale channels of MOF thin film, we have unveiled a dynamic chemical interaction between the adsorbate (chemical isomers) and the MOF using a combination of kinetic mass uptake experiments and molecular simulation. Leveraging the dynamic chemical interactions, we have reversed the haloalkane (positional) isomer diffusion selectivity, forging a chemical pathway to elevate the overall efficacy of membrane-based chemical separation and selective catalytic reactions.

Pathways to Carbon Neutrality in Civil Engineering

Abstract. With the development of the global economy and trade exchanges worldwide, urban infrastructure and industrial development have become part of the competition among countries. However, the construction industry and the production of chemical materials emit a large amount of carbon dioxide, leading to the continuous deterioration of the environment, so it is necessary to effectively reduce emissions. As a synonym for global emission reduction, carbon neutrality plays an important role in different industries, especially in civil engineering. In this paper, we start with building materials and green construction to explore the realization of carbon neutrality at the source and center of carbon emission in civil engineering. Firstly, we introduce the low-carbon production technologies of cement and steel, including calcium recycling and membrane separation technology in the cement industry, high-temperature combustion technology and carbon capture technology in steel industry. Then, we take renewable concrete as an example to discuss the emission reduction path of green building materials. Finally, it outlines how to carry out green construction, introduces assembly carbon reduction technology and energy integration system, and demonstrates the possibility of this green construction program in the case of "T&A House".

Preparation of hydrophilic PVDF membranes through in situ assembly of phytate-polyethyleneimine-Fe3+ for efficient separation of herbal volatile oil from oily water.

In the realm of oil-water separation technologies, membrane-based separation emerges as an efficacious approach. Nevertheless, crafting a hydrophilic membrane capable of effectively segregating herbal volatile oil remains a formidable challenge. Our study introduces a facile in situ assembly strategy for fabricating a double-crosslinked composite coating comprising phytate (PA)-polyethyleneimine (PEI) polyelectrolyte complexes and PA-Fe3⁺ assemblies. The PA within the PA-PEI/Fe3⁺ coatings form a double cross-linking layer through interactions with amine groups and metal ions, thereby enhancing interfacial interactions and structural integrity of the membranes. Consequently, the resultant PVDF/PA-PEI/Fe3⁺ membranes exhibit improved coating stability, pronounced hydrophilicity, and exceptional antifouling capabilities, rendering them highly suitable for the separation of diverse herbal volatile oil-in-water emulsions. Furthermore, they possess the capability for reuse with an average retention ratio exceeding 90% and a pure water flux reaching up to 3200 L·m⁻2·h⁻1. Additionally, they demonstrate long-term stability and resistance to corrosion. With a simplistic yet efficient preparation process, the PVDF/PA-PEI/Fe3⁺ membrane holds significant potential for the extraction of oils from herbal volatile oil-in-water emulsions.

Sustainable Solutions in Gas Separation: Exploring the Potential of Deep Eutectic Solvents

In the face of escalating environmental concerns, particularly related to greenhouse gas emissions, this study delves into the potential of Deep Eutectic Solvents (DESs) as a sustainable alternative in gas separation technologies. Focusing on the significant emissions of CO2, SO2, and H2S from industrial processes, this work reviews the application of DESs for their capture and separation. We investigate the physical properties of DESs, such as solubility and viscosity, which are crucial for their efficacy as sorbents. This review includes a comprehensive analysis of various DES formulations, exploring their roles in CO2 absorption, SO2 removal, and the separation of other gases like H2S. Additionally, we extend our examination to the applicability of DESs in the oil and gas industry, highlighting their effectiveness in removing sulfur and nitrogen impurities, and their potential in the extraction of organic constituents. The study reveals that DESs, characterized by their biodegradability and environmental sustainability, offer promising performance in gas separation, aligning with the principles of green chemistry. However, challenges such as high viscosity and the need for further understanding of their solubility dynamics under different conditions are addressed. This work underscores the importance of DESs as novel sorbents for gas purification and sets a foundation for future research aimed at enhancing their application on a broader industrial scale.

The Role of Nanoporous Adsorbents in the Circular Economy—Closing the Loop of Critical Materials Recovery

AbstractDue to the increase in the global population, industrialization, and the transition to climate neutrality through low‐emission technologies, the pressure on critical materials (CMs) continues to grow. CMs are defined as materials with a significant risk of supply chain disruption and limited substitutability. In this context, rare‐earth elements, platinum group metals, lithium, and cobalt are particularly crucial for the shift to carbon‐free economy and sustainability. One of the important strategies to endorse the goal of carbon reduction is to promote the recycling of resources. As a solution, effective recovery strategies have been developed, such as solid‐phase separation technologies based on advanced functional sorbents. This perspective article aims to provide a general assessment of the role of porous materials in closing the loop of critical materials recycling. Here, comprehensive insights are provided into recent development, design, and application of porous adsorbents commonly applied in solid‐phase extraction systems. Their current research status and problems related to their future application are also highlighted. This review covers recent advances in porous and hierarchical silica‐based materials, aerogels, covalent organic frameworks, metal–organic frameworks, and carbon‐based adsorbents.

Experimental and Numerical Studies of the Temperature Field in a Dielectrophoretic Cell Separation Device Subject to Joule Heating.

Technologies for rapid and high-throughput separation of rare cells from large populations of other types of cells have recently attracted much attention in the field of bioengineering. Among the various cell separation technologies proposed in the past, dielectrophoresis has shown particular promise because of its preciseness of manipulation and noninvasiveness to cells. However, one drawback of dielectrophoresis devices is that their application of high voltage generates Joule heat that exposes the cells within the device to high temperatures. To further explore this problem, this study investigated the temperature field in a previously developed cell separation device in detail. The temperature rise at the bottom of the microfluidic channel in the device was measured using a micro-LIF method. Moreover, the thermofluidic behavior of the cell separation device was numerically investigated by adopting a heat generation model that takes the electric-field-dependent heat generation term into account in the energy equation. Under the operating conditions of the previously developed cell separation device, the experimentally obtained temperature rise in the device was approximately 20 °C, and the numerical simulation results generally agreed well. Next, parametric calculations were performed with changes in the flow rate of the cell sample solution and the solution conductivity, and a temperature increase of more than 40 °C was predicted. The results demonstrated that an increase in temperature within the cell separation device may have a significant impact on the physiological functions of the cells, depending on the operating conditions of the device.

Hydrodynamic investigation of a novel ultra-capacity tray, using centrifugal and inertial separation technologies

Hydrodynamic investigation of a novel ultra-capacity tray, using centrifugal and inertial separation technologies

Optimization analysis of the particle focusing and separation parameters of a sheathless microfluidic device using standing surface acoustic waves

Flow-based particle separation usually requires a sheath flow for particle manipulation. Sheath fluid is a specialized buffer solution that directs the alignment of particles or cells into the center of the stream. By utilizing sheath flow, the particles or cells can be focused on the middle line of the microchannel, where they can be individually analyzed. However, the method requires an additional design for creating a suitable sheath flow. Purity and separation efficiency may also be influenced by the sheath flow. In this study, we present a sheathless device for particle focusing and separation using standing surface acoustic waves (SSAWs). The device comprises two regions: the focusing and separation regions. In the focusing region, particles in a continuous flow are aligned in the middle of the microchannel by SSAWs; in the separation region, tilted-angle SSAW-based particle separation is used to control particle migration. Varying particle sizes were focused in the focusing region and then separated in the separation region in the sheathless device. Experiments and simulations were also utilized to optimize a sheathless device. 10 and 20 μm particle focusing and separation were conducted in a sheathless device for the first time. We demonstrate that the separation of particles with a diameter of 10 and 20 μm has 90.8 ± 1.75% and 99.5 ± 0.8% separation efficiency, and 98 ± 3.4 and 97.9 ± 0.9% purity. Compared with other focusing and separation technologies, our device can also provide high purity, high separation efficiency, and high device density.

High performance loose-structured membrane enabled by rapid co-deposition of dopamine and polyamide-amine for dye separation

Textile wastewater poses a significant environmental challenge that demands effective treatment. Membrane separation offers a promising solution, with high-flux tight ultrafiltration membranes recognized as an effective technology for dye separation. Polyamide amine (PAMAM), a dendritic macromolecule renowned for its regular structure, high monodispersity, excellent solubility, and tunable molecular weight, has emerged as a promising material for membrane fabrication. This study introduces a novel, eco-friendly, and time-efficient method for preparing polymer composite membranes through one-step co-deposition of dopamine (DA) and PAMAM, predominantly utilizing Michael addition and Schiff base reactions. The incorporation of ammine-rich PAMAM imparts ultra-high hydrophilicity to the membranes (contact angle of 38°), facilitating strong adhesion of water molecules to the membrane surface. The effects of co-deposition time and concentrations of DA and PAMAM on the separation performance of the resulting membranes were systematically investigated. Notably, the optimal membrane demonstrated a high water flux (126.1 L m-2h−1 bar−1), primarily due to the incorporation of PAMAM, which resulted in a looser selective separation layer. Furthermore, the membrane demonstrated excellent rejection of methyl blue (MB) at 98.9 % and low rejection os methyl orange (MO) at 13.2 %, making it well-suited for the selective separation of mixed dyes. Our approach offers a sustainable and technologically advanced solution for addressing resource recovery from textile wastewater.

Simulation and optimisation of vacuum (pressure) swing adsorption with simultaneous consideration of real vacuum pump data and bed fluidisation

Pressure swing adsorption (PSA) is a promising technology for gas separation and purification, receiving considerable attention in the past decades. Existing studies on simulating PSA involving a vacuum pump, the vacuum (pressure) swing adsorption [V(P)SA] process, typically estimate vacuum pump energy consumption using an approximate constant energy efficiency or an empirical energy efficiency correlation, leading to inaccurate representation of realistic vacuum pump performance. In this work, we propose an enhanced computational approach for simulation and optimisation of V(P)SA processes through simultaneous incorporation of realistic vacuum pump performance prediction models and adsorption bed fluidisation limits. The vacuum pump prediction models are developed using data-driven modelling techniques with realistic vacuum pump performance data. The enhanced computational approach more accurately accounts for the V(P)SA performance, without relying on an estimated vacuum pump efficiency and assumed pressure/flow rate boundary conditions at the vacuum pump end of the adsorption bed. Furthermore, this approach prevents the bed fluidisation. The computational results show that the developed prediction models accurately represent the actual performance curves of the vacuum pump. It is also demonstrated that incorporating the vacuum pump prediction models and fluidisation constraints in PSA optimisation leads to significantly different optimal solutions compared to when these factors are not considered.

Superhydrophobic poly(lactic acid) membrane prepared with the induction of modified carbon dots for efficient separation of water-in-oil emulsions

Superhydrophobic separation membranes are considered to be one of the most promising technologies for oil-water separation. However, the plastic waste generated from discarded membranes poses a challenge to the preparation of degraded superhydrophobic separation membranes for achieving eco-friendly separation. In this study, superhydrophobic poly(lactic acid) (PLA) membranes were fabricated using a non-solvent induced phase separation method assisted by l-cysteine modified carbon dots (Cys-CDs). The synergistic effect of Cys-CDs-induced crystallization behavior of PLA and the phase separation process results in the evolution of the surface of the PLA-based membrane from a pistil-like structure to a multi-level micro-nano structure composed of dense lamellar nanofibers and microspheres with an increase in Cys-CDs content. At a Cys-CDs content of 5 wt%, the surface roughness of PLA-based separation membrane reached its maximum, and the water contact angle was as high as 159°. Remarkably, the superhydrophobic Cys-CDs/PLA membrane exhibited promising performance in the separation of water-in-oil emulsions, with a rejection rate of 99.98 % and a flux of 315.74 L·m−2·h−1·bar−1. Additionally, the superhydrophobic Cys-CDs/PLA separation membrane also demonstrates impressive properties such as acid-alkali resistance and rapid recycling into high-value chemicals. Consequently, this rapidly recoverable superhydrophobic porous Cys-CDs/PLA membrane shows great potential for practical applications in actual oil-water separation.

Size-based separation of fine mineral particles using inertial microfluidics: A case of jarosite and anglesite

Many metal phases in industrial hazardous waste coexist as fine mineral particles (FMPs, with particle sizes of 0.01 μm–10 μm) in a physical mixture, making conventional methods unable to achieve separation. Advanced microfluidics has demonstrated its potential in the separation of FMPs, as exemplified by jarosite and anglesite. Our study innovatively proposed an inertial microfluidic method for the separation of FMPs by force difference in curved microchannels, thus produced two distinct migration behaviors and subsequent separation. In addition, the computational fluid dynamics (CFD) simulation model was constructed to predict and analyze the migration behavior and separation trend of FMPs through flow field simulation and particle trajectory tracking. The results indicated that 2.1 μm and 3.6 μm small particles migrated to the outer outlet of the microchannel due to the dominant Dean vortex force, while 7.2 μm and 9.4 μm large particles migrated to the inner outlet relying on inertial focusing. At a flow rate of 1.2 mL/min, the separation efficiency of 3.6 μm jarosite and 9.4 μm anglesite has achieved a leap from 0 % to 60.7 %. This discovery provided feasibility and insights into the application of microfluidic technology for particle separation, and offered enormous potential for practical iron residue treatment.

Fabrication of LTA Zeolite Core and UiO-66 Shell Structures via Surface Zeta Potential Modulation and Sequential Seeded Growth for Zeolite/Polymer Composite Membranes

Zeolite-based polymer composites have garnered significant attention for their applications in separation, catalysis, and energy storage, owing to the unique properties of zeolites. The development of core–shell structures provides a promising strategy to enhance these properties, enabling the fine-tuning of zeolite characteristics within composite films. In this study, we present an innovative approach that leverages surface zeta potential differences to facilitate the growth of an organophilic metal–organic framework (MOF) on hydrophilic zeolite surfaces. Specifically, UiO-66 was successfully attached and grown on Linde Type A (LTA) zeolite particles, resulting in the formation of a robust core–shell structure (LTA@UiO-66). This core–shell architecture significantly minimized interfacial voids when embedded into a polyimide (PI, Matrimid® 5218) matrix, yielding composite films (LTA@UiO-66/PI) with superior mechanical integrity and enhanced gas-separation performance. The LTA@UiO-66/PI films demonstrated remarkable ideal selectivity for O2/N2 (10.7) and CO2/CH4 (47), outperforming traditional LTA/PI composites. These enhancements are attributed to the synergistic effects between the LTA core and the UiO-66 shell, which preserve the molecular sieving capability of the zeolite while ensuring strong adhesion and a void-free interface with the polymer matrix. The findings underscore the significant potential of zeolite-based core–shell structures in advancing industrial applications, particularly in the domains of sustainable gas separation and purification technologies.