Separation Properties Research Articles

The problem of non-proprietary legal entities in the light of the theory of separate property

The problem of non-proprietary legal entities in the light of the theory of separate property

Cellulose Membranes: Synthesis and Applications for Water and Gas Separation and Purification.

Membranes are a selective barrier that allows certain species (molecules and ions) to pass through while blocking others. Some rely on size exclusion, where larger molecules get stuck while smaller ones permeate through. Others use differences in charge or polarity to attract and repel specific species. Membranes can purify air and water by allowing only air and water molecules to pass through, while preventing contaminants such as microorganisms and particles, or to separate a target gas or vapor, such as H2 and CO2, from other gases. The higher the flux and selectivity, the better a material is for membranes. The desirable performance can be tuned through material type (polymers, ceramics, and biobased materials), microstructure (porosity and tortuosity), and surface chemistry. Most membranes are made from plastic from petroleum-based resources, contributing to global climate change and plastic pollution. Cellulose can be an alternative sustainable resource for making renewable membranes. Cellulose exists in plant cell walls as natural fibers, which can be broken down into smaller components such as cellulose fibrils, nanofibrils, nanocrystals, and cellulose macromolecules through mechanical and chemical processing. Membranes made from reassembling these particles and molecules have variable pore architecture, porosity, and separation properties and, therefore, have a wide range of applications in nano-, micro-, and ultrafiltration and forward osmosis. Despite their advantages, cellulose membranes face some challenges. Improving the selectivity of membranes for specific molecules often comes at the expense of permeability. The stability of cellulose membranes in harsh environments or under continuous operation needs further improvement. Research is ongoing to address these challenges and develop advanced cellulose membranes with enhanced performance. This article reviews the microstructures, fabrication methods, and potential applications of cellulose membranes, providing some critical insights into processing-structure-property relationships for current state-of-the-art cellulosic membranes that could be used to improve their performance.

THE OBLIGATION TO DISCLOSE THE SPOUSE’S SEPARATE PROPERTY IN A MAYOR’S FINANCIAL DISCLOSURE STATEMENT – CRITICAL COMMENTS ON THE DRAFT ACT

The transparency of the assets of persons performing key public functions is desired and expected by the public. However, the current regulations unfortunately do not guarantee it fully. Therefore, on 21 November 2023, a Draft Act Amending the Act on Restrictions on the Conduct of Business by Persons Performing Public Functions and Certain Other Acts was submitted by a group of Sejm members to the Speaker. This bill, commonly referred to as ‘clean hands’, provides for the principle under which the separate property of the spouses of state and local self-government officials will also have to be disclosed in the financial disclosure statements they submit. In the present study, the author analyses the proposed changes and assesses them through the prism of the principles and rights expressed in the Constitution. She also suggests adopting solutions that would effectively prevent the concealment of assets by persons obliged to submit financial disclosure statements.

Preparation of Quaternary Ammonium Separation Material based on Coupling Agent Chloromethyl Trimethoxysilane (KH-150) and Its Adsorption and Separation Properties in Studies of Th(IV).

In this research, the authors studied the synthesis of a silicon-based quaternary ammonium material based on the coupling agent chloromethyl trimethoxysilane (KH-150) as well as its adsorption and separation properties for Th(IV). Using FTIR and NMR methods, the silicon-based materials before and after grafting were characterized to determine the spatial structure of functional groups in the silicon-based quaternary ammonium material SG-CTSQ. Based on this, the functional group grafting amount (0.537 mmol·g-1) and quaternization rate (83.6%) of the material were accurately calculated using TGA weight loss and XPS. In the adsorption experiment, the four materials with different grafting amounts showed different degrees of variation in their adsorption of Th(IV) with changes in HNO3 concentration and NO3- concentration but all exhibited a tendency toward anion exchange. The thermodynamic and kinetic experimental results demonstrated that materials with low grafting amounts (SG-CTSQ1 and SG-CTSQ2) tended to physical adsorption of Th(IV), while the other two tended toward chemical adsorption. The adsorption mechanism experiment further proved that the functional groups achieve the adsorption of Th(IV) through an anion-exchange reaction. Chromatographic column separation experiments showed that SG-CTSQ has a good performance in U-Th separation, with a decontamination factor for uranium in Th(IV) of up to 385.1, and a uranium removal rate that can reach 99.75%.

Dotting Out AML by Targeting Fibrillarin.

Dysregulated biomolecular condensates, formed through multivalent interactions among proteins and nucleic acids, have been recently identified to drive tumorigenesis. In acute myeloid leukemia (AML), condensates driven by RNA-binding proteins alter transcriptional networks. Yang and colleagues performed a CRISPR screen and identified fibrillarin (FBL) as a new driver in AML leukemogenesis. FBL depletion caused cell cycle arrest and death in AML cells, with minimal impact on normal cells. FBL's phase separation domains are essential for pre-rRNA processing, influencing AML cell survival by regulating ribosome biogenesis and the translation of oncogenic proteins like MYC. Therapeutically, the chemotherapeutic agent CGX-635 targets FBL, inducing its aggregation, impairing pre-rRNA processing, and reducing AML cell survival. This highlights FBL's phase separation as a therapeutic vulnerability in AML. These findings suggest that targeting the phase separation properties of RNA-binding proteins could offer a novel and effective strategy for AML treatment. Further research into condensate dynamics in cancer and development of condensate-modulating drugs holds significant promise for future cancer therapies.

Efficient photodegradation of Rhodamine B dye assisted by Pigskin-Gel via sustainable synthesis of Fe2O3@rGO nanocrystals with magnetically separable properties

Efficient photodegradation of Rhodamine B dye assisted by Pigskin-Gel via sustainable synthesis of Fe2O3@rGO nanocrystals with magnetically separable properties

Decarboxylation cross‐linking of fluorescein‐based copolyimides for gas separations

AbstractA fluorescein‐based diamine, 2‐(3,6‐bis(4‐amino‐3‐hydroxyphenoxy)‐9H‐xanthen‐9‐yl) benzoic acid (CADA), was synthesized and copolymerized with Durene and 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to form a 6FDA‐Durene/CADA (3:2) copolyimide. The copolyimide was thermally cross‐linked at 300–425°C to form a series of decarboxylated cross‐linked polyimides. Compared with the 6FDA‐CADA polyimide, the incorporation of Durene diamine increased gas permeability of the pristine and the thermally cross‐linked polyimides greatly. The copolyimide cross‐linked at 375°C showed separation performance to the O2/N2 gas pair beyond the 1991 Robeson upper limit, while the CO2/CH4 separation property of the copolyimide cross‐linked at 425°C (PI‐425) was close to the 2008 Robeson upper limit. Moreover, the anti‐CO2‐induced plasticization property of the 6FDA‐Durene/CADA(3:2) copolyimides was improved by cross‐linking. The copolyimides cross‐linked at 350°C and above were not plasticized at a CO2 pressure up to 30 atm. This study showed that gas transport property of the decarboxylated cross‐linked polyimides could be improved significantly by the incorporation of bulky diamino moiety. The fluorescein‐based copolyimide had great potentials for gas separation applications.

Metal-Organic-Frameworks Based Mixed-Matrix Membranes for CO2 Separation: An Applicable-Conceptual Approach.

A promising class of porous crystalline materials, metal-organic frameworks (MOFs), have recently emerged as a potential material in fabricating mixed matrix membranes (MMMs) for gas separation applications. Their unique chemistry and structural versatility offer substantial advantages over conventional fillers. This review gives an in-depth exploration of MOF chemistry, focusing on strategies to manipulate their adsorption behavior to enhance separation properties. We scrutinize the impact of various MOF-based MMM components, including polymer matrix, MOFs fillers and polymer/filler interface, on the overall gas separation performance. This involves a detailed analysis of key parameters associated with MMM preparation. Additionally, we offer a comprehensive overview of the determining factors in MOF-based MMM development for gas separation, including MOF structure, synthesis, and chemistry. Moreover, the most advances in modification strategies of MOF for CO2 separation, such as a wide variety of hybrid MOFs will be outlined, which opens the door to an improved CO2 separation process. Finally, the gas transport mechanisms of MMMs are thoroughly discussed to understand the factors affecting the gas permeation through the polymer matrix, MOFs and interface between them.

Regulating Fe(III) spin state by anchoring iron on titanium dioxide for enhancing photo-Fenton treatment of tetracycline wastewater

Tetracycline (TC) wastewater can hardly be treated effectively by conventional processes due to its stable chemical structure and its refractoriness to biodegradation. Photo-Fenton technology based on iron-based catalyst exhibits excellent capacity on organic wastewater treatment, but current iron-based catalyst materials exist crucial problems such as slow regeneration of Fe(II) and low utilization of H2O2. In this study, Fe atom was anchored on TiO2 to regulate the spin state of Fe to prepare a new efficient photo-Fenton material. The results showed that the removal of TC by Fe2O3-TiO2(high spin, HS) can reach 94.7%, while the removal of TC by Fe-TiO2(low spin, LS) was only 83.0%. The Fe2O3-TiO2(HS) maintained high photo-Fenton activity after five cycles, and the TC removal rate still reached 91.8%. Fe2O3-TiO2(HS) had a narrow bandgap and excellent photogenerated charge separation properties, which facilitates the generation of photogenerated charges, improves the electron transfer, and accelerates the redox cycle of Fe(III)/Fe(II). The electrons in the 3d orbital of Fe2O3-TiO2(HS) are more easily to cross the antibonding orbital of the H2O2, which is conducive to the adsorption of H2O2 and generation of ·OH to accelerate TC degradation. This study provides a new photo-Fenton material for the treatment of TC wastewater and offers a new strategy for the development of photo-Fenton.

Gas separation in bimetallic Zn/Co-ZIF-62 glass membrane

Metal-organic framework (MOF) glasses, are attracting increasing attention in the gas separation field due to their component flexibility, ease of processing and porous structures. In this work, a series of bimetallic MOF glass membranes were synthesized and the impact of the metal node ratio (Co/Zn) on the gas separation performance of the membranes was investigated. It is found that the replacement of Zn nodes by Co in the ZIF-62 glass membrane leads to a nonlinear increase in the separation selectivity for [Formula: see text] and [Formula: see text]. Such a phenomenon corresponds to the mixed-metal node effect found in the MOF glass. Through the structural characterization results, we found that the different affinities of the central metal nodes towards gas molecules and the diversity in porosity of the Zn/Co-ZIF-62 membranes could be the two main reasons for the evolution of the gas separation properties in the ZIF-62 glass membranes. This work gives a new approach to developing MOF glass membranes with high-performance gas separation.

Enhancing dye/salt separation efficiency through polysulfobetaine-modified poly (triazine imide)/polyethersulfone (PTI-PSBMA/PES) composite membrane fabrication

Membrane technology stands as a vital solution for efficient dye/salt separation in various industrial processes. For the first time in this study, polysulfobetaine-modified poly (triazine imide) (PTI-PSBMA) was simply prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization as an additive for PTI-PSBMA/PES composite membrane preparation using the phase inversion strategy. The SEM, AFM pictures, and WCA analysis results exhibited that the modified membranes with PTI-PSBMA possess smoother surfaces and are more hydrophilic. After conducting an investigation using a dead-end filtration setup, it has been determined that the PTIZ-1 membrane, containing 1.0 wt% of PTI-PSBMA, emerged as the most effective membrane. This membrane exhibited a remarkable water flux of 46.0 L. m−2 h−1 bar−1 and demonstrated the highest rejections for various dyes, such as Reactive Red 120 (92.3 %), Direct Yellow 29 (79.3 %), and Methyl Green (85.0 %). Additionally, the PTIZ-1 membrane displayed impressive antifouling properties, with protein adsorption decreasing by over 96.0 %. With exceptional rejection rates for dyes and high permeability for salts, this composite membrane presents a promising solution for practical applications in wastewater treatment and dye removal processes. This research contributes to advancing membrane technology by introducing a highly efficient composite membrane with enhanced separation properties, addressing critical challenges in industrial dye/salt separation processes.

Self-standing COF-MOF composite sandwich membranes with high permeability for dye separation

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) hybrids are novel porous composite materials with potential applications in advanced membrane separations. However, the preparation of defect-free and self-standing separation membranes remains challenging. Here, we report a COF-MOF composite membrane with a sandwich layer structure and a two-dimensional (2D) intergrown nanosheet morphology. This was achieved by inducing the secondary growth of a layer of MOF (ZIF-67) membrane using a two-dimensional COF (TpPa1) membrane as a seed layer and porous support. It is worth noting that a rare ZIF-67 membrane consisting of 2D nanosheets was grown on the TpPa1 porous support. The [TpPa1]-[ZIF-67] membranes exhibited excellent permeance for organic solvents, pure water (95.3 L m−2 h−1 bar−1), with high rejection rates (>97 %) towards dyes larger than 700 Da, while maintaining a low rejection rate for hydrated salt ions (<14 %) and outstanding dye/salt selectivity. The membranes also displayed considerable long-term operational stability and could be easily transferred to other substrates without damaging their integrity. The excellent separation properties achieved through layer-by-layer filtration are mainly due to the sandwich structure and the synergistic effect of the components.

Sequence dependence of critical properties for two-letter chains.

Histogram-reweighting grand canonical Monte Carlo simulations are used to obtain the critical properties of lattice chains composed of solvophilic and solvophobic monomers. The model is a modification of one proposed by Larson et al. [J. Chem. Phys. 83, 2411 (1985)], lowering the "contrast" between beads of different types to prevent aggregation into finite-size micelles that would mask true phase separation between bulk high- and low-density phases. Oligomeric chains of lengths between 5 and 24 beads are studied. Mixed-field finite-size scaling methods are used to obtain the critical properties with typical relative accuracies of better than 10-4 for the critical temperature and 10-3 for the critical volume fraction. Diblock chains are found to have lower critical temperatures and volume fractions relative to the corresponding homopolymers. The addition of solvophilic blocks of increasing length to a fixed-length solvophobic segment results in a decrease of both the critical temperature and the critical volume fraction, with an eventual slow asymptotic approach to the long-chain limiting behavior. Moving a single solvophobic or solvophilic bead along a chain leads to a minimum or maximum in the critical temperature, with no change in the critical volume fraction. Chains of identical length and composition have a significant spread in their critical properties, depending on their precise sequence. The present study has implications for understanding biomolecular phase separation and for developing design rules for synthetic polymers with specific phase separation properties. It also provides data potentially useful for the further development of theoretical models for polymer and surfactant phase behavior.

Liquid gated membrane with self-cleaning properties for controllable removal and multi-component separation of organic/bacterial contaminants

Membrane technology plays an important role in sustainable water treatment; however, the non-adjustable pores make it difficult to achieve precise molecular separation, and membrane fouling remains a challenge in membrane processes. Herein, a smart liquid gated membrane (LGM) was prepared by filling different lubricants in the micropores of PET track-etched membrane that was pre-treated with nano roughening and fluorination. When the pressure exceeds a critical breakthrough pressure, the liquid lined pores are formed, and higher gating liquid/water interfacial tension requires higher pressure to break through the gate. The effective pore size of LGM increases with increasing pressure. When the pressure is removed, the liquid refilling that leads to pore-closing is promoted by lower lubricant viscosity and larger effective pore size. Through the tunable permeability, controllable removal and multi-component separation of organic/bacterial contaminants can be achieved. The maximum rejection for protein approaches 94 %; as the pressure increases, three components are separated in the order of pectin, soy protein isolate and Staphylococcus aureus with maximum separation coefficient of 56.7. Due to the stable lubricant lining, LGM shows excellent self-cleaning performance with much higher flux recovery rate than the non-lubricated membranes. This liquid gated membrane has great application prospects in size-fractionated separation and product recovery.

NaAlO2/CuFe2O4 as a novel basic magnetic heterogeneous catalyst for effective biodiesel production: Synthesis, characterization, and optimization via RSM-FCCD modeling approach

This research focus on the development of a novel and superior basic magnetic heterogeneous catalyst, using NaAlO2 as an active species supported in CuFe2O4 to produce biodiesel. Thus, a series of catalysts have been synthesized by means of conventional and low-cost methods. The features of catalyst have been elucidated through techniques such as basicity, XRD, FTIR, SEM, EDS, TG/DTG and VSM. To optimize the biodiesel’s ester content, the face-centered central composite design with the response surface methodology, was employed to assess the effect of the aspects on the process: reaction temperature, MeOH:oil molar ratio, catalyst dosage and time. The regression model presented R2 = 0.9394 and experimentally reached a maximum ester content of 95.9 % attributed to the biodiesel attained under the optimal reaction conditions: temperature of 95.0 °C, MeOH:oil molar ratio of 13:1, catalyst dosage of 8.0 % and time of 60.0 min. The catalyst presented a stable catalytic performance during four transesterification cycles (>90.0 %) and an efficient magnetic property for the catalyst separation and recovery process (Ms = 23.62 emu g−1). The biodiesel’s physicochemical properties were in compliance with ASTM D6751 standard. Finally, this extensive study reveals the basic magnetic heterogeneous catalyst as a practical and promising alternative to produce a sustainable biofuel.

A highly effective arsenic catcher for removing raw water from shale gas-Cucurbit[7]uril modified magnetic biochar

Shale gas is a low-carbon, clean, and high-reserve natural gas resource, but the development process requires a large amount of fresh water and chemicals, which can lead to a large amount of As3+ in the shale gas raw water. The removal of As3+ from shale gas raw water is necessary because of the serious hazards that As3+ can cause once it enters the human body. In this study, a loofah biocarbon material (CBMM) co-modified by Cucurbit[7]uril (CB[7]) and Fe3O4 was prepared. The successful synthesis of the materials was verified by various characterization methods. The material possesses excellent magnetic separation properties and can achieve rapid recovery within 50 s. The adsorption process is spontaneous and endothermic, and the experimental data have excellent correlation with pseudo-first-order kinetic (R2 > 0.99) and Langmuir model (R2 > 0.99). The maximum adsorption capacity of CBMM was 76.43 mg/g at 20 °C. In addition, CBMM still possessed 74.8 % of the initial adsorption capacity after 7 cycles of the experiment. CBMM also had excellent As3+ removal efficiency (90.1 %) in the study of actual shale gas raw water. In conclusion, CBMM is a very promising adsorbent for the removal of As3+ from shale gas raw water.

Computational design of novel highly connected COFs for CH4/H2 adsorption and separation

Ten new highly connected cubic boronitrate (-B4N4O12-) base covalent organic frameworks (BN-COFs) were designed in the lta and aco topologies. These structures were optimized and characterized computationally using density functional theory (DFT) and molecular mechanics methods. The structural characterization reflects that these BN-COFs possess the appropriate structural parameters for CH4/H2 adsorption and separation, such as low density (0.52–1.28 g·cm−3), high pore porosity (22 %-72 %), appropriate pore limiting diameter (PLD, 2.45–6.71 Å) and the largest cavity diameter (LCD, 3.21–19.96 Å), large pore volume (0.15–1.37 cm3·g−1) and accessible surface area (332–3974 cm2·g−1). Grand canonical Monte Carlo (GCMC) simulations were conducted to investigated the adsorption and separation properties of CH4 and H2 in ten BN-COFs. The results indicate that the uptake capacity of methane and hydrogen in BN-COF-5, −9 and −10 has exceeded the targets set by the U.S. Department of Energy (DOE). Furthermore, the CH4/H2 selectivity of ten BN-COFs is comparable to that of typical porous materials. The outstanding CH4/H2 adsorption and separation properties of these BN-COFs can provide some references and inspirations for researchers to develop high-performance porous adsorbents in experimental studies.

In situ oxidation of reduced graphene oxide membranes by peracetic acid for dye desalination

Graphene oxide (GO) membranes with tunable interlayer spacings are of interest for dye removal from salty textile wastewater, and the membranes are often reduced to improve their stability, which inevitably lowers water permeance. Herein, we demonstrate that reduced GO (rGO) membranes can be facilely modified using peracetic acid (PAA) in situ to dramatically enhance water permeance while retaining dye rejection. Specifically, PAA-modified membranes (PrGO) are synthesized by vacuum-filtering hydrazine-reduced rGO nanosheets onto Nylon substrate and then exposing them to PAA solutions. The effects of the rGO layer thickness, PAA content, and PAA exposure time on the membrane chemistry, nanostructures, and salt/dye separation properties are thoroughly examined. For example, the PAA oxidation of a 100 nm-thick rGO membrane for 10 min increases water permeance by 180 %, from 35 to 93 Liter m−2 h−1 bar−1, and decreases Na2SO4 rejection from 10 % to 3.3 % while retaining the rejection of Congo red at ≈99.7 %. The PrGO membranes exhibit stable water permeance and >99 % dye rejection in multi-cycle tests in a crossflow system, surpassing state-of-the-art GO membranes and showcasing their potential for practical applications.

Influence of dangling chains on the microphase separation and damping properties of polyurethane

AbstractUnderstanding how dangling fragments of polyurethanes (PU) affect its microphase separation structure and damping properties can provide insights for designing desired materials at the molecular scale. By varying the types of diol extenders (such as 1,2‐ethyleneglycol, 1,2‐propanediol, and 1,2‐butanediol), PU samples with different dangling residues were successfully synthesized. Using atomic force microscopy and small‐angle x‐ray scattering, we confirmed that the introduction of dangling chains disrupts microphase separation and demonstrated a correlation between the degree of suppressed microphase separation and the size of the dangling residues. Fourier transform infrared spectroscopy and molecular dynamics simulations confirmed that dangling chains reduce the hydrogen bonding index while increasing the phase compatibility between soft and hard segments. Differential scanning calorimetry (DSC) measurements revealed an increased glass transition temperature (Tg), indicating hindered movement of backbone segments due to dangling chains. Moreover, lengthening the dangling chains further decreased Tg. Dynamic mechanical analysis (DMA) demonstrated improved damping properties with the introduction of dangling chains, although increasing chain length led to deteriorating damping properties, consistent with observations from DSC. These findings suggest that the variations in macroscopic properties of PU induced by dangling chains are linked to hydrogen bonding interactions and micromorphology at the molecular level.

Emulsified oil-water separation properties of superhydrophobic/superoleophilic surface by emulsion droplets impacting dynamic behavior

Superhydrophobic/superoleophilic materials with excellent separation property are urgently needed for the clarification of water from oil-water emulsions, however, the lack of interfacial contact dynamics in the separation process is not beneficial to extensive application for them. Herein, a superhydrophobic/superoleophilic mesh was successfully prepared by spraying fluorinated polyurethane (FPU), silicon dioxide (SiO2) and carbon nanotubes (CNTs). The prepared mesh exhibited excellent superhydrophobic/superoleophilic performance, accomplishing a 1636.9 L m−2h−1 flux and a high separation efficiency above 99.8 % for water-in-oil (W/O) emulsions. The dynamic behavior of emulsion droplets impacting on the prepared mesh was innovatively investigated by experiment and simulation. As the oil content of emulsion droplets increased from 0 wt% to 2 wt%, the maximum spreading diameter (Ddmax) of emulsion droplets decreased from 5.57 mm to 5.28 mm, which can be attributed to the oil capture ability of the superhydrophobic/superoleophilic surface. Simultaneously, the maximum jet height (Hdamx) and the retraction velocity of the droplets firstly decreased and then increased. The results revealed that the oil film captured on the surface possessed good lubricity and water repellency, which could accelerate the dislodging of water from the surface and enhance separation performance. The separation mechanism of superhydrophobic/superoleophilic surface revealed by the contact dynamics study provided a novel path for the fabrication of emulsified oil-water separation materials.