Selective Separation Research Articles

Development of a highly stable indium-tin alloy cathode system for enhanced selective separation of europium/dysprosium fission products in molten chloride

Developing efficient and stable cathode materials for separating actinides and rare earth fission products is essential for constructing an integrated fast reactor with a closed actinide cycle. This study developed a multicomponent liquid indium-tin (In-49.1 wt% Sn eutectic) alloy cathode (Tm = 393 K) composed of low-melting-point metals. Through the integration of various electrochemical testing methods and characterization techniques, we systematically investigated the electrochemical behaviors of dysprosium (Dy) and europium (Eu) on liquid indium and indium-tin alloy cathodes, the mechanisms of underpotential deposition, and the thermodynamic properties of the In-Sn-Dy/Eu multicomponent alloy system. The thermodynamic enhancement and selective separation mechanisms for the electrolytic separation of Eu and Dy were elucidated. In the LiCl-KCl-DyCl3-EuCl3 quaternary molten salt system, the extraction efficiency (ηDy) of Dy and the separation factor (SFDy/Eu) between Dy and Eu on the In-Sn alloy cathode reached 99.46 % and 479, respectively. Compared to the indium cathode, the In-Sn alloy cathode improved the extraction efficiency of Dy by 3.21 %. In contrast, the separation factor between Dy and Eu was enhanced by nearly 4.2 times. XRD and XPS results indicate that Dy was extracted on the In-Sn alloy cathode in the form of the intermetallic compound Dy(In0.5Sn0.5)3, while the majority of Eu remained in the molten salt in multiple valence states (Eu(III) and Eu(II)).

Physicochemically modified polymer-based fluidic gates with tunable wetting properties for intelligent liquid manipulations

The creation of a selective flow path and the regulation of a flow rate are of critical importance for polymer-based devices that manipulate liquid at the microscale. The formation of a 3D interconnected network of voids (i.e., physical volumetric modification) and the addition of a nonionic surfactant, Silwet L-77, (i.e., chemical volumetric modification) are expected to affect the wetting properties of polymers, thereby achieving selective gating effect in the polymer-based devices as an appropriate technology. Here, a set of polydimethylsiloxane (PDMS)-based fluidic gates (F-gates) were developed to enable selectivity for liquids and flow-rate control of the liquids by tuning the wetting properties of PDMS with the physicochemical volumetric modifications. For water and oil with different surface tensions (STs), the effects of the physical and chemical volumetric modifications on the fluidic gating of PDMS were quantitatively characterized in terms of contact angle, mass flow rate, and liquid absorption speed. The applicability of PDMS-based F-gates to the selective separation of oil and water even from oil-in-water emulsion was demonstrated by fabricating Janus PDMS-based F-gates. Our physicochemical volumetric modifications were also extensively analyzed to examine whether they satisfy the technological, economic, and ecological requirements of appropriate technology. This is the first effort to tailor the wetting properties of PDMS through physicochemical volumetric modifications, thus configuring a set of PDMS-based F-gates that act both as a separator for liquids of different STs and as a switch for fluid flows.

Development of a Non-Covalent Molecularly Imprinted Polymer via Precipitation Method for the Selective Separation of D-Xylose From Sugarcane Residues.

The agro-industry generates substantial waste, necessitating eco-friendly solutions. This study introduces a novel molecularly imprinted polymer (MIPs) for the selective separation of D-xylose from sugarcane residues. A non-covalent imprinted polymer was synthesized via precipitation and optimized through D-xylose adsorption assays. The polymer demonstrated an Imprinting Factor of 3.34, adsorption equilibrium within 30min, notable reusability retaining over 95% of its adsorption capacity after three cycles, and high selectivity coefficients (α>2.00) for all saccharides tested. The adsorption isotherm followed the Langmuir model. Characterization confirmed successful imprinting, with the imprinted polymer exhibiting a surface area of 69.4m2/g and pore volume of 0.26cm3/g, compared to 8.7m2/g and 0.03cm3/g for the non-imprinted polymer. D-xylose separation was tested using hemicellulosic hydrolysate from sugarcane straw and bagasse. The polymer applied as a sorbent in dispersive solid-phase extraction with the hydrolysate achieved 90.29±1.27% D-xylose adsorption. Desorption in pure water recovered 81.48±1.22% of the adsorbed D-xylose. This method advances separation techniques, offering an efficient solution for sample pre-treatment and expanding the application of MIPs.

Green fabrication of cost-effective and sustainable nanoporous carbons for efficient hydrogen storage and CO2/H2 separation

In this study, sustainable nanoporous carbon materials that are efficient, renewable, cost-effective and adaptable were developed. These microporous feature carbon adsorbents were synthesized utilizing a straightforward and efficient method. Plum stones are residual fruit materials that offer a financially feasible and sustainable carbon source with exceptional porosity and desirable elemental composition. The plum stones underwent carbonization and were subsequently chemically modified with polyaniline nanofibers and then subjected to chemical activation using different activating agents. This yielded sustainable nanoporous carbon with a high degree of porosity, in conjunction with doping with precious high electron density elements such as O, N and S. The sustainable nanoporous carbons that have been developed exhibits exceptional microporosity, with BET-SSA of 1705 m2 g−1 and a pore volume of 0.726 cm3 g−1, besides, the dominance of ultramicropores of 0.6 nm size. This in addition to convenient doping of oxygen, nitrogen and sulfur elements which are crucial for H2 uptake. The developed nanoporous carbon demonstrated highly promising capabilities for storing H2 molecules at cryogenic and ambient temperatures. The sustainable adsorbent achieved hydrogen storage capacities of 4.63 and 0.45 wt% at 77, 296 K, and a pressure of 40 and 80 bar, respectively. This H2 storage capacity at RT is often regarded as one of the highest reported in the literature for nanoporous adsorbents. Moreover, study investigated the separation selectivity of developed adsorbents for CO2/H2 based on uptake ratio at 30 bar and RT. The results demonstrated a significant separation selectivity reaching a value of 382.5 for the CO2/H2, which is regarded as one of the most elevated values documented in the existing literature for nanoporous carbon materials. Thus, the presented sustainable nanoporous materials have shown great promise for hydrogen storage, pre-combustion CO2 capture and H2 purification applications at ambient temperature.

Experimental and theoretical investigation on a viologen-based coordination polymer: Hydrochromism, solvatochromism, temperature dependent luminescence and selective adsorption and separation of cationic dye methylene blue

In recent years, multi-functional smart discoloration materials with multi-stimuli response property have attracted much attention due to their applications in smart windows, sensors, clothing manufacturing, and so on. In this work, a viologen-based multi-functional coordination polymer [H2L1]2[Mn4(L2)4(H2O)4]∙(H2O)4 (1) (H2L1Cl2 = 1,1′-bis(4-carboxy-benzyl)-4,4′-bipyridinium dichloride and H3L2 = (3,5-dicarboxyl-phenyl)-(4-(2′-carboxyl-phenyl)-benzyl)ether) in response to multiple stimuli has been synthesized hydrothermally. Compound 1 displays a 2D→3D interdigitated supramolecular framework, where the L23− anions link the Mn(II) ions to generate a 2D anionic layer, and the viologen cations H2L12+ are filled between the layers as counterions to balance the charge. Compound 1 can change color from light yellow to orange in response to temperatures from 80 to 265 °C and multiple solvents stimuli, and these changes are reversible. The discoloration mechanism has been investigated by thermogravimetric analysis, UV–vis absorption, electron paramagnetic resonance, infrared and powder X-ray diffraction spectra, and density functional theory calculation. Compound 1 with an anionic layer can occur electrostatic attraction with cationic dye molecules. Therefore, it can be used for selective adsorption and separation of cationic dyes methylene blue. Moreover, compound 1 can be used as a non-contact luminescent thermometer.

Selective separation of dyes and tetracycline hydrochloride in polymer‐nucleotide coacervate droplets

AbstractThis paper reports the formation of coacervates by the electrostatic interaction of poly (diallyldimethylammonium chloride) (PDDA) and adenosine triphosphate (ATP) in aqueous solution, examining its formation conditions, stability, and efficiency in separation. The ideal concentration for creating coacervate droplets in pure water, HEPES buffer, and NaCl solution was determined to be 20 mM of PDDA and ATP. Enhancing the stability of coacervates was achieved by incorporating phospholipid vesicles on their surface, presenting a novel strategy for building cell models. Ostwald Ripening was employed to comprehend the growth mechanism of the coacervates, while the Hofmeister Ion Series and Schulze‐Hardy's rule were utilized to elucidate the stability differences in solutions containing NaCl, Na2SO4, and MgCl2. These coacervates were stable at concentrations below 90 mM NaCl, 200 mM Na2SO4, and 30 mM MgCl2, respectively. We also explored the specific separation of dyes and tetracycline hydrochloride (TC) in the coacervates. Separation efficiencies of 92.98% for methylene blue (MB), 94.19% for methyl orange (MO), and 85.94% for TC, were achieved by the coacervates, which can be attributed to the synergistic effects of hydrophobicity, electrostatic forces, and π‐π interactions. The proposed coacervates have great potential in cell mimicry and water treatment.

Enhanced Propylene/Propane Separation via Aniline-Decorated ZIF-8 Membrane: Lattice Rigidity Adjustment and Adsorption Site Introduction.

Metal-organic framework (MOF)-based membranes excel in molecular separation, attracting significant research interest. The crystallographic microstructure and selective adsorption capacity of MOFs closely correlate with their gas separation performance. Here, aniline was added to the ZIF-8 synthesis in varying concentrations. Aniline, encapsulated within ZIF-8 cavities, interacts strongly with the 2-methylimidazole linker, resulting in both a shift in crystallographic phase from I_43 m to Cm in Rietveld refinement of X-ray diffraction (XRD) patterns and the selective adsorption behavior between propylene and propane. Consequently, an aniline decorative ZIF-8 (Anix-ZIF-8) membrane was prepared using a fast current-driven synthesis method, which exhibits good propylene/propane separation selectivity of up to 85. Calculation of the interaction energy between aniline and the various crystallographic phases of ZIF-8 using density functional theory (DFT) further verifies that aniline not only promotes the formation of crystallographic Cm phase, but also enhances the adsorption selectivity of propylene over propane. Aniline modification effectively tunes the crystallographic microstructure of ZIF-8, thereby, improving molecular sieving capabilities.

Multiple Structural and Phase Transformations of MOF and Selective Hydrocarbon Gas Separation in its Amorphous, Glass Phase States

AbstractThe first wide‐view image of multiple structural and phase transformations for MOFs, ranging from crystal state transformations to the extreme limit approaching liquid/glass phase, was presented. The process involves i) an initial crystalline transformation from square‐layer framework [Co2(pybz)2(CH3COO)2] ⋅ DMF (Co2) to a 3‐fold interpenetrated and ordered vacancies contained framework [Co(pybz)2(CH3OH)2] ⋅ 2CH3OH (CoM) due to in situ disassemble‐reassemble, ii) thermal induced departure of a pair of cis‐form coordinated methanol in CoM leads to amorphous framework a‐dCoM, iii) glass transition to super‐cooled liquid scl‐dCoM, iv) obtaining MOF glass g‐dCoM upon quenching the super‐cooled liquid, and v) re‐crystallization of super‐cooled liquid generates 6‐fold interpenetrated dia‐net framework [Co(pybz)2]6n (rec‐dCoM) under further heating. The access to glass from CoM, provides a new self‐perturbation strategy to create MOF glasses without melting. The wider pore size distribution in amorphous/glassy MOFs than crystalline precursor achieved the first time selective hydrocarbon gas separation by breakthrough experiments, which bring efficient separation of 1 : 99 C2H2/C2H4 by either a‐dCoM or g‐dCoM and produce polymer grade C2H4 with purity≥99.5 % after a single adsorption process. Furthermore, the mixture of 50 : 50 C3H6/C3H8 can be separated by a‐dCoM.

Multiple Structural and Phase Transformations of MOF and Selective Hydrocarbon Gas Separation in its Amorphous, Glass Phase States.

The first wide-view image of multiple structural and phase transformations for MOFs, ranging from crystal state transformations to the extreme limit approaching liquid/glass phase, was presented. The process involves i) an initial crystalline transformation from square-layer framework [Co2(pybz)2(CH3COO)2] ⋅ DMF (Co2) to a 3-fold interpenetrated and ordered vacancies contained framework [Co(pybz)2(CH3OH)2] ⋅ 2CH3OH (CoM) due to in situ disassemble-reassemble, ii) thermal induced departure of a pair of cis-form coordinated methanol in CoM leads to amorphous framework a-dCoM, iii) glass transition to super-cooled liquid scl-dCoM, iv) obtaining MOF glass g-dCoM upon quenching the super-cooled liquid, and v) re-crystallization of super-cooled liquid generates 6-fold interpenetrated dia-net framework [Co(pybz)2]6n (rec-dCoM) under further heating. The access to glass from CoM, provides a new self-perturbation strategy to create MOF glasses without melting. The wider pore size distribution in amorphous/glassy MOFs than crystalline precursor achieved the first time selective hydrocarbon gas separation by breakthrough experiments, which bring efficient separation of 1 : 99 C2H2/C2H4 by either a-dCoM or g-dCoM and produce polymer grade C2H4 with purity≥99.5 % after a single adsorption process. Furthermore, the mixture of 50 : 50 C3H6/C3H8 can be separated by a-dCoM.

Comparison of liquid–liquid phase equilibrium behavior of acetonitrile–water system using choline chloride salt and water-based deep eutectic solvent

The liquid–liquid equilibrium (LLE) data for the ternary systems of (acetonitrile (ACN) + water (W) + choline chloride (ChCl)) and (ACN + W + water-based deep eutectic solvent (WDES) consisting of ChCl:W (1:3)) were measured at 298 K. The consistency of tie-lines was verified by the Bachman and Othmer–Tobias correlations. ChCl as an organic salt and its WDES (within the water content range of less than 50 w%) as green extractants represent feasible performances in terms of selectivity and distribution coefficients for separation of water from acetonitrile-water system in comparison to other inorganic salts and hydrophobic DESs. ChCl in the (ACN + W + ChCl) system can separate water from the solution in the form of hydrate ions while WDES in the (ACN + W + WDES) system tends to absorb water by intermolecular forces. The experimental data of the (ACN + W + ChCl) system was correlated using the symmetric electrolyte non-random two liquid (e-NRTL) model while the equilibrium data of the (ACN + W + WDES) system was correlated using NRTL and universal quasi-chemical activity coefficient (UNIQUAC) models. ChCl in the form of salt represents a better separation performance than WDES for water removal from the acetonitrile mixture. Meanwhile, WDES might be considered to be superior compared to ChCl in terms of regeneration energy consumption and operating considerations.

Unveiling the depression role of quercetin in selective flotation separation of chalcopyrite from pyrite at low alkalinity

In flotation, the separation and concentration of copper-iron sulfide ores are usually carried out at high alkalinity to depress pyrite, and plenty of lime could block the flotation pipeline and affect the recovery of precious metals during practical operation. Herein, the current research hotspot to achieve the separation of copper-iron sulfide ores under low alkalinity. This paper presented an eco-friendly reagent, quercetin, for the flotation separation of chalcopyrite and pyrite, and investigated the effect on the flotation performance of the two minerals. The interaction mechanism of quercetin with mineral was demonstrated using zeta potential measurements, atomic force microscopy (AFM), surface adsorption measurements, Fourier-transform infrared spectroscopy (FT-IR), and X-ray Photoelectron Spectroscopy (XPS). The flotation results showed that the depressive effect of quercetin on pyrite was more pronounced in comparison to its impact on chalcopyrite at pH 8.0, and the chalcopyrite recovery reached 90 %, whereas that of pyrite was under 10 %. The surface analysis revealed quercetin chemisorption on the mineral surface through interaction with metal sites. In the presence of quercetin, the quercetin significantly diminished the ability of pyrite to adsorb xanthan but had minor effects on the adsorption of chalcopyrite.

Unveiling gas transport mechanisms in tunable MXene nanochannels: Insights from molecular dynamics simulations

MXene-based membranes have shown tremendous potential in gas separation applications. Here, molecular dynamics (MD) simulations are used to investigate the effects of varying the structural parameters of Ti₃C₂O₂ nanochannels on the permeation and separation performance of H₂, CO₂, N₂, and CH₄ gases. The results demonstrate that the interlayer spacing significantly influences gas permeability, with wider channels generally exhibiting higher permeance. Channel length, however, has a relatively minor impact on permeability, varying by gas species. Potential of mean force (PMF) analysis reveals that CO₂ molecules face a notable energy barrier at the channel entrance and have the strongest interactions with the MXene interface within the channel, potentially leading to blockage. Spatial density analysis further confirms this CO₂ blockage phenomenon, which diminishes as the interlayer spacing increases. In terms of gas separation selectivity, H₂/CH₄ and H₂/CO₂ mixtures exhibit high selectivity, with maximum values of 41.08 and 27.06, respectively. Notably, the H₂/CO₂ system exhibits a positive correlation between permeability and selectivity, breaking the traditional permeability-selectivity trade-off. This anomalous behavior can be attributed to the CO₂ blockage effect. This study provides theoretical guidance for the design and optimization of MXene-based membrane materials in practical applications.

Tailored microporous graphitic carbon adsorbents from the urea-assisted method for efficient selective gas adsorption and separation of CH4/N2 and CH4/H2

Currently, the adsorption and separation of methane (CH4) from CH4/N2 and CH4/H2 have attracted global attention as an essential technique for the utilization of unconventional natural gas and to meet energy demand. This technique completely relies on the adsorbent; the development of the adsorbent can achieve selective CH4 adsorption and separation. In this context, microporous graphitic carbon adsorbents were tailored using hydrothermal and calcination methods. The textural features of adsorbents were precisely tailored using a hydrothermal approach by optimizing the glucose-urea ratio, and they were then activated with the non-corrosive reagent K2CO3, which gives a specific pore structure that aids in performance. Adsorbents’ textural characteristics, such as surface area and porosity, were significantly influenced by the glucose-urea ratio, which plays an essential role in gas adsorption and separation. A series of tailored microporous graphitic carbon adsorbents named 0.5-HTAC, 1-HTAC, 1.5-HTAC, 2-HTAC, 1.5-HTAC-a, 1.5-HTAC-b, and 1.5-HTAC-c. Among them, 1.5-HTAC adsorbent displayed superior CH4 gas adsorption (36.86 cm3/g) and excellent selectivity of CH4/N2 (6.29) at room temperature, owing to its microporosity, good surface area, and morphological effect. Meanwhile, H2 gas adsorption was not detected at room temperature, indicating that the 1.5-HTAC adsorbent is extremely selective for CH4 gas. However, an additional study of H2 uptake performed at 77 K revealed excellent H2 adsorption of about 314.3 cm3/g. Furthermore, the 1.5-HTAC adsorbent exhibited a low heat of CH4 adsorption as well as impressive reversibility, indicating that it can be reused more effectively.

A Study on the Potential for the Application of Peanut Shells as a Reducer in the Process of Metal Recovery from Metallurgical Slags

Copper production technology is a complex process consisting of many stages. The combination of pyrometallurgical and hydrometallurgical stages, on the one hand, complicates production while, on the other hand, allowing for a relatively selective separation of intermediate or waste materials that can be subjected to the process of recovery of useful components. Materials of this type are characterised by a much higher copper content relative to the ore material. On the other hand, due to the oxide form, reduction processes are used in which coke is mainly applied. Reduction of the unfavourable phenomenon of CO2 emissions, in this case, can be performed through the use of bioreducers, which are characterised by an inert carbon footprint since the generation of carbon dioxides is the same as its absorption at the stage of vegetation and growth. In this paper, the topic of determining the feasibility of using selected bioreducers, such as peanut shells, to verify their suitability in the process of reducing copper oxides as well as the impact on the working components of the laboratory reactor in which the process is carried out are discussed. In this case, raw materials with a composition similar to the that of slags produced at the copper production stage in a flash furnace were tested for reduction. The results referring to reducing lead and copper contents above 88% Pb and 98% Cu indicate the great potential of this type of bioreducer. An additional advantage is the relatively wide availability of peanut resources. The effects of the copper reduction time on the degree of decopperisation performed with a constant reducer addition at 1300 °C were studied in this paper. Following 1 h of the process, the copper content in the slag was 0.78 wt%, while the longer process duration resulted in a copper fraction of 0.19 wt%. Considering lead, its content was 0.33 wt% after the reduction process.

Viscoelastic and antimicrobial dental care bioplastic with recyclable life cycle

Medical plastic-appliance-based healthcare services, especially in dentistry, generate tremendous amounts of plastic waste. Given the physiological features of our mouth, it is desirable to substitute dental care plastics with viscoelastic and antimicrobial bioplastics. Herein, we develop a medical-grade and sustainable bioplastic that is viscoelastic enough to align the tooth positions, resists microbial contamination, and exhibits recyclable life cycles. In particular, we devise a molecular template involving entanglement-inducing and antimicrobial groups and prepare a silk fibroin-based dental care bioplastic. The generated compactly entangled structure endows great flexibility, toughness, and viscoelasticity. Therefore, a satisfactory orthodontic outcome is accomplished, as demonstrated by the progressive alignment of male rabbit incisors within the 2.5 mm range. Moreover, the prepared bioplastic exhibits resistance to pathogenic colonization of intraoral microbes such as Streptococcaceae and Veillonellaceae. Because the disentanglement of entangled domains enables selective separation and extraction of the components, the bioplastic can be recycled into a mechanically identical one. The proposed medical-grade and sustainable bioplastic could potentially contribute to a green healthcare future.

Efficient Li+/Mg2+ separation by two-dimensional montmorillonite membrane with stable channel structure through ion exchange and metal–organic coordination strategy

Two-dimensional (2D) nanochannel membranes stacked by nanosheets are promising membrane separation materials. However, intrinsic swelling properties of 2D membrane have emerged as a significant challenge to establish stable nanochannels and achieve high separation performance. Inspired by the natural ion exchange property of montmorillonite (MMT), we constructed a two-dimensional MMT membrane with robust nanochannels by exchanging Fe3+ into interlayer of the membrane, and further achieved efficient separation of Li+/Mg2+ through coordination manipulation of tannic acid (TA) and Fe3+. Swelling was dramatically prevented by strong interlayer interaction between exchanged Fe3+ and nanosheets resulting in a 32-fold increase in anti-swelling properties. Furthermore, experiments and simulations revealed that TA could rapidly chelate with Fe3+ to form a dense hydrophilic functional layer on the membrane interface, which endowed MMT membranes with enhanced mechanical strength, cation transport and recognition, as well as anti-fouling properties. Consequently, the resulting MMT membranes showed the Li+/Mg2+ selectivity as high as 9.98 with a fast Li+ permeation rate (0.108 mol m-2 h-1), which exceeded most of the previously reported membranes. This study proposed a novel strategy to diminish the trade-off effect among stability, ion flux, and selectivity of membranes, and inspired the development of next-generation ion selective separation membranes.

Molecularly imprinted composite membranes with the dual imprinted network for highly selective separation of acteoside

Acteoside (ACT) is the main active ingredient in phenylethanoid glycosides (PhGs) and it has anti-inflammatory, liver-protecting, and memory-enhancing functions. It remained a challenge to develop an imprinted membrane with high permselectivity for separation of ACT from PhGs. In this paper, ACT was used as a template molecule to design dual imprinted molecularly imprinted composite membranes (DIMICMs). The dual imprinted network structure was constructed and played a vital role in DIMICMs. On one hand, ACT imprinted network was formed on the surface of ACT-KH570/PDA/CMK-3@PVDF, and it can recognize and adsorb ACT. On the other hand, the imprinted filler ACT-KH570/PDA/CMK-3 was mixed with PVDF powder to construct the ACT imprinted network in the membrane, and the imprinted network can further recognize and accommodate the ACT. The dual imprinted network acted synergistically for dual recognition of ACT. The result showed that the DIMICMs had the high permselectivity (β = 14.61), selectivity (α = 4.64) and rebinding capacity (105.58 mg/g). The designed approach of DIMICMs with a dual imprintednetwork provided a strategy for the separation of natural products.

Zwitterionic Nanochannels in Covalent Organic Framework Membranes for Improved Flux and Antifouling Property.

Zwitterionic membranes demonstrate excellent antifouling property in water purification. The covalent organic frameworks (COFs), due to the ordered channels and abundant organic functional groups, have distinct superiority in constructing zwitterionic surfaces.Here, the zwitterionic COF membrane is prepared with precise framework structures and uniform charge distribution. The negatively charged 4,4'-diaminobiphenyl-2,2'-sisulphonic acid sodium (SA) and positively charged ethidium bromide (EB) fragments are used to react with 1,3,5-triformylphloroglucinol (TP) at the gas-liquid interface to prepare zwitterionic COF membrane. The complementary charged fragments in the inter-layer and inner-layer facilitate the formation of continuous and tight hydration layer on the membrane surface and pore walls to resist the adsorption of pollutants. The zwitterionic COF membrane effectively resists both negatively charged bovine serum albumin and positively charged lysozyme pollutants with flux recovery ratio (FRR) of 97% and 85%, respectively. Furthermore, the regular nano-channels and balanced interactions between water and surface/pore walls of the zwitterionic membrane result in outstanding permeability of up to 146 L m-2 h-1 bar-1 and excellent dye/salt separation selectivity. The water permeation and antifouling mechanism of membranes are elucidated by experimental and molecular dynamics calculation. Zwitterionic COF membranes can find promising applications in preparing high-performance antifouling membranes.

Boronate affinity metal–organic frameworks molecularly imprinted membranes with hierarchical porous channels for the selective separation of naringin

Naringin (NRG), known as an important natural flavoniod compounds, exhibits excellent phamaceutical value and clinical application prospect. However, the main obstacle to the isolation and purification of NRG is the low concentration and complexity of the extraction system. Herein, a new kind of hierarchical porous metal–organic frameworks (MOFs) based molecularly imprinted membranes (PBMMA-MIMs) for the specific separation of NRG. The prepared PBMMA-MIMs showed the fast adsorption kinetics (within 120 min). Moreover, the abundant boronic acid imprinted recognition sits and hydrophilic hierarchical porous MOFs improved the adsorption capacity (the maximum adsorption amounts 57.39 μmol/g) and exhibited selective NRG adsorption (imprinting factor 2.31) with efficiency over 91.69 % after seven adsorption–desorption cycles. In addition, the coarse NRG could be effectively extracted to a promising purity of 93.13 % via PBMMA-MIMs. This study provides new insights into the design molecularly imprinted membranes via environmentally friendly synthesis route for the preparation for enriching high-value flavoniods, achieving efficient purification rate of agricultural wastes for pollution control, and promoting the sustainable reuse in complex agricultural wastewater.

The mechanism of selective separation of stibnite and arsenopyrite by Cu2+ coordination assembly KBX collector

The similar physicochemical properties of stibnite and arsenopyrite resulted in the difficult separation by traditional collectors in flotation. Hence, this study utilized Cu2+ and potassium butyl xanthate (KBX) coordinate assembly to form a novel Cu-KBX complex collector, investigating its properties, conformation, and its role in flotation separation of stibnite and arsenopyrite, as well as its diverse adsorption behavior on mineral surfaces. The stable Cu-KBX complex solution was formed when the molar ratio of Cu2+ to KBX was 1:2, exhibiting a network-like structure at that time. The micro-flotation results showed that at pH 5, the grade of Sb in the concentrate was as high as 61.08 %, with As content at only 4.65 %, enabling effective separation of stibnite and arsenopyrite. Furthermore, the Cu-KBX complex exhibited a reticulated structure at the stibnite surface, while it adhered in a granular fashion on the arsenopyrite surface. FTIR analysis confirmed stronger chemisorption of Cu-KBX onto stibnite compared to arsenopyrite. XPS results indicated that Cu-S was the main collecting component. However, a weak Fe(II)-S substance was found on the arsenopyrite interface, likely due to Fe3+ oxidizing in the slurry with the Cu-KBX complex. Therefore, this disruption of the Cu-KBX complex structure by Fe3+ in arsenopyrite sharply reduced its adsorption on arsenopyrite, enhancing the selective separation of stibnite and arsenopyrite.