Liquid Separation Research Articles

Evaluation of a simultaneous approach to concentrate and preserve bioactive compounds with distinct polarities by employing supramolecular solvents (SUPRAS)

Supramolecular solvents (SUPRAS) have attracted attention as eco-friendly and highly effective solvents that can be tailored to solubilize compounds with distinct polarities. This study investigated the SUPRAS/equilibrium solution systems’ (SUPRAS-EqS) capacity to concentrate and preserve bioactive compounds through simultaneous solvent production and a liquid–liquid separation method. For this, β-carotene, quercetin, and curcumin were evaluated as molecular probes. SUPRAS-EqS systems were produced with octanoic acid (5 %, v/v), ethanol (20–––35 %, v/v), and acidified water (75–––60 %, v/v) and characterized concerning SUPRAS phase formation and their composition. Moreover, the SUPRAS phase’s ability to preserve these compounds during thermal exposure was evaluated at 313.15 K, 323.15 K, and 333.15 K and compared with an ethanolic medium. The outcomes demonstrated the formation of spherical supramolecular aggregates (10 to 20 μm), where the size of coacervates increased proportionally with the ethanol concentration. Concerning the separation efficiency provided by the SUPRAS phase, all compounds exhibited values superior to 83 %, and the systems produced with 22.5 % ethanol for quercetin and curcumin, and 27.5 % ethanol for β-carotene, presented the highest partition coefficient values. The SUPRAS phase promoted a more suitable environment to preserve the bioactive compounds than ethanol, and quercetin exhibited the highest half-life time values. Curcumin displayed the strongest activation energy in both the SUPRAS phase (48.88 kJ/mol) and the ethanol media (54.50 kJ/mol), indicating its high temperature dependence compared to the other compounds. These findings highlight the SUPRAS phase capacity to concentrate and stabilize bioactive compounds individually with different polarities.

Re-entrant phase transitions in Laponite/Gum Arabic nanocomposites

A re-entrant gel transition is observed in a discotic clay, Laponite (Lap) aqueous suspensions with the addition of a complex polysaccharide, Gum Arabic (GA). For fixed concentrations of Lap (1–3 % w/v) and at low GA concentrations (CGA < 10 % w/v), the composites exhibit gel behaviour, while the suspensions undergo liquid phase separation for intermediate GA concentrations (10 % w/v < CGA < 20 % w/v). Gel behaviour is again observed in the samples at even higher GA concentrations (CGA > 30 % w/v). Here, we identify a thermodynamic phase transition in Lap/GA mixtures that is caused by a variation in GA content. The viscoelastic characteristics, phase transitions, and gelation kinetics of the Lap/GA mixtures have been studied by employing rheology, small-angle X-ray scattering, and optical investigations. Reduction of the negative values of zeta-potential and growth of the composite system's hydrodynamic size indicated the presence of interactions in Lap/GA mixtures. The phase diagram enables the apparent interactions and phase transitions between the nanoplatelets and the complex polysaccharides. Thus, our study provides new perspectives on a nanocomposite's tuneable rheological and structural features.

Effects of water salinity and temperature on oil-in-water emulsions stabilized by a nonionic surfactant

The goal of this work is to understand the effect of water salinity of three salts- NaCl, CaCl2, and MgCl2- on oil-in-water (O/W) emulsions stabilized by nonionic surfactants such as Tergitol 15-S-7 (T15S7). The study investigates not only the impacts of mixing speed, water salinity, and temperature but also the combined effects of salt and temperature on emulsion stability. All emulsions were created using ExxsolTM D110 and distilled water, with a surfactant concentration of 0.050 % wt. in the water phase. Two oil fractions (10 % and 25 % by volume) were studied, and oil and water separation interfaces were measured using a state-of-the-art apparatus, which can record and scan videos of free liquid separation. According to the experimental findings, at concentrations higher than the surfactant’s Critical Micelle Concentration (CMC), neither of the divalent salts affects the surface tension of the aqueous solution. Divalent ions, on the other hand, were found to decrease the surfactant’s effectiveness at concentrations lower than the CMC. Conversely, monovalent ions had no effect at low concentrations but further reduced the surface tension at large concentrations. All salts, however, had no effect on the volume of the emulsion for more than 4 h at 25 °C, however at 70 °C, 100 % separation happens in a matter of seconds. Decrease in mixing speed from 2500 RPM to 800 RPM caused the emulsion volume to decrease by at least 72 %.

Kinetics and dynamics of Gas-liquid separation and bubble generation in surfactant solutions: Role of bulk/interfacial properties and hydrodynamic conditions

Understanding the kinetics and dynamics of gas–liquid separation and bubble generation in surfactant solutions is important for many industrial applications. To explore the potential mechanisms affecting the physical properties (expansion ratio, bubble size, and foam stability) of foams and bubbles, the surface tension of the solution, including the equilibrium and dynamic properties, was investigated. Then, the morphology of the surfactant aggregates was explored by cryo-transmission electron microscopy (cryo-TEM). Based on these experimental results, the effects of various physical and chemical factors (including the relative concentration of surfactant, dynamic surface tension, surface coverage, surface elasticity, surface mobility, aggregate morphology, etc.) on the expansion ratio and bubble size were analysed to identify which “universal” parameters can explain the phenomenon for all aqueous solutions in the gas–liquid separation process. Research has shown that the morphology of aggregates in a solution largely determines the surface properties of the solution at 1.5 ms (surface tension, surface coverage, surface elasticity, and so on). These surface properties significantly affect the expansion ratio. However, no good correlation was found between bubble size and these surface properties because surfactant vesicles can directly affect bubble size. In addition, the liquid flow rate and gas–liquid ratio have a significant impact on the expansion ratio and bubble size. Ultimately, we found that the foam stability, bubble size, and expansion ration can be described by a simple linear relationship. Our research provides new opinions for further understanding the effects of bulk/interfacial properties and hydrodynamic conditions on the physical properties of bubbles in the gas–liquid separation process.

Liquid-liquid equilibrium of binary ethanol–polyisobutene and ternary ethanol–water–polyisobutene systems under low- and high-pressure conditions: An assessment using the PC-SAFT equation of state

Sugarcane bioethanol in either anhydrous or hydrous forms stands out as an economically viable bioproduct that can be used as a fuel or feedstock in various innovative applications, reducing human-generated greenhouse gas emissions. Low-molar-mass polyisobutene (PiB) is used as a lubricant in sugarcane-processing plants and is a possible contaminant of sugarcane bioethanol. Understanding the liquid–liquid equilibrium (LLE) of ethanol–PiB binary systems and ethanol–water–PiB ternary systems is essential to avoid undesired phase separation at high-pressure engine conditions and other potential innovative applications. However, the experimental investigation of these systems is significantly hampered by very low polymer solubilities in aqueous ethanol. The LLE of ethanol-PiB and ethanol–water–PiB mixtures was qualitatively investigated using the PC-SAFT equation of state through the development and implementation of extrapolation strategies allowing to estimate ethanol–PiB and water–PiB binary parameters using experimental data obtained for other systems containing lighter alkanes. Phase diagrams were calculated considering temperatures ranging from 298.15 K to 350 K and pressures ranging from 1 bar to 200 bar. It was shown that lower pressures, higher temperatures, lower PiB molar masses, and lower water contents increase the polymer solubility in the solvents. Thus, the risk of liquid–liquid separation can be mitigated by correctly managing such operational parameters. The obtained phase diagrams may present significant quantitative deviations from reality because of the model’s sensitivity to the estimated binary parameters. Thus, they should be interpreted as general qualitative guidelines to avoid and manage undesired phase separation in industrial processes and engines rather than phase equilibrium predictions.

Application of Ionic Liquids in Environmental and Food Fields

Abstract: As a new type of green solvent, ionic liquids have made rapid progress in the fields of organic synthesis, separation, and electrochemistry due to their unique physical and chemical properties. At the same time, the new fluorescence characteristics and good separation and adsorption functions of ionic liquids have gradually developed in the field of environment and food, showing a good application prospect. Based on the work of our research group and the progress and development of research technology, this article reviews the research results of ionic liquids in environmental monitoring and food detection and extraction in recent years. In the environmental field, ionic liquids have the ability of detection and remediation and they show the advantages of fast, efficient, green and recyclable in the detection of environmental pollutants. In the field of food, ionic liquids provide a new idea for the detection and extraction technology of food components. While ensuring green, safe and pollution-free, they show superior selectivity, repeatability and stability, and simplify the operation steps and costs to a certain extent, showing the capture vitality with life characteristics. As a potential smart material, the mechanism of ionic liquids as fluorescent probes and separation extractants was discussed. Finally, the future development and research directions of ionic liquids are prospected, and it is expected to realize the intelligentization of ionic liquid materials and the general integration of development.

Advancements in Biopolymer‐Derived Graft Copolymers: A Comprehensive Review on Their Application in Sustainable Wastewater Treatment

ABSTRACTRising concerns over water pollution and the depletion of non‐renewable resources have propelled the exploration of eco‐friendly and sustainable wastewater treatment alternatives. Biopolymer‐derived graft copolymers emerge as a promising solution, offering biodegradability, cost‐effectiveness, versatility, and enhanced functionality. This review provides a comprehensive overview of the latest developments in utilizing these copolymers as eco‐friendly flocculants for wastewater treatment. It covers synthesis methods for functionalized biopolymer‐based flocculants, diverse flocculation mechanisms, and their efficacy in solid–liquid separation. The article explores applications for removing pollutants, emphasizing biodegradability, cost‐effectiveness, and versatility. Special attention is given to the environmental impact, critically analyzing how these copolymers contribute to sustainable water treatment practices. The review also discusses potential future prospects and advancements in addressing global water pollution challenges using biopolymer‐derived graft copolymers.

Sterol–lipids enable large-scale, liquid–liquid phase separation in bilayer membranes of only two components

Despite longstanding excitement and progress toward understanding liquid-liquid phase separation in natural and artificial membranes, fundamental questions have persisted about which molecules are required for this phenomenon. Except in extraordinary circumstances, the smallest number of components that has produced large-scale, liquid-liquid phase separation in bilayers has stubbornly remained at three: a sterol, a phospholipid with ordered chains, and a phospholipid with disordered chains. This requirement of three components is puzzling because only two components are required for liquid-liquid phase separation in lipid monolayers, which resemble half of a bilayer. Inspired by reports that sterols interact closely with lipids with ordered chains, we tested whether phase separation would occur in bilayers in which a sterol and lipid were replaced by a single, joined sterol-lipid. By evaluating a panel of sterol-lipids, some of which are present in bacteria, we found a minimal bilayer of only two components (PChemsPC and diPhyPC) that robustly demixes into micron-scale, liquid phases. It suggests an additional role for sterol-lipids in nature, and it reveals a membrane in which tie-lines (and, therefore, the lipid composition of each phase) are straightforward to determine and will be consistent across multiple laboratories.

Computational fluid dynamics modeling of gas bubble separation efficiency in downhole separators and vertical / inclined annulus: An experimental validation and analysis

This study presents a comprehensive investigation into gas bubble separation efficiency in a vertical downhole separator using computational fluid dynamics (CFD) modeling, which is validated with experimental data. The research aims to provide detailed insights into the separation mechanisms and the factors affecting them, such as liquid velocity, gas bubble sizes, and positions. Using an Euler-Lagrange multiphase model, the behavior of individual gas bubbles within the liquid-gas mixture was simulated. The results demonstrate that separation efficiency decreases as the liquid flow rate increases. This reduction in efficiency occurs because the increased liquid flow rate drags more bubbles within the stream, making it harder for them to separate. The separation process is primarily driven by the buoyancy force acting on the bubbles and the velocity profile of the liquid flow. Smaller bubbles, which tend to be near the casing wall, separate more efficiently, while larger bubbles are predominantly located between the second and third quarters of the annulus space. The "quarters" refer to radial divisions from the casing wall to the tubing wall, with the first quarter closest to the casing wall and the fourth quarter closest to the tubing wall. The study introduces a nonlinear regression model based on the numerical results to predict liquid slug separation efficiency. This model, validated against experimental data, accurately predicts separation efficiency and offers a robust methodology for estimating the efficiency of gravity-driven gas-liquid separators. This methodology is crucial for refining separator design and improving the operational efficiency of downhole separation systems, which are vital for enhancing the performance of pumping systems in oil and gas wells. The contributions of this study include a deeper understanding of the downhole separation process, the development of a simplified model for assessing bubble separation efficiency, and the potential application of the proposed methodology to different gas-liquid separator designs and inclination angles, thereby informing the design and operation of downhole separation systems.

A simple and efficient approach for pore structure optimization and hydrophilic modification of PTFE nanofiber membrane

Polytetrafluoroethylene (PTFE) membranes have great potential for treating wastewater in harsh environment due to their excellent stability. However, difficulties in the pore structure optimization and functional modification of biaxial stretched PTFE membrane have limited its further applications in liquid separation. Herein, we presented a simple and efficient approach for the preparation and hydrophilic modification of electrospun PTFE nanofiber membranes. This method involved optimizing the pore structure of PTFE nanofiber membranes through adjusting the mass ratio of the spinning carrier polyethylene oxide (PEO) and PTFE, followed by introducing the acetalized polyvinyl alcohol (PVA) on the membrane’s pore surface to improve the hydrophilicity. The average pore size changed from 288.5 to 161.3 nm, while the water contact angle reduced from 135.7° to 50.9°, which not only increased the water permeate flux from 68.56 to 1056.16 L·m−2·h−1, but also achieved high rejection rates of 99.3 % and 97.3 % for carbon (1 μm) and SiO2 (100 nm) particles respectively. Meanwhile, the obtained PTFE nanofiber membrane also exhibited excellent hydrophilic stability after long term exposure to harsh environments (pH=2 HCl, pH=12 NaOH, 1000 ppm NaClO) and 100 friction cycles (5 g weights on 1000 mesh sandpaper). This approach of preparing hydrophilic PTFE nanofiber membranes showed significant potential for practical applications in wastewater treatment.

Novel 1,3-Dimethylimidazolium Dimethyl Phosphate Ionic Liquid for Efficient Separation of the 1,3,5-Trioxane/Water Azeotropic System by Extractive Distillation: Molecular Insights and Process Enhancement

Novel 1,3-Dimethylimidazolium Dimethyl Phosphate Ionic Liquid for Efficient Separation of the 1,3,5-Trioxane/Water Azeotropic System by Extractive Distillation: Molecular Insights and Process Enhancement

Highly efficient direct air capture using solid–liquid phase separation in aqueous diamine solution as sorbent

Abstract To reduce climate change, absorbing CO2 directly from the air (DAC) with high-efficient CO2 absorption, low-cost, and environmentally friendly system has been attracted much attention for several decades. In this work, a series of aqueous diamine solutions was examined for 400 ppm CO2 absorption at ambient temperature. The absorbents exhibited CO2 absorption with molar ratio of 1 molCO2/molamine, and aqueous isophorone diamine (IPDA) in particular showed &amp;gt;99% CO2 removal even under a 500 mL min−1 flow of 400 ppm CO2–N2 with the contact rate of 13,761.5 h−1 between CO2 and IPDA aqueous solution and the CO2 absorption rate of 4.46 mmol/L min. A precipitate of carbamic acid of IPDA was formed by reaction with CO2, and the CO2 removal efficiency was enhanced by increasing the solution viscosity by the formation of this precipitate. The CO2 was absorbed in aqueous IPDA solution as carbamic acid of IPDA and bicarbonate/carbonate species, and the absorbed CO2 could desorb by heating under O2-containing gas flow, which indicates our system is applicable to the CO2 condensation for a plant growth. This work provides fundamental information to establishing a solid–liquid phase change system with a high-efficient and environmentally friendly DAC system using aqueous solvent.

Occurrence, distribution and fate of iodine during phosphate ore beneficiation process

Numerous beneficiation techniques, such as washing, grinding, flotation, digesting, and calcination, are used to concentrate the minerals found in phosphate rocks, which include apatite, carbonatites, and silicates. Significant iodine levels are often found in phosphate ore minerals, which have a distinctive geochemical occurrence. However, the exact occurrence and distribution of iodine in these minerals are not yet thoroughly understood. A study was carried out to investigate the iodine's distribution, occurrence modes (phases), and release rate in Moroccan phosphate as it undergoes the beneficiation process. The samples underwent a multi-analytical approach combining mineralogical and chemical characterization using ICP-MS, ICP-OES, XRD, elements titration, and Pearson correlation analysis for interelement relationships. Calcination, digestion, and Heavy liquid separation is used to study the fate of iodine. The analysis indicates that iodine is primarily found in fluorapatite, with local concentrations ranging from 35 to 130 ppm. The most enriched grains/zones are associated with fluorapatite, enriched in P2O5, F-. in addition, iodine is positively correlated with its main components, including P2O5, F-, SO3, Na2O, CaO, and REEs. The flotation and heavy liquid separation process used for calcite and silicate removal is acting as an iodine and P2O5 concentrator, given that 99 % of iodine occurs in the apatite phase. However, it has been demonstrated that iodine can be released during the digestion of phosphate rock. Where the initial iodine content is distributed among phosphoric acid, PG, and the gaseous phase, constituting 35 %, 25 %, and 40 %, respectively. Furthermore, the calcination of phosphate rock between 800–1000 °C shows that total iodine is released with gases in I2 form, leading to an increase in the concentration of iodine in the surrounding area. In this regard, an integrated pyrometallurgical process has been proposed for the valorization of iodine as silver iodide. This process involves trapping gaseous iodine in an alkaline solution, followed by precipitation, thereby contributing to the overarching objectives of the circular economy and environmental protection.

Cyclone-coalescence separation technology for enhanced droplet removal in natural gas purification process

Natural gas is increasingly recognized as a clean energy source due to its high quality, low pollution levels, and abundant availability. However, certain gas fields contain complex components that require purification for efficient transportation and utilization. Addressing these issues involves efficient gas–liquid separation technology. Existing gas–liquid separation units face challenges such as efficiency, liquid entrainment, energy consumption, and the need for consumable replacement. This study focuses on a novel cyclone-coalescence separator that combines centrifugal and coalescence principles. Implemented in a high-acid natural gas purification plant in China, the cyclone-coalescence separator demonstrated efficiency primarily influenced by gas velocity and diameter. Optimal performance was observed with a 75 mm diameter reactor at velocities of 8–12 m s−1, achieving a peak efficiency of 96%. The hydrophilic glass fiber with a monofilament structure can coalesce droplets effectively. In practical industrial use, under operational conditions, the hydrocyclone's liquid discharge rate is 89.6 kg·h−1 with an inlet concentration of 382.7 g·m3. Over a 400-h cycle, the cyclone-coalescence separator demonstrated superior separation performance with an average liquid discharge volume of 9.09 mg·kg−1, compared to 4.93 mg·kg−1 for the precision filter. This successful industrial implementation presents a promising approach to natural gas purification.

The insight into behavior and mechanism of chitosan-embedded hydroxyapatite gel spheres used for efficient solidification of uranium in wastewater

In this work, hydroxyapatite (HAP), an environmentally friendly material was prepared with Phosphogypsum (PG) as calcium source, and uranium immobilization gel spheres were prepared by chitosan (CS) embedding, which would reduce HAP agglomeration while providing an abundance of uranium-loving groups, realizing “treating waste for waste”. The optimum pH for U(VI) removal was determined to be 4, the optimum dosage was 0.2 g/L, and qmax = 350.88 mg/g through batch experiments. When C0 = 10 mg/L, it was found that the removal rate of U(VI) by HAP-CS could be up to 99.92 %, and the residual uranium concentration was 0.008 mg/L, which meets the national emission standard. The removal rate of uranium can reach 95.92 % by applying it to high concentration uranium ore wastewater. CS was found to have good biocompatibility with HAP by SEM, FTIR, XRD, and XPS characterization. Meanwhile, we found that Ca, –OH, and P-O play a dominant role in the uranium removal process, and the main mechanism of uranium removal by Hydroxyapatite-Chitosan gel spheres (HAP-CS) is surface complexation, ion exchange, and dissolution–precipitation binding. The HAP-CS has high uranium removal efficiency, simple solid–liquid separation, and good biocompatibility, and can be used to treat actual uranium-containing wastewater.

Review on spray characteristics of liquid–liquid injectors in liquid rocket engines

Impinging-jet injectors, liquid–liquid coaxial swirl injectors, and liquid–liquid pintle injectors are representative liquid–liquid injectors in liquid rocket engines (LRE). For these liquid–liquid injectors, the atomization processes all involve the liquid impingement, including jet–jet, sheet–sheet, and jets/sheet–sheet impingement, respectively. After impingement, a liquid sheet forms and fragments. Based on these similarities, reviewing published literature on the spray characteristics of these three liquid–liquid injectors in LRE is necessary and will facilitate the investigation of spray characteristics of liquid–liquid pintle injectors to meet the progress of variable-thrust LRE. This review covers the following aspects of these injectors: basic spray morphology, liquid sheet characteristics and disintegration mechanisms, and atomization characteristics. For impinging-jet injectors, rim instability and impact wave play crucial roles in spray morphology and disintegration. Jet Weber number is of great importance for liquid sheet breakup length and mean droplet diameter. In the case of liquid–liquid coaxial swirl injectors, the overall spray morphology is similar to that of pressure swirl injectors, but it may feature two separate liquid sheets. The recess length strongly influences spray morphology, spray angle, breakup length, and Sauter mean diameter. Liquid–liquid pintle injectors can be simplified to injection element, in which the spray morphology resembles a cloak-like shape. In a complete pintle injector, the spray forms a conical liquid sheet. Momentum ratio proves to be the most significant parameter for predicting spray angle. Although the review indicates substantial progress has been made in understanding spray characteristics of liquid–liquid injectors, there remain several shortcomings that require further research, particularly for pintle injectors, which can be learned from the other two injectors.

Preparation of imprinted cryogels of cellulose cross-linked ionic liquids for selective separation of Gd(III) from rare earth leachate

The development of high technology has elevated industry’s dependence on rare earth resources. The hydrometallurgical process is widely used for the separation of rare earth elements (REEs) from rare earth ores, producing acidic leachate with trace amounts of REEs. Recovery of REEs from rare earth leachate not only mitigates the negative impact of leachate on the environment, but also contributes to the realization of sustainable resource utilization. In this study, two novel imprinted cryogel adsorbents, methyltrioctylammonium chloride-derivative carboxymethylated cellulose nanocrystal imprinted cryogel (LR-ICMC) and ethylmethylimidazolium bromide-derivative carboxymethylated cellulose nanocrystal imprinted cryogel (LM-ICMC), were constructed by using carboxymethylated modified cellulose nanocrystals as a backbone structure, and successfully branched ionic liquids (ILs) methyltrioctylammonium chloride-derivative and ethylmethylimidazolium bromide-derivative, respectively, for the separation of gadolinium ions (Gd(III)) from rare earth leachate. Firstly, SEM and TEM results showed that the incorporation of ILs retained part of the pore structure of carboxymethylated cellulose nanocrystals (CMCNCs). BET and TG results illustrated that the incorporation of ILs effectively increased the specific surface area and thermal stability of LR-ICMC and LM-ICMC. FT-IR and XPS results showed that LR-ICMC and LM-ICMC could adsorb Gd(III) by electrostatic and chelating effects. Secondly, adsorption isotherm experiments demonstrated the adsorption capacities of 66.880 mg/g and 75.895 mg/g for LR-ICMC and LM-ICMC, respectively; adsorption kinetic experiments demonstrated the ability of LR-ICMC and LM-ICMC to rapidly adsorb 85.152 % and 87.989 % of the maximum adsorption capacity, respectively, within the initial first 40 min. Finally, cycling experiments demonstrated the advantages of LR-ICMC and LM-ICMC in reuse, maintaining 89.245 % and 90.734 % of the original performance after five adsorption–desorption cycles, respectively. Based on these results, LR-ICMC and LM-ICMC were demonstrated to be highly efficient and reusable adsorbents for selective recovery of Gd(III) from rare earth leachate. This study deepens the application of ILs in solid-phase adsorbents and highlights the great potential of LR-ICMC and LM-ICMC in the field of REEs recovery.

Fabrication of metal‐organic frameworks macro-structures for adsorption applications in water treatment: A review

Metal-organic frameworks (MOFs) are emerging porous organic–inorganic hybrid materials composed of metal centers/clusters and various organic ligands, which are widely used in water and wastewater treatment applications due to their large specific surface area, high porosity, tunable chemical properties and abundant active sites. However, pure MOFs powders have limitations such as poor recovery, blocked pipelines and secondary contamination in practical water treatment processes. Enabling the magnetization of MOFs or immobilizing MOFs as macroscopic MOFs materials offers new opportunities to improve solid–liquid separation performances of powdered MOFs. Besides, macroscopic MOFs materials with outstanding adsorption performance and mechanical properties by the combining of 3D particles and 2D nanosheets MOFs with other substrates are widely used for water treatment. This paper provides a comprehensive review of recent advancements in MOFs macro-structures. We firstly summarized the synthesis strategies of magnetic MOFs composites and various MOFs macro-structures such as hydrogels/aerogels, membranes, beads/spheres, others composites, etc. which can be constructed by various methods, including in-situ growth, solvothermal method, direct mixing, self-assembly, layer-by-layer growth, etc. Innovative preparation strategies to improve the mechanical properties of MOFs macro-structures were highlighted. Next the article discusses its application for adsorptive removal of various pollutants (i.e., dyes, heavy metal ions, oils and organic pollutants) from water. Finally, the challenges of macroscopic MOFs materials and their practical applications are presented, while future research directions to overcome these existing limitations are also pointed out.

Preparation and regulation of high-strength and high-permeability porous ceramic/PDMS composite membranes for gas-liquid separation

Methane detection is crucial in identifying combustible ice within the energy sector. The gas–liquid separation membrane, a key component of methane sensors, plays a critical role in effectively separating methane and water. It significantly enhances the efficiency and stability of detecting methane concentration in situ. However, the related permeability and mechanical property present conflicting requirements in order to achieve optimal membrane performance. This work proposes an investigation into the mass transfer performance of a high-strength composite membrane, utilizing PDMS as the functional layer and porous ceramics as the supporting layer. By adjusting the pore distribution of the porous ceramics, particularly through the use of spherical graphite as a porogen, the study examines the impact of spherical graphite (SG) on the support layer’s morphology and its ability to regulate pore structure. Results indicate that incorporating spherical graphite with a porogen content of 10 wt% and a particle size of 25 μm enhances connections between ceramic grains, resulting in a flexural strength of 56.36 MPa and a permeability coefficient of 1861.57 barrer. This configuration demonstrates good waterproof and breathable performance. Overall, this research presents a novel approach for fabricating methane-water separation membranes, offering valuable insights for underwater methane detection efforts.

Efficient water disinfection against antibiotic-resistant bacteria by visible-light heterogeneous photo-Fenton-like process with atomically dispersed Cu on graphitic carbon nitride as the catalyst

Waterborne microbial contamination poses significant environmental and health risks. Photocatalytic heterogeneous Fenton and Fenton-like processes can offer efficient pathogen removal, with benefits in recycling, solid–liquid separation, and byproduct avoidance. However, their low reaction efficiency and slow kinetics for low-valence metal regeneration are limitations. This study addresses these challenges by incorporating atomically dispersed Cu onto graphitic carbon nitride (g-CN) as a single-atom catalyst (SAC). The Cu atoms are stabilized by pyridinic N atoms through coordination, forming Cu-N4 catalytic sites that enhance photogenerated charge carrier transfer. This leads to a more efficient synergistic photocatalytic-Fenton-like reaction, generating more hydroxyl radicals and achieving effective water disinfection. Results show a 7-log bacterial inactivation of antibiotic-resistant Acinetobacter baumannii within 8 min, surpassing prior photocatalytic-Fenton-like disinfection systems. Density functional theory calculations confirm improved hydrogen peroxide adsorption, electron transport, and electron-hole separation in the Cu-N4 structure. The catalyst’s durability and stability were demonstrated through extensive cycling experiments, ion interference tests, and disinfection trials in various water matrices. Additionally, the Cu-SAC@CN catalyst, loaded onto a polytetrafluoroethylene membrane, achieved a 99% bacterial eradication rate within 20 min. This study provides valuable insights into the potential applications of heterogeneous photocatalytic-Fenton-like systems for efficient eradication of waterborne bacteria.