High Separation Capacity Research Articles

High adsorption separation capacity magnetic MOF-based substrate Fe3O4@ZIF-67@Ag for sensitive and recyclable SERS detection of malachite green in aquaculture

Surface-enhanced Raman scattering (SERS) has been employed for rapid analysis of MG residues. However, the limited affinity of organic analytes for the noble metal nanoparticles restricts its application in detecting trace MG residues. This study developed a recyclable magnetic MOF-based SERS substrate Fe3O4@ZIF-67@Ag. It was observed that compared to Ag nanoparticles, MG has a greater propensity to spontaneously adsorb onto ZIF-67, which has a high specific surface area. The substrate exhibited an ultra-high adsorption capacity for MG (804 mg·g−1 at 20 °C). A synergistic effect arose from the electromagnetic enhancement of Ag nanoparticles and the chemical enhancement of ZIF-67, leading to an increased density of “hot spots” at their interface. The substrate demonstrated an enhancement factor (EF) of approximately 7.1 × 105. It exhibited excellent sensitivity, uniformity, and stability in detecting MG residues in fish pond water and tilapia. Under the role of the substrate, the LOD was 8.7 × 10−10 M for fish pond water and 0.17 ng·g−1 for tilapia. Satisfactory recoveries ranged from 84.0 to 96.0 % and 80.0 to 106.0 % respectively. Additionally, it can be conveniently collected from the complex matrix using a magnet and regenerated through a simple and economical ethanol-washing method, thus significantly reducing the cost of testing.

Facile one-pot in-situ hydrothermal preparation of 0D/2D Mn3O4/CdS heterojunctions for improved photocatalytic H2 production and degradation of methylene blue

Developing heterojunction photocatalysts is a critical method to augment the photocatalytic activity of single semiconductors. However, the instability of their heterostructure poses a significant challenge. Herein, a unique 0D/2D Mn3O4/CdS p-n photocatalyst has been prepared by a simple one-pot in-situ hydrothermal approach for H2 production and methylene blue (MB) degradation. The optimized MC-0.18 (18 at% Mn) nanocomposite showed remarkable photocatalytic properties, producing a significantly higher H2 generation rate of 1291 μmol·g−1·h−1, which was 13.7 and 9.2 times higher than that of pristine CdS and ex-situ synthesized MC-0.18-ex photocatalysts, respectively. MC-0.18 displayed the highest reaction rate at 0.0435 min−1 for MB degradation, which was approximately 2.6 and 6.3 times higher than CdS and Mn3O4, respectively. Active species capture experiments and ESR identified •OH and •O2− as the main substances involved in MB degradation. Importantly, MC-0.18 demonstrated excellent stability and reusability in photocatalytic H2 production and MB degradation cycle tests. The formation of unique p-n heterostructures results in enhanced photoactivity due to the matched band alignment between ultrafine Mn3O4 nanoparticles and CdS nanosheets, leading to a high charge separation capacity. This study offers a facile route to design p-n heterojunctions that have remarkable charge transfer abilities to promote H2 production and degrade organic dyes.

Ultralight, shapeable, and superhydrophobic polyacrylonitrile/polybenzoxazine aerogel for high oil-water separation capacity

Environmental and human health are significantly threatened by oily wastewater emission and oil spills. Polymeric porous aerogels are ideal materials to absorb oils or organic solvents selectively, thereby mitigating environmental pollution and protecting human health. In this study, a shapeable, super-hydrophobic, polyacrylonitrile fiber/polybenzoxazine (PAN/PBOZ) aerogel with high oil-water separation ability were successful designed. The preparation process of PAN/PBOZ aerogel is as follows: Firstly, PAN micro-nanofibers were prepared by electrospinning, and then benzoxazine was uniformly dispersed into PAN fibers. After freeze-drying and thermal curing, the aerogel was obtained. For comparative analysis, a pure polyacrylonitrile (PAN) fiber aerogel is also presented. The resulting PAN/PBOZ aerogel exhibits ultralight (0.017 g/cm3), remarkable hydrophobicity, as evidenced by a water contact angle of 156°, high adsorption capacity up to 157.7 g/g for oil or organic solvents, and a high water-in-oil emulsion separation flux (9718 ± 45 L m−2 h−1) efficiently. Notably, the rigid cross-linking structure of PBOZ and the toughness structure of PAN make the aerogel exhibit synergistic strengthening and toughening effects. When the PAN/PBOZ fiber aerogel is compressed to 60 %, an outstanding recovery stability of its original size is displayed. While the springback of pure PAN fiber aerogel is poor under the same compression test condition. In conclusion, this study provides a preparation method and design concept of aerogel that can meet the requirements of low density, high toughness and high oil adsorption capacity. The rationally designed PAN/PBOZ aerogel shows significant potential for practical applications in treating oily and organic wastewater.

Sulfonate Functional Ultramicroporous Materials with Suitable Pore Size and Layer-Stacked Structure for C4 Olefins Purification.

Selective recognition of 1,3-butadiene from complex olefin isomers is vital for 1,3-butadiene purification, but the lack of porous materials with suitable pore structures results in poor selectivity and low capacity in C4 olefin separation. Herein, two sulfonate-functionalized organic frameworks, ZU-601 and ZU-602, are designed and show impressive separation performance toward C4 olefins. Benefiting from the suitable aperture size caused by the flexibility of coordinated organic ligand, ZU-601, ZU-602 that are pillared with different sulfonate anions could discriminate C4 olefin isomers with high uptake ratio: 1,3-butadiene/1-butene (207), 1,3-butadiene/trans-2-butene (10.1). Meanwhile, their layer-stacked structure enables the utilization of both intra- and interlayer space, enhancing the accommodation of guest molecules. ZU-601 exhibits record high 1,3-butadiene adsorption capacity of 2.90 mmol g-1 (0.5 bar, 298 K) among the reported flexible porous materials with high 1,3-butadiene/1-butene selectivity. The breakthrough experiments confirm their superior separation ability even for all five C4 olefin isomers, and the molecular-level structural change is well elucidated via powder, crystal analysis, and simulation studies. The work provides ideas toward advanced materials design with simultaneous high separation capacity and high separation selectivity for challenging separations.

Design and Machine Learning Prediction of In Situ Grown PDA-Stabilized MOF (UiO-66-NH2) Membrane for Low-Pressure Separation of Emulsified Oily Wastewater.

Significant progress has been made in designing advanced membranes; however, persistent challenges remain due to their reduced permeation rates and a propensity for substantial fouling. These factors continue to pose significant barriers to the effective utilization of membranes in the separation of oil-in-water emulsions. Metal-organic frameworks (MOFs) are considered promising materials for such applications; however, they encounter three key challenges when applied to the separation of oil from water: (a) lack of water stability; (b) difficulty in producing defect-free membranes; and (c) unresolved issue of stabilizing the MOF separating layer on the ceramic membrane (CM) support. In this study, a defect-free hydrolytically stable zirconium-based MOF separating layer was formed through a two-step method: first, by in situ growth of UiO-66-NH2 MOF into the voids of polydopamine (PDA)-functionalized CM during the solvothermal process, and then by facilitating the self-assembly of UiO-66-NH2 with PDA using a pressurized dead-end assembly. A stable MOF separating layer was attained by enriching the ceramic support with amines and hydroxyl groups using PDA, which assisted in the assembly and stabilization of UiO-66-NH2. The PDA-s-UiO-66-NH2-CM membrane displayed air superhydrophilicity and underwater superoleophobicity, demonstrating its oil resistance and high antifouling behavior. The PDA-s-UiO-66-NH2-CM membrane has shown exceptionally high permeability and separation capacity for challenging oil-in-water emulsions. This is attributed to numerous nanochannels from the membrane and its high resistance to oil adhesion. The membranes showed excellent stability over 15 continuous test cycles, which indicates that the developed MOFs separating layers have a low tendency to be clogged by oil droplets during separation. Machine learning-based Gaussian process regression (GPR) models as nonparametric kernel-based probabilistic models were employed to predict the performance efficiency of the PDA-s-UiO-66-NH2-CM membrane in oil-in-water separation. The outcomes were compared with the support vector machine (SVM) and decision tree (DT) algorithm. This efficiency includes various metrics related to its separation accuracy, and the models were developed through feature engineering to identify and utilize the most significant factors affecting the membrane's performance. The results proved the reliability of GPR optimization with the highest prediction accuracy in the validation phase. The average percentage increase of the GPR model compared to the SVM and DT model was 6.11 and 42.94%, respectively.

Synthesis of a composite Fe3O4@SiO2/poly(SMA-co-BA-co-BZMA-co-DMC) and evaluation of its oil-water separation performance

To obtain a demulsification material with convenient recovery, high oil-water separation capacity, and excellent reusability, Fe3O4@SiO2 core-shell particles and hydrophilic DMC were introduced into the acrylic ester-based polymer system to prepare a magnetic amphiphilic composite demulsifier, Fe3O4@SiO2/poly(SMA-co-BA-co-BZMA-co-DMC) (Fe3O4@SiO2/PAMCs-P). The molecular structure of Fe3O4@SiO2/PAMCs-P was characterized using FT-IR and XPS, while the morphology was observed using SEM. Additionally, the effects of TEOS, Fe3O4@SiO2 core-shell particles, and DMC dosage on the demulsification performance of the composites were discussed in detail. Fe3O4@SiO2/PAMCs-P exhibited excellent demulsification, oil-water separation, and reusability properties for CTAB-toluene emulsions. Under magnetic field conditions, Fe3O4@SiO2/PAMCs-P achieved saturated separation within 2 h with a separation efficiency of 97.9%. After five consecutive separations, the separation efficiency decreased to 39.1%, but it could be restored to 91.5% of the initial separation efficiency after desorption. These results indicate that Fe3O4@SiO2/PAMCs-P has valuable application potential in emulsified wastewater treatment.

A charged superhydrophilic-oleophobic anti-fouling sponges for rapid separation of O/W emulsions

The crude oil spillage and large-scale industrial release of oily effluents has led to significant ecological degradation and resource wastage. Traditional superwetting materials encounter intractable challenges for treating surfactant-stabilized oil–water emulsions, including trade-off effect of permeation flux and separation efficiency, and low emulsion processing life. These issues considerably impede advancements in oil–water separation industry. In order to enhance the demulsification durability of materials while ensuring high separation efficiency and flux, this work doped perfluorooctanoic acid (PFOA) onto the modified sponge surface with superhydrophilic charged surface, and a unique in-air superhydrophilic-oleophobic sponge was prepared. This special surface allows rapid water phase permeation yet offers remarkably more stable oleophobicity compared with traditional underwater oleophobic materials when processing a large amount of emulsions. The intrinsic oleophobicity endows the sponge outstanding fouling resistance and greatly increases the one-cycle emulsion treatment amount up to 1695 L·m−2. Moreover, the sponge's inherent long permeation channels and surface charge maintain a high separation efficiency of over 97 %. The large pores of the sponges and superhydrophilic surface provide a high permeation flux exceeding 40,000 L·m−2·h−1. The sponge with high separation efficiency, flux, and capacity marks a significant advancement, offering a promising strategy for superwetting material applications in oil-in-water emulsion separation fields.

Cephalopod inspired self-healing protein foams for oil-water separation

Cephalopods are remarkable creatures, captivating scientists with their advanced neurophysiology, complex behavior, and miraculously effective camouflage. Research into cephalopods has led to many discoveries in neuroscience, cell biology, and materials science. Specifically, squids provide us with remarkable self-healing Squid Ring Teeth protein, which is applied herein to extend the life span of foams. Despite the advantages of porosity in surface science applications, porosity impairs mechanical properties by making materials more prone to structural damage-which traditional polymeric foams also suffer from. Drawing inspiration from Squid Ring Teeth, we developed self-healing tandem repeat proteins to overcome these challenges. By leveraging porosity and self-healing properties inspired by Squid Ring Teeth, we created bioengineered protein foams with high separation capacity (5.1g g-1) and efficiency (≈94%). The foams healed entirely within minutes which regained over 100% strength after repair. These advances promise applications for efficient continuous water treatment through durable filter cartridges.

Multiscale analysis of the effect of the structural transformation of TBAB semi-clathrate hydrate on CO2 capture efficiency

TBAB semi-clathrate hydrate is considered as an environmentally friendly way to capture CO2. This study explored the effect of TBAB hydrate structure transformation on CO2–CH4 separation efficiency under the action of concentration and driving force. The experimental results showed that the gas consumption increased with increasing subcooling for the 10 wt% TBAB system but decreased for the 20 wt% TBAB system to a value that was much lower than that for the 10 wt% TBAB system. At 3 MPa and 12 K subcooling, the separation factor was 16.1 ± 1.2, the CO2 recovery was 63.3 ± 0.6%, and the hydrate phase CO2 concentration increased to 81.3 ± 0.8 mol%. A comparison of the hydrate structure showed that in the 20 wt% TBAB system, only type A hydrates were observed, whose growth was only dependent on the driving force. The larger driving force accelerated the formation of pure TBAB hydrate and inhibited the diffusion of CO2–CH4 guest molecules, reducing the separation effect. In contrast, under the 10 wt% TBAB system, except for the high driving force system, all systems exhibited the coexistence of type A and B hydrates with high gas storage and separation capacity, which can be considered for commercial applications.

Specific separation of flavonoids isomers by defect modulated metal-organic framework HKUST-1: Experiment and density functional theory analysis

Discovering and separating active monomers from natural products is an efficient way to develop new drugs, but faces the difficulty in complex and time-consuming separation process. Metal-organic frameworks (MOFs) are considered a promising separation strategy due to their molecular recognition properties, but their microporous nature poses challenges for capturing most natural compounds with molecule sizes larger than 20 Å. For the first time, this study proposed a simple and efficient approach to separate active monomeric components with larger diameters from structurally similar natural compounds by defect modulation strategy. In this study, defective HKUST-1 with hierarchical microporous/ mesoporous structures and Cu1+/Cu2+ mixed-valence sites was rapidly synthesized. The defective MOF demonstrated specific loading of silibinin A&B from silymarin containing seven structurally similar flavonoids within 5 min, and high separation capacity with the purity of ∼91.2% after primary separation. FTIR, XPS, and DFT calculation revealed the site competition mechanism for specific recognition and loading, where silibinin A&B preferentially acted on Cu2+ and Cu1+ clusters with the highest binding energy via hydrogen and coordination bonds, respectively. Compared to traditional separation techniques, the separation approach via defective MOF shows multiple advantages including high specificity, high separation efficiency, and easy to operate.

Detailed Speciation of Semi-Volatile and Intermediate-Volatility Organic Compounds (S/IVOCs) in Marine Fuel Oils Using GC × GC-MS.

Ship emissions contribute substantial air pollutants when at berth. However, the complexity and diversity of the marine fuels utilized hinder our understanding and mapping of the characteristics of ship emissions. Herein, we applied GC × GC-MS to analyze the components of marine fuel oils. Owing to the high separation capacity of GC × GC-MS, 11 classes of organic compounds, including b-alkanes, alkenes, and cyclo-alkanes, which can hardly be resolved by traditional one-dimensional GC-MS, were detected. Significant differences are observed between light (-10# and 0#) and heavy (120# and 180#) fuels. Notably, -10# and 0# diesel fuels are more abundant in b-alkanes (44~49%), while in 120# and 180#, heavy fuels b-alkanes only account for 8%. Significant enhancement of naphthalene proportions is observed in heavy fuels (20%) compared to diesel fuels (2~3%). Hopanes are detected in all marine fuels and are especially abundant in heavy marine fuels. The volatility bins, one-dimensional volatility-based set (VBS), and two-dimensional VBS (volatility-polarity distributions) of marine fuel oils are investigated. Although IVOCs still take dominance (62-66%), the proportion of SVOCs in heavy marine fuels is largely enhanced, accounting for ~30% compared to 6~12% in diesel fuels. Furthermore, the SVOC/IVOC ratio could be applied to distinguish light and heavy marine fuel oils. The SVOC/IVOC ratios for -10# diesel fuel, 0# diesel fuel, 120# heavy marine fuel, and 180# heavy marine fuel are 0.085 ± 0.046, 0.168 ± 0.159, 0.504, and 0.439 ± 0.021, respectively. Our work provides detailed information on marine fuel compositions and could be further implemented in estimating organic emissions and secondary organic aerosol (SOA) formation from marine fuel storage and evaporation processes.

Proteomics Evaluation of Semen of Clinically Healthy Beagle-Breed Dogs.

The objectives of the present work were to evaluate the semen of dogs by means of proteomics methods and to compare with proteomics results of the blood of the animals, in order to increase available knowledge on the topic and present relevant reference values for semen samples. Semen samples were collected from five Beagle-breed dogs. Reproductive assessment of the animals by means of clinical, ultrasonographic and seminological examinations confirmed their reproductive health. The sperm-rich fraction and the prostatic fraction of semen were processed for proteomics evaluation. LC-MS/MS analysis was performed by means of a LTQ Orbitrap Elite system. The technology combines high separation capacity and strong qualitative ability of proteins in biological samples that require deep proteome coverage. Protein classification was performed based on their functional annotations using Gene Ontology (GO). In blood plasma, semen sperm-rich fraction, and semen prostatic fraction, 59, 42 and 43 proteins, respectively, were detected. Two proteins were identified simultaneously in plasma and the semen sperm-rich fraction, 11 proteins in plasma and the semen prostatic fraction, and three proteins in the semen sperm-rich and prostatic fractions. In semen samples, most proteins were related to cell organization and biogenesis, metabolic processes or transport of ions and molecules. Most proteins were located in the cell membrane, the cytosol or the nucleus. Finally, most proteins performed functions related to binding or enzyme regulation. There were no differences between the semen sperm-rich fraction and prostatic fractions in terms of the clustering of proteins. In conclusion, a baseline reference for proteins in the semen of Beagle-breed dogs is provided. These proteins are involved mostly in supporting spermatozoan maturation, survival and motility, enhancing the reproductive performance of male animals. There appears potential for the proteomics examination of semen to become a tool in semen evaluation. This analysis may potentially identify biomarkers for reproductive disorders. This can be particularly useful in stud animals, also given its advantage as a non-invasive method.

Data-driven surrogate optimized and intensified extractive distillation process for clean separation of isopropanol from water: A sustainable alternative

Isopropanol (IPA) is an important chemical because of its wide use in chemical and related process industries. In the production of IPA, an important processing step is its recovery and purification. The objective of this paper is to analyze different processes to find an energy efficient and environmentally friendly alternative for clean separation of isopropanol from water. A six-step design methodology is employed, which starts with the conventional extractive distillation process (EDP). Design parameters of EDP are first optimized by using a proposed artificial neural network (ANN) based data-driven surrogate (ANNDS). Using the optimal EDP as a reference design, improvements (intensification and/or integration) are considered through the so-called distillation-membrane hybrid process (DMHP), by heat pump vapor recompression (HP-EDP-I and HP-EDP-II), and dividing wall column without (E-DWC) and with (HP-E-DWC) heat pump, respectively. The results show that DMHP can be considered as a retrofit option with an energy reduction of 2.45% for the whole EDP. As compared to EDP, energy consumed in HP-EDP-I, HP-EDP-II, E-DWC, and HP-E-DWC can be reduced by 37.7%, 44.1%, 40.0%, and 56.4%, respectively. Moreover, CO2 emission is reduced by 42.6%, 50.4%, 40.0%, and 59.0%, respectively. Therefore, HP-E-DWC process is found to be the most sustainable alternative for the clean separation of isopropanol from water among the proposed processes. With further consideration of economic performance, HP-E-DWC is found to have the best performance with high separation capacity (>37500 kg/h), while E-DWC is found to be a favorable choice for a small plant with low capital cost and intermediate environmental impacts.

Bio-Based Porous Aerogel with Bionic Structure and Hydrophobic Polymer Coating for Efficient Absorption of Oil/Organic Liquids.

Increasing contamination risk from oil/organic liquid leakage creates strong demand for the development of absorbents with excellent hydrophobicity and absorption capacity. Herein, bagasse was carbonized to form porous char with a special structure of array-style and vertically perforated channels, and then the activation process enlarged the pore volume of the char. With the cooperation of low-surface-energy polydimethylsiloxane and diatomaceous earth particles, the modified activated carbon aerogel (MACA) was fabricated by modifying the surface coating and mastoid structure on the bagasse char. Moreover, the MACA demonstrates high porosity oil-water separation, hydrophobicity, and considerable absorption capacity (4.06-12.31 g/g) for gasoline and various organic solvents. This work converts agricultural waste into an efficient porous adsorbent, offering a scalable and commercially feasible solution to solving the leakages of oil/organic solvents.

Targeted profiling of rodent unconjugated bile acids using GC-MS to determine the influence of high-fat diet.

Unconjugated bile acids (BAs) have gained more attention than conjugated BAs in the association studies among diet, gut microbiota, and diseases. GC-MS is probably a good choice for specialized analysis of unconjugated BAs due to its high separation capacity and identification convenience. However, few reports have focused on the rodent unconjugated BAs using GC-MS, and the main library for identification has not included rodent-specific BAs. We developed a GC-MS method for targeted profiling of eight main unconjugated BAs in rodent models, which showed excellent performance on sensitivity, reproducibility, and accuracy. Quantitative reproducibility in terms of relative standard deviation (RSD) was in the range of 2.05-2.91%, with detection limits of 3-55 ng/mL, quantitation limits of 9-182 ng/mL, and the recovery rate of 72-115%. All the calibration curves displayed good linearity with correlation coefficient values (R2 ) more than 0.99. Using the established method, the influence of high-fat diet on the metabolism of unconjugated BAs was revealed. Significant increase in fecal unconjugated BAs induced by high-fat diet would be a potential risk to gut inflammation and cancer. The study provides a convenient and targeted GC-MS method for specialized profiling of rodent unconjugated BAs in physiological and pathological studies.

Facile Construction and Fabrication of a Superhydrophobic and Super Oleophilic Stainless Steel Mesh for Separation of Water and Oil.

The fluoride-free fabrication of superhydrophobic materials for the separation of oil/water mixtures has received widespread attention because of frequent offshore oil exploration and chemical leakage. In recent years, oil/water separation materials, based on metal meshes, have drawn much attention, with significant advantages in terms of their high mechanical strength, easy availability, and long durability. However, it is still challenging to prepare superhydrophobic metal meshes with high-separation capacity, low costs, and high recyclability for dealing with oil–water separation. In this work, a superhydrophobic and super oleophilic stainless steel mesh (SSM) was successfully prepared by anchoring Fe2O3 nanoclusters (Fe2O3-NCs) on SSM via the in-situ flame synthesis method and followed by further modification with octadecyltrimethoxysilane (OTS). The as-prepared SSM with Fe2O3-NCs and OTS (OTS@Fe2O3-NCs@SSM) was confirmed by a field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectrometer (XPS), and X-ray diffractometer (XRD). The oil–water separation capacity of the sample was also measured. The results show that the interlaced and dense Fe2O3-NCs, composed of Fe2O3 nanoparticles, were uniformly coated on the surface of the SSM after the immerging-burning process. Additionally, a compact self-assembled OTS layer with low surface energy is coated on the surface of Fe2O3-NCs@SSM, leading to the formation of OTS@Fe2O3-NCs@SSM. The prepared OTS@Fe2O3-NCs@SSM shows excellent superhydrophobicity, with a water static contact angle of 151.3°. The separation efficiencies of OTS@Fe2O3-NCs@SSM for the mixtures of oil/water are all above 98.5%, except for corn oil/water (97.5%) because of its high viscosity. Moreover, the modified SSM exhibits excellent stability and recyclability. This work provides a facile approach for the preparation of superhydrophobic and super oleophilic metal meshes, which will lead to advancements in their large-scale applications on separating oil/water mixtures.

Highly permeable and dye-rejective nanofiltration membranes of TiO2 and Bi2S3 double-embedded Ti3C2Tx with a visible-light-induced self-cleaning ability

To conquer the trade-off dilemma of the nanofiltration membranes for both high permeability for water and high rejection for pollutants has long been highly concerned. In this work, TiO2 and Bi2S3 nanoparticles were evenly dispersed successively into the interlayers of Ti3C2Tx nanosheets, and then filtered onto cellulose acetate support membranes. The as-obtained composite membranes exhibited a maximum water flux of 374.4 L m−2 h−1 bar−1, and a high rejection ratio for RhB, GR, MB and BSA at 97.8–100%, apparently higher than those of the Ti3C2Tx and the related membranes in literature. Such a high separation capacity was found quite stable for various dye-containing aqueous solutions, even in a high salinity environment of 5 wt% NaCl. Interestingly, 25% NaCl salt was also rejected accompanying the almost complete rejection of dye pollutants. After the filtering process, the membrane fouling of fouled Ti3C2Tx/TiO2/Bi2S3 membranes was verified quite lower than that of fouled Ti3C2Tx/TiO2 and Ti3C2Tx membranes. Furthermore, the flux recovery rate of the fouled composite membrane could reach 92.1% after washing under visible light, which could be ascribed to the composition of heterojunction causing the red shift of diffuse reflectance UV–vis spectra and the narrowing of the band gap. This study provides a new idea for the preparation of highly permeable and rejective nanofiltration membranes, and lays a foundation for its high-capacity dye removal applications.

Fractionation of monovalent ions from seawater brine via softening nanofiltration and selective electrodialysis: Which is better?

In this study, a direct and systematic comparison of softening nanofiltration (SNF) and selective electrodialysis (SED) processes was made for the first time. First, the effects of key operating parameters of the two processes were investigated regarding monovalent-ion separation performance. The optimal operating pressure and feed flow rate for SNF were 2.4 MPa and 1000 L/h, while the optimal cell-pair voltage and replenishment flow rate for SED were 0.8 V and 6 L/h, respectively. Subsequently, two-stage SNF and two-stage SED were conducted based on their optimization. The concentration and purity of NaCl in two-stage SNF permeate were 32.03 g/L and 93.38%, while those in two-stage SED mixed concentrate were 183.04 g/L and 95.20%, respectively. Finally, a valid and fair metric was established to make a thorough comparison of the two membrane processes for the seawater brine reclamation. The results indicated that the SNF process was more suitable for only NaCl fractionation from seawater brine due to its relatively low specific energy consumption of NaCl in the purified brine and its high monovalent-ion separation capacity. However, SED should be recommended preferentially if the NaCl concentration effect is considered simultaneously. This investigation could provide insight and guidance for applications of each technology.

MoS2/CoFe2O4 heterojunction for boosting photogenerated carrier separation and the dominant role in enhancing peroxymonosulfate activation

• MoS 2 /CoFe 2 O 4 (MC) had high carriers separation capacity and migration efficiency. • Photoinduced electron-hole pairs played important roles in PMS activation. • Norfloxacin over MC/PMS/Vis could be completely degraded after only 15 min. Utilizing peroxymonosulfate (PMS) to produce a catalytic system in which multiple active species coexist is a promising tactic to enhance the oxidation capacity of photocatalytic systems. Here, a MoS 2 /CoFe 2 O 4 heterojunction (MC) was constructed for PMS activation to degrade norfloxacin (NFX) in water under visible light irradiation. MC exhibited a higher visible light response, excellent separation capacity and migration efficiency of photoinduced charge, and superior catalytic performance in the MC/PMS/Vis system for the decomposition of NFX. After only 15 min of reaction, the degradation efficiency of NFX by the MC/PMS/Vis system reached 95.0%. This degradation efficiency was far greater than that of pure MoS 2 and CoFe 2 O 4 under identical conditions. In addition, after the 5th reuse, the degradation efficiency still exceeded 93.0%. The separation and transfer mechanism of photogenerated carriers was explored in detail using photoelectrochemical and X-ray photoelectron microscopy (XPS). More importantly, the NFX degradation pathway, intermediate toxicity assessment, and MC/PMS/Vis system reaction mechanism were proposed. Therefore, this work might provide new insight into the mechanism by which MC activates PMS under visible light, which is of importance for creating environmentally friendly catalytic methods for the efficient degradation of organic wastewater.

Investigation of heterojunction between α-Fe2O3/V2O5 and g-C3N4 ternary nanocomposites for upgraded photo-degradation performance of mixed pollutants: Efficient dual Z-scheme mechanism

In this present work, a g-C3N4 decorated dual Z-scheme α-Fe2O3 and V2O5 heterojunction of magnetically recoverable GFV (g-C3N4/α-Fe2O3/V2O5) composite was rationally synthesized using facile calcination and hydrothermal approach. The crystal structure, surface morphology, chemical composition and optical properties of the as-obtained composite photocatalysts (PCs) were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra high-resolution scanning electron microscopy (HR-SEM, high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) measurement, UV-Vis diffuse reflectance spectra (DRS) and photoluminescence (PL) analyses respectively. Benefiting from these structural and compositional features, the optimum GFV heterostructured PCs sample revealed that the superior photo-degradation performance of methyl yellow (MY) and methylene blue (MB) mixed dye under visible-light, while the degradation rates were 93.4% for MY and 87.5% for MB dye at 90 min, respectively. Moreover, the enhanced photo-degradation performance of GFV composite PCs displayed an extended visible-light fascination due to lower bandgap, reduced recombination rates, high charge separation and good charge transfer capacity with the efficient dual Z-scheme heterojunction. Meanwhile, high photo-degradation stability is continued after five successive reusability tests. A possible photo-degradation mechanism of dual Z-scheme charge transfer paths was also been proposed. This study is also capable of emerging visible-light active facile heterojunction photocatalysts for various organic pollutants removal with great efficiency.