Optimal Separation Performance Research Articles

Bimetallic MOF-74-based mixed matrix membrane for efficient CO2 separation

The bimetallic Ni(Zn)-MOF-74 nanoparticles were fabricated by the metal substitution method and doped into a polyether-polyamide block copolymer (Pebax 1657) matrix to obtain mixed matrix membrane (MMM) for CO2/CH4 separation. The pore structure and chemical properties of Ni(Zn)-MOF-74 nanoparticles were controlled by changing the molar ratio of Ni/Zn, and the effect of heterometallic on the gas separation performance of MMMs was studied. In particular, when the molar ratio of Ni/Zn was 2:1, the Pebax/Ni(Zn)-MOF-74-21 MMMs has the optimal CO2 separation performance. The main reason was that Ni(Zn)-MOF-74-21 has the smallest pore size (0.68 nm) and abundant CO2 adsorption sites, which could effectively prevent the entry of CH4 molecules after preferentially adsorbing one or two CO2 molecules, and improve the selectivity of CO2/CH4 molecules. Furthermore, the unreplaced pore size of 1.48 nm and the increased polymer chain spacing in Ni(Zn)-MOF-74-21 nanoparticles could provide a fast transport channel for CO2 and improve the permeability of MMMs. The developed Pebax/Ni(Zn)-MOF-74-21 MMMs loaded with 2 wt% filler displayed a CO2/CH4 selectivity of 33.7 and a high CO2 permeability of 719.9 barrer, exceeding the gas separation performance of many previously reported MOF-74-based MMMs. The results showed that the development and design of bimetallic organic framework was an important way to obtain high performance MOF-74-based MMM.

Thermodynamic analysis of a novel gas separator based on molecular exchange flow

An energy analysis model and several evaluation indexes are established for a novel gas separator employing molecular exchange flow as working principle. The influences of several important factors on energy consumption and thermal efficiency are investigated. As temperature difference increases, both energy consumption and thermal efficiency rise linearly. As Knudsen number increases, total work decreases while minimum separation work and thermal efficiency initially increase and subsequently decrease. When inlet velocity increases, total work increases but minimum separation work and thermal efficiency go down. Furthermore, both energy consumption and thermal efficiency initially rise and then decline with an increasing mole fraction of the lighter molecular weight component. The results indicate that energy consumption and separation performance should be taken into consideration when selecting temperature differences. In addition, it is preferable to choose the Knudsen number corresponding to optimal separation performance and the intermediate value for component mole fraction. Moreover, it had better employ a lower inlet velocity as long as the separation requirements are satisfied. This study presents a method to optimize the performance of the novel separator based on molecular exchange flow from the perspective of energy conversion and utilization.

Multi-objective optimization of hydrocyclones using meta-heuristic algorithms and preference-informed decision-making

Previous hydrocyclone optimizations often overlooked crucial objectives interactions, thereby weakening the overall system performance. This study presents a framework that integrates meta-heuristic algorithms with preference-informed decision-making to simultaneously optimize key performance objectives. Meta-heuristics identify comprehensive Pareto-optimal sets, while preference-informed decision-making evaluates each solution's overall separation performance according to specific separation preferences. Supported by computational fluid dynamics, the study quantifies the trade-off between optimal overall separation performance and pressure drop, enabling the attainment of optimal overall separation performance at any pressure drop within the Pareto-optimal set. Among the evaluated algorithms, the strength Pareto evolutionary algorithm 2 (SPEA2) stands out for its exceptional diversity and convergence. With this framework, the study circumvents excessive compromises on neglected but crucial objectives, especially highlighting the significant adverse effects of overlooking water split or cut size. Overall, this study provides an integrated approach for developing energy-efficient hydrocyclones that maximize overall separation performance tailored to specific separation requirements.

Constructing bio-inspired anion channels by dual-ligand MOF in membranes for efficient CO2 separation

One of the biggest challenges of Pebax-based membranes is how to simultaneously achieve high CO2 permeability and selectivity. Hence, three-dimensional L-histidine@zeolitic imidazole framework-8 (His@ZIF-8 (X)) was synthesized as dual-ligand metal-organic framework (MOF), and it was incorporated into the Pebax 1657 matrix to fabricate mixed matrix membranes (MMMs) for efficient CO2 separation. The three-dimensional His@ZIF-8 (X) with abundant His mimicked anion transport protein, and it constructed bio-inspired anion transport channels. His@ZIF-8 (X) played important functions when it was incorporated into the MMMs: the bio-inspired active sites of His@ZIF-8 with the Zn2+ bonded to three Hmim and one water molecule had similar function with the active sites in carbonic anhydrase (CA), which can catalyze CO2 into water-soluble bicarbonate (HCO3−). Subsequently, the bio-inspired anion transport channels allowed HCO3− to rapidly transport, because they had His residues that can form anion-dipole interactions with HCO3− in His@ZIF-8 (X). Therefore, Pebax 1657/His@ZIF-8 (X) MMMs were endowed with the excellent separation performance due to the bio-inspired anion transport channels constructed by His@ZIF-8 (X). In particularly, MMM contained 4 wt% His@ZIF-8 (12.5) achieved the optimal separation performance with a CO2 permeability of 541 ± 9 Barrer and CO2/CH4 selectivity of 35 ± 0.6. The work implies that the construction of the bio-inspired anion transport channels within MMMs was a potential strategy for efficient CO2 separation.

Enhanced gas separation performance for H2 purification using MIL-68(ln)-nh2/PES mixed-matrix membranes

The growing demand for sustainable and efficient gas separation technologies has prompted the exploration of advanced materials to enhance the gas permeability and selectivity. Polyethersulfone (PES) membranes are widely used in gas separation, gas upgrading, and clean energy production owing to their environmental friendliness and low cost. However, their gas permeability and selectivity can be further improved for commercial application. This study explored the incorporation of 10 wt % of MIL-68(ln)-NH2 into PES membranes using a phase-inversion approach to enhance gas permeability and selectivity. The morphological, structural, and thermal properties of the resulting MOF/PES membrane were characterized using SEM, AFM, BET, XRD, FTIR, and TGA-DTG. Gas permeation experiments were conducted using different gases (CO2, N2, CH4, and H2) under different heating conditions (20–60 °C) to evaluate the gas permeability and selectivity of the MOF/PES membrane. The results showed that the incorporation of MOF into the mixed matrix membrane (MMMs) led to a 9% increase in porosity, 87% reduction in roughness, and 32% decrease in pore size compared to neat PES membranes. Significant changes in the morphology, crystallinity, and thermal stability were observed, with notable improvements of up to 22%. Moreover, the MOF/PES membrane exhibited high gas permeability (CO2 = 124656, N2 = 83650, CH4 = 159298, and H2 = 427075 Barrer) and selectivity (H2/N2 = 5.7, H2/CO2 = 4, CH4/N2 = 2, and CH4/CO2 = 1.7) for flammable gases. The optimal gas separation performance was observed at 20 °C and 60 °C for H2/N2 and H2/CO2 separation, respectively. These findings demonstrate the potential of MOF-based PES membranes for gas separation applications, particularly in H2 purification.

Covalently assembling multi-dimensional carbon-based nanoclay composites via ionic liquid linkers into PVA membrane for molecular separation

The application of membrane-based separation technology in purifying azeotropic solutions plays a crucial role in minimizing energy consumption during reactive distillation. The strategic integration of multi-dimensional structural composites within mixed matrix membranes (MMMs), characterized by a robust framework and efficient molecular transport channels, poses challenges but demonstrates significant potential for advancing the development of high-performance membrane fabrication. Herein, we proposed a novel strategy to covalently assemble halloysite nanotubes (HNTs) and graphene oxide (GO) using ionic liquids (ILs) as linkers. When incorporated into the polyvinyl alcohol (PVA) matrix, the ILs@HNTs@GO (IHGO) composites exhibit excellent interfacial compatibility, and ILs also enhanced the composite’s selective transfer ability to water molecules. The optimal separation performance for pervaporation dehydration from a ternary solution was respectively 2.57 (selectivity) and 1.74 (permeability) times higher than those of the pristine PVA membrane. The structural stability of the MMMs and their separation mechanism has been comprehensively validated by adjusting the content of GO in IHGO composites and conducting simulations. This study holds significant theoretical and practical implications for organic compounds purification, while simultaneously paving new avenues for the fabrication of structurally robust and high-performance MMMs with optimal filler effectiveness.

Incorporation of dendritic silica nanoparticles for the preparation of high‐performance thin‐film nanocomposite membranes

AbstractThe development of thin‐film nanocomposite (TFN) membranes with high performance is conducive to efficient desalination and wastewater treatment. In this work, dendritic mesoporous silica nanoparticles (DLSiO2) were synthesized by a dual‐templating strategy. Afterward, they were introduced into the aqueous phase to fabricate TFN membranes via in situ interfacial polymerization (IP) reaction. Powerful techniques as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Nano zetasizer‐DLS, x‐ray photoelectron microscopy, electrokinetic analyzer, and contact angle were used in the characterization of dendritic structures and nanocomposite membranes. Results revealed that DLSiO2 with special structural characteristics can effectively regulate the IP process, promoting the enhancement of the crosslinking degree, surface hydrophilicity, and surface negative charge of polyaimde (PA) selective layers. It is also beneficial for constructing extra water channels within the PA selective layer to boost the transport of water molecules. As a consequence, the prepared TFN membrane with 0.3 mg/mL DLSiO2 exhibits optimal separation performance and good pressure resistance, acid–base resistance, and anti‐fouling properties. It also exhibited a water permeability of 4.17 L m−2 h−1 bar−1 (increased by 61.7% compared with thin film composites (TFC) membrane) and a NaCl rejection of 99.0%, which were better than those of TFN membranes prepared by introducing other types of silica in other studies.

Enhanced coarse coal slime separation in a gravity–flotation coupled separator with up-flow feeding and dual-concentrate

ABSTRACT A gravity – flotation coupled separator with up-flow feeding and dual-concentrate was developed to improve the recovery and selectivity in coarse coal slime separation. The separator combines flotation, cyclone separation, and gravity sedimentation. The optimal separation performance was achieved under the following conditions: slurry concentration = 100 g/L, feed flow rate = 4.411 m3/h, circulating rate = 3.125 m3/h, fifigfeeding air flow rate = 2 m3/h, frother dosage = 150 g/t and collector dosage = 1500 g/t. Two concentrates were obtained with ash contents of 7.48% and 11.56%. The partition coefficients of the 0.75–1 and 0.5–0.75 mm fractions were 88.42% and 95.92%, respectively, indicating the satisfactory recovery of coarse particles. The ash content in the tailings was 66.08%, indicating good selectivity. The diverging flow under the froth layer produced a coarse concentrate, which improved the recovery of the concentrate and reduced the flotation concentrate ash content. The total recovery of the concentrate blended with the + 0.25 mm fraction of diverging flow was 84.00%. Both up-flow and cyclone separation are beneficial for coarse particle recovery. The static separation cone is instrumental in improving the separation effect. Therefore, this wide-sized coal-slime separator facilitates the effective separation of both coarse and fine particles.

Thermally rearranged OH-containing polyimide composite membranes with enhanced gas separation performance and physical aging resistance

Gas separation membranes play a pivotal role in various industrial processes, demanding continuous improvement in their efficiency and durability. This study focuses on thin-film composite (TFC) membranes based on polyimide, utilizing a hydroxyl-containing polyimide selective layer for its processability and selectivity. A complete and smooth surface for the selective layer in the composite membranes was achieved by exclusively selecting a 10% concentration of the polyimide spin-coating solution. Subsequent thermal rearrangement at 430°C induced the formation of a rigid polybenzoxazole structure, enhancing gas permeance. Optimal separation performance was achieved through a two-hour rearrangement, resulting in a more than 30-fold increase in gas permeance while preserving selectivity. The study also delved into anti-physical aging performance. The thermally treated PI-10 wt%−2 h membrane exhibited a 10% reduction in CO2 and O2 permeance over 90 days, with O2/N2 and CO2/N2 selectivities nearly maintaining their initial levels. This research provides valuable insights for the development of efficient and durable gas separation membranes.

Leveraging Diffusion Kinetics to Reverse Propane/Propylene Adsorption in Zeolitic Imidazolate Framework-8.

The separation challenge posed by propylene/propane mixtures arises from their nearly identical molecular sizes and physicochemical properties. Metal-organic frameworks (MOFs) have demonstrated potential in addressing this challenge through the precision tailoring of pore sizes and surface chemistry. However, introducing modifications at the molecular level remains a considerable hurdle. This work presents an approach to reversibly tune the propylene/propane adsorption preference in zeolitic imidazolate framework-8 (ZIF-8) by manipulating the particle size and gas flow rate. Systematically increasing the ZIF-8 crystals from 9 to 224 μm restricts propane diffusion, thereby reversing its preferential adsorption over propylene. Furthermore, raising the gas flow rate of mixed propylene/propane shifts the rate-determining breakthrough step from thermodynamic equilibrium to kinetics, again reversing the adsorption preference in a particular ZIF-8 sample. We propose "dynamic selectivity (Sd(t))" as a concept that incorporates both thermodynamic and kinetic factors to elucidate these unexpected findings. Moreover, the driving force equation, grounded on the concept of Sd(t), has improved the precision and stability of the computational simulation for fixed-bed adsorption processes. This work underscores the potential of diffusion-based modulation, implemented through manageable external changes, as a viable strategy to optimize separation performance in porous adsorbent materials.

Synthesis and characterization of high-flux ZIF-90/poly-dimethyldiethoxysilane (PDMDES) mixed matrix membrane for enhanced pervaporation recovery of alcohols

In the present research, micron-sized zeolitic imidazolate framework-90 (ZIF-90) particles were synthesized utilizing an adapted synthesis route and subsequently incorporated into the poly-dimethyldiethoxysilane (PDMDES) polymer to fabricate ZIF-90/PDMDES mixed matrix membrane (MMM) with an objective to achieve enhanced pervaporation performance for the efficient separation of alcohols from aqueous solutions. Comprehensive characterization techniques were employed to investigate the properties of the ZIF-90 particles and the newly fabricated ZIF-90/PDMDES MMMs. Encouraging findings revealed that the incorporation of microporous ZIF-90 particles led to notable enhancements in hydrophobicity, alcohol affinity, and thermal stability of the MMMs. Notably, a distinctive cross-sectional morphology of the ZIF-90/PDMDES MMMs were observed at lower ZIF-90 loadings, a phenomenon attributed to the disparity between the ZIF-90 particle size and the inherent thickness of the PDMDES layer. Systematic evaluations were conducted to ascertain the influence of ZIF-90 loadings, feed concentration, and operational temperature on the pervaporation performance of ZIF-90/PDMDES MMMs. Accordingly, the optimal separation performance was obtained at the ZIF-90 loading of 5 wt% when separating ethanol from 5 wt% ethanol aqueous solution at 40 °C, yielding an impressive total flux of 6.51 kg∙m−2 h−1, a separation factor of 7.29, a PSI of 40.95 kg∙m−2 h−1, and an ethanol permeability of 7.45 × 104 Barrer.

Amino acid-bonded Ti3C2Tx MXene nanofiltration membranes with superior antifouling property for enhanced water purification

MXene nanosheets have been identified as promising building blocks for high-performance nanofiltration (NF) membranes in water purification. Herein, we report a series of amino acid-bonded Ti3C2Tx MXene membranes with enhanced NF performance and antifouling properties via glycine (Gly), l-glutamic acid (L-Glu), l-lysine (L-Lys) or l-cysteine (L-Cys) modification. The physicochemical properties, separation performances and anti-fouling behaviors of the pure Ti3C2Tx MXene membrane, Gly-, L-Glu-, L-Lys- and L-Cys-bonded Ti3C2Tx MXene membranes were comparatively investigated. The stable Ti–N bonds were found between the amino acids and the MXene nanosheets and different amino acids lead to different properties of the corresponding membranes. While maintaining ultra-high rejections to various organic dyes, all the amino acid functionalized membranes exhibited enhanced water permeability (7.17–13.11 L·m−2·h−1·bar−1) compared with that of the pure MXene membrane. Importantly, the Gly-bonded membrane showed the optimal separation performance with high salt rejections of 86.28%, 81.36%, 72.88% and 66.82% to MgSO4, MgCl2, Na2SO4 and NaCl, respectively, and the membrane also exhibited superior anti-fouling property with a flux recovery rate of 80.59% to bovine serum albumin (BSA). The separation mechanism was further revealed which may offer a simple yet efficient way for enhancing 2D MXene-based NF membranes.

Fabrication of CeO2/carbon molecular sieving membranes for enhanced O2/N2 gas separation

In this study, CeO2/carbon composite molecular sieving membranes (CMSMs) were prepared on carbonaceous plate supports using polyimide as precursor and cerium oxide (CeO2) as fillers via spin-coating method and pyrolysis. The microstructure and properties of CMSMs were analyzed by thermogravimetric analysis, infrared spectroscopy, X-ray diffraction, scanning electron microscope, particle size distribution and gas permeation test. The influence of the filler amount of CeO2 on the microstructure and performance of CMSMs was mainly investigated. The results showed that the incorporation of CeO2 significantly enhanced the graphitization degree and structural compactness of CMSMs. The optimal gas separation performance of CMSMs reaches to 16.3 for O2/N2 selectivity and 240.3 Barrer for O2 permeability, which is fabricated by the precursor containing CeO2 content of 0.2 % under the permeation condition of 30 °C and 0.02 MPa.

Recovering cobalt from cobalt oxide ore using suspension roasting and magnetic separation technique

Cobalt ore is a scarce resource in China, often associated with iron ore, and it is well known that its separation and effective recovery are extremely difficult. In this paper, cobalt oxide ore is used as raw material and reduced by suspension roasting method at the atmosphere of H2. Magnetic separation is carried out to obtain cobalt (Co) and Fe concentrate. The experimental results show that the optimal magnetic separation performance of cobalt oxide ore is achieved at 650 °C and 30 % H2 concentration. The Co and Fe concentration are obtained synchronously with the grade of 7.32 % and 62.13 % respectively. X-ray diffraction (XRD) and scanning electron microscope (SEM) reveals that the phase of cobalt oxide ore in H2 roasting process is transformed into CoO→Co and Fe2O3→Fe3O4. The surface of the sample appears cracks after roasting. The vibrating sample magnetometer (VSM) test reflects the magnetic changes of minerals that the optimum roasting condition leads to an increased magnetism. The specific surface and fracture structure are analyzed to illustrate the specific surface area and pore volume of the particles decrease and the average pore size increases as the roasting temperature increases. In general, reduction roasting of cobalt ore makes it possible to recover Co and Fe simultaneously, following by magnetic separation. The beneficiation efficiency is improved along with the reduced cost.

Integrating two-dimensional MXene fillers into nanocellulose for the fabrication of CO2 separation membranes

To achieve high capability mixed matrix membranes for CO2 separation, it is vital to construct the suitable transport channels to enhance the diffusivity-enabled selectivity as well as an excellent affinity toward target gas molecules to increase the solubility-based selectivity. Herein, composite membranes were constructed by integrating two-dimensional MXene nanosheets into a carboxylated nanocellulose matrix. The carboxyl-rich cellulose interacts with the surface groups of MXene, which contributes to a superior interface compatibility and repairs the non-selective voids. In particular, one-dimensional nanocellulose can intercalate into MXene laminates to regulate the interlayer spacing and suppress the re-stacking of MXenes. The resulting MC-3 membrane (with a MXene loading of 15.4 wt%) possesses the optimal separation performance, bearing a CO2 permeability of 156.7 Barrer with ideal selectivities of 47.8 for CO2/CH4 and 42.6 for CO2/N2. For the mixed gas separation, the MC-3 membrane exhibits separation factors of 48.5 and 55.3 for CO2/N2 and CO2/CH4, respectively. This excellent separation performance is resulted from the enhanced interfacial property, suitable MXene channel size and good CO2-solubility of nanocellulose.

An efficient immersing strategy for enhancing the separation performance of microfiltration carbon membranes for oily wastewater

Here, an immersing strategy was designed to modify the porous structure of microfiltration carbon membranes (MFCMs) made by the pyrolysis of phenolic resin-based plates. The thermal stability of precursors, the functional groups, porous structure, microcrystalline structure, microscopic morphology and surface wettability of MFCMs were characterized by TGA, FT-IR, XRD, SEM, TEM and water contact angle, respectively. The effects of the concentration of immersing solution, soaking time and operational conditions on the separation performance of MFCMs for oily wastewater were investigated. In addition, the anti-fouling ability of the MFCMs was further examined. The results showed that the average pore size and porosity of MFCMs decreased after immersing modification. When the modification condition was adopted at the immersing solution concentration of 3% and soaking time of 60 s, the resultant MFCMs exhibited the minimum average pore size of 0.13 μm and a porosity of 31.96%. At the same time, the optimal separation performance was achieved at 99.85% for oil rejection and 392.16 Kg/m2•h•MPa for water permeation flux. In addition, the oil rejection almost remains intact during antifouling ability test, except for a slight drop trend of water permeation flux. It is evident that the facile immersing protocol holds a promise for effectively modifying MFCMs in the treatment of oily wastewater.

Ionic Liquids Functionalized MOFs for Adsorption.

Metal-organic frameworks (MOFs) and ionic liquids (ILs) represent promising materials for adsorption separation. ILs incorporated into MOF materials (denoted as IL/MOF composites) have been developed, and IL/MOF composites combine the advantages of MOFs and ILs to achieve enhanced performance in the adsorption-based separation of fluid mixtures. The designed different ILs are introduced into the various MOFs to tailor their functional properties, which affect the optimal adsorptive separation performance. In this Perspective, the rational fabrication of IL/MOF composites is presented, and their functional properties are demonstrated. This paper provides a critical overview of an emergent class of materials termed IL/MOF composites as well as the recent advances in the applications of IL/MOF composites as adsorbents or membranes in fluid separation. Furthermore, the applications of IL/MOF in adsorptive gas separations (CO2 capture from flue gas, natural gas purification, separation of acetylene and ethylene, indoor pollutants removal) and liquid separations (separation of bioactive components, organic-contaminant removal, adsorptive desulfurization, radionuclide removal) are discussed. Finally, the existing challenges of IL/MOF are highlighted, and an appropriate design strategy direction for the effective exploration of new IL/MOF adsorptive materials is proposed.

Influence of flow straightener structure on energy separation performance of Ranque-Hilsch vortex tube based on energy and exergy analyses

The energy separation characteristics of vortex tube installed with flow straightener were experimentally investigated for better promotion of the application of vortex tube in the improvement of energy efficiency and sustainability. Systematic evaluation of the vortex tube with straightener was performed by applying a combined method of energy as well as exergy analysis, and the temperature separation process facilitated by the flow straightener was analyzed in depth. The effects of cold mass fraction (μc = 0.2–0.8), blades number (N = 0, 2, 4, 6 and 8), diameter ratio (ε = 0, 0.2, 0.4, 0.6 and 0.8), blade angle (θ = 0°, 30°, 60° and 90°) and installation position (Ls/L = 0.25, 0.45, 0.65 and 0.85) on cold and hot temperature differences, coefficient of performance, exergy efficiency and internal temperature field were investigated experimentally. The results show that as the blades number, blade angle and installation position increase, the cold and hot temperature difference and coefficient of performance first ascend and then descend. The presence of a hole in the center of flow straightener weakens the energy separation performance of vortex tube. A flow straightener with 4 blades, 0 diameter ratio, 60° blade angle and 0.65 installation position produces optimum energy separation performance and exergy efficiency.

Constructing mixed matrix membranes for CO2 separation based on light lanthanide fluoride nanosheets with mesoporous structure

The incorporation of porous nano-fillers into mixed matrix membranes (MMMs) has a great impact on CO2 separation. In this study, a series of F-Ln (Ln is the Light Lanthanide, Ln = La, Ce, Pr, Nd) nanosheets with mesoporous structure was fabricated as a filler in Pebax®1657 matrix to improve the performance of CO2 separation. F-Ln nanosheets are uniformly distributed in the membrane and the mesoporous structure can construct multiple channels for CO2 fast transport in Pebax/F-Ln MMMs. The pore diameter of nanosheet is in order: F-La > F-Ce > F-Pr > F-Nd, and the smaller pore diameter of nanosheets is beneficial to improve the CO2 separation performance. In humidified conditions, Pebax/F-Nd-6 MMMs show optimum separation performance among MMMs, and the CO2 permeability is up to 1265 Barrer and CO2/CH4 selectivity is 36.7, which are 2.3 times and 1.9 times higher than pure Pebax and approaches 2019 upper bound. Meanwhile, to demonstrate the potential universal applicability of F-Ln nanosheets in CO2 separation, XLPEO/F-Ce MMMs were fabricated to separate CO2/N2 and the performance exceeds the 2019 upper bound. The efficient CO2 separation performance of 2D F-Ln nanosheets with mesoporous structure in membranes reveals the potential application of these nanosheets in industrial CO2 separation.

Mirror-Stamping: A new TLC-SERS method for color authentication

Adulteration of natural colorants with artificial ones compromises the authenticity, quality, and safety of food products. It is significant for food companies to check the raw colorant ingredients to avoid potential adulteration. Combining thin-layer chromatography (TLC) and surface-enhanced Raman spectroscopy (SERS) is a promising colorant separation and detection approach. Herein, we developed a novel and simple TLC-SERS approach based on silver mirror-stamping, which was achieved by pressing a layer of aggregated silver nanoparticles on top of the target analytes on the developed TLC chip. The performance of the stamping method was evaluated on the separation and signal enhancement of an adulterated saffron model matrix (saffron and red 40) as compared to the other two methods (mirror-first and mirror-last methods). The results demonstrated that the mirror-stamping method achieved optimal separation performance with strong SERS signals. This can be attributed to the reduced sample disruption and dilution. Therefore, the mirror-stamping approach demonstrates great potential for use in TLC-SERS analysis to rapidly and accurately determine natural colorant authenticity and quality.