Selective Separation Research Articles

Modelling of a mechanically enhanced PTFE-PVC composite polymer inclusion membrane for highly selective separation of several transition metal ions

Conventional polymer inclusion membranes (PIMs) exhibit suboptimal mechanical properties. Consequently, new composite PIMs were prepared by a modified solvent evaporation method using a PTFE base membrane, a PVC polymer, and an organic phosphonate extractant. Their chemical compositions and microstructures were analyzed by ATR-FTIR and FESEM. The mechanical and mass transfer properties of the composite PIMs were systematically investigated. The composite PIMs exhibited significantly higher tensile strength (36.86 MPa to 52.77 MPa), reduced tensile strain (76.49 % to 118.49 %), and enhanced bursting strength exceeding 0.2 MPa, compared to conventional PIMs. The Zn2+/Cu2+ were separated with a high separation coefficient of 2003.19 by a retardant-enhanced composite PIM system. A new mass transfer model was developed by analyzing the multilayered structure of composite PIMs in depth. The apparent diffusion coefficient of Zn2+ within PTFE-PVC composite layer (7.76 × 10−14 m2/s) was found to be lower than that within polymer inclusion layer (3.18 × 10−13 m2/s). The optimal regions of polymer inclusion layer thickness, contact area, and time were selected by model calculation for a certain separation task (e.g., purity ≥ 0.97 and yield ≥0.80 for Zn2+ or Cu2+). Finally, the retardant-enhanced composite PIMs were successfully used for selective separation of several other transition metal ions.

Preparation of sp2c-COF functionalized silica gel material as chromatographic stationary phases for their high-resolution separation of geometric isomers

Exploration and development of novel chromatographic stationary phases is an effective way to improve the separation efficiency of geometric isomers with similar physicochemical properties. Covalent organic frameworks (COFs) are a new class of porous organic polymers that show a wide range of applications in the field of separation science due to their tunable geometries and functionalities, infinitely extended network structures, and abundant interaction sites. However, the common imine-bonded COFs are poorly resistant to hydrolysis in HPLC. In this work, 2,4,6-trimethyl-1,3,5-triazine (TMT) and 1,3,5-tris (4-formylphenyl) triazine (TFPT) were used as raw materials, a sp2 carbon-conjugated covalent organic framework (sp2c-COF) was synthesized through self-assembly monolayer-assisted surface-initiated Schiff-base-mediated hydroxyl-aldehyde condensation reaction, and loaded on the surface of silica substrate with a CN bond to obtain a new segregated material (SiO2@sp2c-COF). SiO2@sp2c-COF was used as a high-performance liquid chromatography (HPLC) packing material for the separation of geometric isomers. Benefitting from its superb in-plane π-conjugation, highly ordered and robust framework structure, high chemical and thermal stability of sp2c-COF, and the unique hydrophilic covalent triazine groups, hydrophobic benzene rings and other groups that can provide a variety of interactions such as hydrophobicity, π-π stacking, hydrogen bonding and hydrophilicity of the prepared SiO2@sp2c-COF stationary phases, they exhibit excellent molecular shape selectivity and resolution in separating geometrical isomers. These geometric isomers include isomers such as polycyclic aromatic hydrocarbons (PAHs), tocopherols, carotenoids, diethylstilbestrol, 1,4-cyclohexanediol and astaxanthin. Compared to commercial C18 columns, this column has more flexible selectivity and higher separation performance. In addition, due to the introduction of hydrophobicity, π-π stacking action and hydrophilic triazine components, the SiO2@sp2c-COF stationary phase also has RPLC/HILIC mixed mode characteristics. Baseline separations of monosubstituted benzenes, alkylbenzenes, positional isomers, sulfonamides, benzoic acid, anilines, nucleosides and nucleobases compounds were achieved on SiO2@sp2c-COF packed columns. This successful application highlights the great potential of sp2c-COF for the separation of geometrical isomers, and provides a way to overcome the stability of common imine-bonded COFs materials in HPLC, as well as to compensate for the shortcomings and deficiencies of a single chromatographic mode in the separation of complex samples. Furthermore, this is the first report of a practical separation of important geometrical isomers using sp2c-COF materials.

Separation of C6 hydrocarbons on sodium dithionite reduced graphene oxide aerogels

The ability of reduced graphene oxide aerogels (rGOAs) for challenging gas-phase separation was investigated with hexane isomers and benzene (C6 hydrocarbons) using inverse gas chromatography (IGC). For the first, rGOAs were synthesized with sodium dithionite (DTN) as a reductant. Experiments revealed that the most optimal DTN to graphene oxide mass ratio was 2:1, resulting in the highest specific surface area of 432.3 m2 g−1 and the highest degree of graphitization among analyzed samples. C6 hydrocarbon adsorption tests demonstrated the dominant role of the kinetic effect for the adsorption of branched and cyclic hexane isomers - the partition coefficient decreased as the molecule kinetic diameter increased. The contribution of thermodynamic effects was distinguished for molecules with uneven charge distribution. A comparison of the partition coefficient ratios for different pairs of hydrocarbons demonstrated the potential of rGOAs in separating various C6 hydrocarbons. The selectivity, calculated from binary-component adsorption tests of benzene (Bz)/cC6 equimolar mixture, was 13.7, 8.5 and 2.8 for DTN4, DTN2, and DTN1. The research indicates that rGOAs may have potential as adsorbents for the selective separation of hydrocarbons, however, the competitive adsorption and performance at high surface coverages of adsorbates have to be accounted for in further research to assess the applicability of rGOAs reliably.

Peptide retention time prediction for hydrophilic interaction liquid chromatography at acidic pH in formic-acid based eluents

Peptide separation selectivity was evaluated for hydrophilic interaction liquid chromatography (HILIC) ZIC-HILIC, ZIC-cHILIC, and XBridge Amide sorbents using formic acid as eluent additive (pH 2.7). Sequence-specific retention prediction algorithms were trained using retention datasets of ∼30,000 peptides for each column. Our retention models were able to attain ∼0.98 R2-value and yielded retention coefficients that can be probed to understand peptide-stationary phase interaction. Overall, the hydrophilicity for these columns decreased when the mobile phase changed pH from 4.5 to 2.7, when using 0.1 % formic acid in the mobile phase. The acidic residues became protonated, and the resultant hydrophilic interaction is dampened at the lower pH, leaving only the basic residues as the primary hydrophilic interactors. Hence, peptides of increasing charge have higher retention. In this comparison between the three columns, ZIC-HILIC has the highest chromatographic resolution between groups of peptides of different charge. From the position-dependent retention coefficients for ZIC-HILIC at pH 2.7, we found that the amino acids at the terminal positions of the peptide modulate the basicity of the N-terminal amino group or the C-terminal Arg/Lys for tryptic peptides. With respect to the separation orthogonality between HILIC and acidic pH RPLC for two dimensional separations, the orthogonality values were lower at pH 2.7 than operating HILIC at pH 4.5 for the first dimension. We also demonstrate that ZIC-HILIC was able to distinguish citrullinated and deamidated peptides based on predicted retention values.

Alkaline-resistant covalent organic framework membranes for selective hydroxide ion separation

Alkali holds a pivotal role in the chemical industry, however, the substantial discharge of alkaline wastewater causes a severe waste of resources and environmental pollution. Conventional polymer membranes have ether bonded backbones and form randomly assembled nanochannels, suffering from a weak alkali resistance and a low hydroxide ion selectivity. Covalent organic frameworks (COFs), known for their robust framework structure, highly ordered channels, and tunable channel chemistry, have been considered as the competent candidate for alkaline-resistant membranes for selective hydroxide ion separation. Herein, we fabricate a β-ketoenamine COF (TpTAPB) membrane with a high alkaline resistance via the interfacial growth strategy. After post-sulfonation, the negatively charged channels of sulfonated TpTAPB membrane allows OH- with smaller size and lower charges to pass through while repulsing WO42- ions, achieving a selectivity of OH-/WO42- up to ∼ 60 and surpassing commercial and most reported polymeric membranes. This work expands the application scope of COF membranes in selective alkali separation.

Redox-active sp2-c connected metal covalent organic frameworks for selective detection and reductive separation of uranium

It is economically desirable to develop a material that can simultaneously detect and recover uranium. Herein, a CC-bridged two-dimensional metal-covalent organic framework (Cu-BTAN-AO MCOF) was constructed by condensation of metal single crystals with a rigid structure (Cu3(PyCA)3) and cyano monomers (BTAN) via Knoevenagel reaction for simultaneous detection and adsorption of uranium. The amidoxime group within the pore and the presence of unsaturated Cu(I) in the framework facilitate the adsorption of uranyl ions onto the amidoxime group, leading to fluorescence quenching via the photoinduced electron transfer (PET) mechanism, achieving a detection limit of as low as 167 nM uranyl ions. Furthermore, Cu-BTAN-AO demonstrates exceptional efficiency in capturing uranium from wastewater characterized by rapid kinetics and superior selectivity. It is noteworthy that Cu-BTAN-AO is the first example of simultaneous detection, adsorption and chemical reduction of uranium using metal centers and functional groups in MCOF, indicating that Cu-BTAN-AO has great potential for the detection and recovery of uranium-containing wastewater. This design strategy may also be applicable to advancing sensing and energy materials for other important metal ions.

Antisolvent crystallization of rare earth sulfate hydrates: Thermodynamics, kinetics and impact of iron

The thermodynamics and kinetics of ethanol antisolvent crystallization of rare earths from sulfate solutions has been explored, with a view towards separating the rare earths as part of a NdFeB magnet recycling process. The solubility of single and binary metal (Nd, Pr, Fe) phases in aqueous ethanol solutions has been determined. The impact of Fe and Pr on the crystallization of Nd is evaluated, the oxidation kinetics of Fe(II) to Fe(III) quantified, and the influence of Fe oxidation state on the thermodynamics and kinetics of crystallization investigated. Oxidation to Fe(III) is slow, with a half life of approx. 600 h. For pure Nd, the solubility of the obtained, stable sulphate octahydrate decreases exponentially with increased molar organic:aqueous (O/A) ratio, and is well described by the OLI model until O/A=0.2. Pr crystallizes as an isostructural octahydrate with similar solubility. Fe(II) precipitates as a mixed solid phase, with a solubility approximately 40 times higher than the rare earths at O/A=0.2. Fe(III) solutions exhibit liquid–liquid phase separation without precipitation at all evaluated concentrations. Nd and Pr coprecipitate together in proportion to their relative concentrations, with Pr precipitating at concentrations well below its pure component solubility. Fe(II) does not precipitate with Nd at O/A≤0.2 even at high concentration, with significant precipitation as separate particles at higher O/A for all concentrations. The crystallization kinetics and the morphology of the Nd phase is affected by the Fe oxidation state. The work highlights the potential of antisolvent crystallization for selective and efficient separation of REE from Fe.

Use of Near-to-Microporous Silica Gel for Selective Separation of Petroleum Vanadyl Porphyrins from Asphaltene Clusters

Use of Near-to-Microporous Silica Gel for Selective Separation of Petroleum Vanadyl Porphyrins from Asphaltene Clusters

High-Performance Crown Ether-Modified Membranes for Selective Lithium Recovery from High Na+ and Mg2+ Brines Using Electrodialysis

The challenge of efficiently extracting Li+ from brines with high Na+ or Mg2+ concentrations has led to extensive research on developing highly selective separation membranes for electrodialysis. Various studies have demonstrated that nanofiltration membranes or adsorbents modified with crown ethers (CEs) such as 2-OH-12-crown-4-ether (12CE), 2-OH-18-crown-6-ether (18CE), and 2-OH-15-crown-5-ether (15CE) show selectivity for Li+ in brines. This study aims to develop high-performance cation exchange membranes (CEMs) using CEs to enhance Li+ selectivity and to compare the performance of various CE-modified membranes for selective electrodialysis. The novel CEM (CR671) was modified with 12CE, 18CE, and 15CE to identify the optimal CE for efficient Li+ recovery during brine electrodialysis. The modification process included polydopamine (PDA) treatment and the deposition of polyethyleneimine (PEI) complexes with the different CEs via hydrogen bonding. Interfacial polymerization with 1,3,5-benzenetricarbonyl trichloride-crosslinked PEI was used to create specific channels for Li+ transport within the modified membranes (12CE/CR671, 15CE/CR671, and 18CE/CR671). The successful application of CE coatings and Li+ selectivity of the modified membranes were verified through Fourier-transform infrared spectroscopy, zeta-potential measurements, and electrochemical impedance spectroscopy. Bench-scale electrodialysis tests showed significant improvements in permselectivity and Li+ flux for all three modified membranes. In brines with high Na+ and Mg2+ concentrations, the 15CE/CR671 membrane demonstrated more significant improvements in permselectivity compared to the 12CE/CR671 (3.3-fold and 1.7-fold) and the 18CE/CR671 (2.4-fold and 2.6-fold) membranes at current densities of 2.3 mA/cm2 and 2.2 mA/cm2, respectively. At higher current densities of 14.7 mA/cm2 in Mg2+-rich brine and 15.9 mA/cm2 in Na+-rich brine, the 15CE/CR671 membrane showed greater improvements in Li+ flux, approximately 2.1-fold and 2.3-fold, and 3.2-fold and 3.4-fold compared to the 12CE/CR671 and 18CE/CR671 membranes. This study underscores the superior performance of 15CE-modified membranes for efficient Li+ recovery with low energy demand and offers valuable insights for advancing electrodialysis processes in challenging brine environments.

Reverse cationic flotation of low-grade phosphate ore using quaternary ammonium salt as a collector and its adsorption mechanism

A novel quaternary ammonium salt collector, LH-01, was employed for the reverse cationic flotation of a magnesium-depleted concentrate (P2O5 grade of 19.72wt%, SiO2 content of 44.26wt%). We achieved an outstanding phosphate concentrate with a P2O5 grade of 35.16wt%, a SiO2 content of 6.06wt%, and a P2O5 recovery of 75.88%. This process was accomplished through two sequential reverse cationic flotation processes designed for quartz removal. Importantly, the quartz removal by LH-01 reached 94.17%, far superior to that by dodecyltrimethylammonium chloride, achieving highly selective separation of quartz and apatite. To understand the adsorption mechanism and kinetics of the collector LH-01 on quartz and apatite surfaces, various techniques, such as quartz crystal microbalance with dissipation, atomic force microscopy, and X-ray photoelectron spectroscopy, were employed. Results revealed that the adsorption layer of LH-01 on the apatite surface was thin and rigid, with a significantly lower hydrophobic effect than that of the viscoelastic multiple adsorption layer formed by LH-01 on the quartz surface. This disparity was identified as the primary factor contributing to the selective flotation separation of apatite and quartz. Moreover, the adsorption of LH-01 on the quartz surface was the result of multiple forces, including electrostatic adsorption, multiple-hydrogen-bond adsorption, and intermolecular hydrophobic association.

Cyphos Nitrate Selectively Separates Y(III) from Sr(II) Present in Acidic Feed Solution: An Efficient Ionic Liquid based Extraction Process

AbstractMutual separation of Y(III) and Sr(II) from their waste solution has been an emerging research domain due to their various industrial applications. In this investigation, we emphasize the feasibility of selective separation of Y(III) from Sr(II) present in nitric acid medium using undiluted cyphos nitrate ionic liquid (IL): trihexyl(tetradecyl)phosphonium nitrate ([P66614][NO3]) as the ligating phase. The set experimental parameters were the feed phase acidity, initial nitrate ion concentration, initial feed metal ion concentration, equilibration time and temperature to unveil the efficacy of the proposed system. Efficient extraction of Y(III) selectively in presence of Sr(II) using only a salting agent in aqueous phase without additional extractant in IL phase was highlighted. A remarkable separation factor (SF) obtained for Y(III) over Sr(II) explored the efficacy of the proposed IL system. Y(III) loading in IL phase both in unirradiated and irradiated conditions was compared to evaluate the coordination behavior of irradiated moieties. In addition, a most important advantage of the proposed system is that it employs Milli‐Q water for the back extraction (stripping) of the loaded Y(III) from IL phase and does not demand any complexing agent (water soluble). This undoubtedly corroborates the economic and environmental benefits of the proposed IL system.

Enhancing CO2/CH4 separation performance in PIM-1 based MXene nanosheets mixed matrix membranes

This study presents an approach by integrating MXene nanosheets (Ti2C3Tx) into polymer of intrinsic microporosity (PIM-1) matrix to develop mixed matrix membranes (MMMs) for biogas upgrading. Different concentrations (1–5 wt%) of MXene were incorporated into PIM-1, and the resulting materials were characterized to 1H NMR, FTIR, XRD, TGA, nitrogen adsorption, SEM and EDS to assess their physicochemical properties. The research focused on evaluating the gas separation performance, particularly CO2/CH4 separation, as well as the aging behavior of the MMMs. The incorporating of MXene nanosheets significantly enhanced the CO2 permeability and selectivity of PIM-1 by enhancing gas solubility and diffusivity. The most promising results were observed at 5 wt% filler loading, achieving a 13.5 CO2/CH4 separation selectivity at 7652 Barrer of CO2 permeability. In all membranes with aging time (60 days), there was a decrease in CO2 permeability and a slight increase in CO2/CH4 selectivity, observing that the introduction of MXene slightly mitigates the physical aging process in the PIM-1 polymer. Additionally, the permeability tests revealed higher CO2 permeability and (CO2/CH4) selectivity values for mixed gases compared to single gases. Overall, the study highlights the potential of MXene/PIM-1 MMMs as effective materials for CO2/CH4 separation, outperforming pristine PIM-1.

Highly selective alginate/CuO mixed matrix membranes for efficient dehydration pervaporation of various organic solvents

Pervaporation is an energy-efficient technique for dehydrating organic solvents from aqueous mixtures. To develop a highly selective pervaporation membrane with broad usage, we incorporated three types of CuO particles (solid CuO-S, sea urchin-like CuO-U, and porous CuO-P) into sodium alginate (Alg) for fabricating the Alg/CuO mixed matrix membranes (MMMs). The CuO syntheses and membrane preparation are simple and eco-friendly. The synthesized particles and membranes were systematically characterized. The improved hydrophilic feature of Alg/CuO MMMs was validated from the reduced water contact angle and higher water swelling ratio with increasing CuO wt%. When the Alg/CuO MMMs were applied to the pervaporation of 30 wt% water/isopropanol (IPA) at 25 ℃, both the permeation flux and separation factor were enhanced significantly compared to the pure Alg membrane. The separation efficiency followed the order of Alg/CuO-S MMMs < Alg/CuO-U MMMs < Alg/CuO-P MMMs, in good agreement with their water swelling tendency. The incorporation of 3 wt% porous CuO-P particles in MMM achieved the optimal dehydration efficacy (normalized total flux of 3.5 kg m-2h−1, separation factor of ca. 5000, and water purity of 99.96 wt%, with a stable performance over 168 h). A further larger loading wt% led to a decreased separation selectivity due to more void formation from particle aggregation. With an increase in feed temperature, both the permeation flux and separation factor were improved; however, the increase in feed water concentration deteriorated the separation selectivity while enhancing the flux. Furthermore, the high selectivity and broad applicability of Alg/3% CuO-P MMM were fruitfully demonstrated by exhibiting superior separation efficiencies in dehydrating various polar aprotic solvents compared with several membranes discussed in the literature.

Stable hierarchical ionic liquid nanochannels for highly efficient CO2 adsorption, separation and conversion

Constructing stable nanochannels and nanoconfined environments for ionic liquids holds significant application value in gas separation, ion channels, and related fields. The functional polyionic liquid synthesized in this study exhibits a controllable assembly structure and demonstrates liquid crystal properties. Through heating and water treatment, the polyionic liquids crosslink to form multi-hierarchical nanopores, including sub-nanochannels with pore sizes similar to CO2, without the need for a catalyst. The specific surface area and pore size of the polyionic liquid network (PILC) were adjusted by regulating the self-assembly of polyionic liquids in water. The unique PILC, combining ionic liquid nanopores and liquid crystal structure properties, shows high CO2 adsorption performance and excellent CO2/N2 selectivities, surpassing commonly reported ionic liquid porous materials. Furthermore, PILC-2 exhibits good catalytic performance for CO2 cycloaddition, and its catalytic activity and selectivity did not significantly decrease after five cycles. This study successfully introduces hierarchical ionic liquid nanochannels into porous networks without involving any inorganic ordered nanomaterials. This provides a simple and effective approach for the highly selective adsorption and separation of CO2, as well as for the preparation of catalytic materials.

Phase Separation Manipulated Gradient Conductivity for A High‐Precision Flexible Pressure Sensor

AbstractPiezoresistive pressure sensors, analyzing and converting external pressure signals to readable electrical signals for monitoring human health, are always subjected to simultaneously possess high signal‐linearity and signal sensitivity. Analogous to the control of sophisticated microstructure for increasing active sensing area, the control of gradient conductivity should enable a linear response via regulating the formed saturation current. Here, inspired by phase separation showing the feasibility of controlling material microstructure and conductivity, a high‐performance flexible pressure sensor via the simultaneous control of microgroove structure and wide‐range gradient conductivity is demonstrated. First, a laser‐etching and dopamine (DA)‐doping synergistic approach is used to induce selective phase separation in poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS), achieving broad conductivity modulation (from 297 to 4525 S cm−1) and precise microgroove pattern (15.5 µm). Then, by designing conductivity‐gradient PEDOT: PSS‐based multi‐sublayers and microgroove interlocked structure, the sensor shows extraordinarily comprehensive performance of excellent stress‐sensing sensitivity (4 × 105 kPa−1), high linear responsiveness (99.85%) and wide‐range sensing ability (up to 100 kPa). Consequently, this sensor reveals excellent capability in detecting multi‐mode pressure changes and is expected to branch out into other electronic device designs as a general strategy for the precise manipulation of material physical‐chemical properties.

On-line enrichment and separation of glycoprotein by capillary electrophoresis based on pH response coating column

A capillary column coated with 3-aminophenylboronic acid (APBA)-functionalized gold nanoparticles (AuNPs@APBA) was prepared via electrostatic self-assembly. The coated column exhibited anti-nonspecific adsorption of glycoproteins, enabling selective online enrichment during capillary electrophoresis (CE). First, gold nanoparticles (AuNPs) were synthesized using the sodium citrate reduction method. Then, APBA was self-assembled electrostatically on the surface of the AuNPs to obtain AuNPs@APBA. This nanomaterial was bonded to the inner wall of a capillary through ion adsorption to produce a AuNPs@APBA-coated capillary column. Glycoproteins were adsorbed via bond formation with boric acid groups under alkaline conditions (pH 8) to generate borate esters. Under acidic conditions (pH 3), the borate esters dissociated to release the glycoproteins, thereby achieving the selective online enrichment and separation of glycoproteins. The AuNPs and AuNPs@APBA were characterized using Fourier transform infrared spectroscopy, and their sizes and Zeta potentials were determined. In addition, the electroosmotic flow (EOF) of the AuNPs@APBA-coated capillary column was measured. The results showed that the surface of the AuNPs was successfully modified with APBA and that AuNPs@APBA was adsorbed on the inner wall of the capillary. The peak area of ovalbumin (OVA) on the AuNPs@APBA-coated column was 26.46 times higher than that on a bare column via conventional electrophoresis. In contrast, the peak area of bovine serum albumin (BSA) only increased by 8.47 times, indicating that the AuNPs@APBA coated column selectively enriched glycoproteins. Evaluation of the reproducibility and stability of this method revealed that the AuNPs@APBA coated capillary column could be used continually for 33-67 h. The relative standard deviations (RSDs) of the peak areas for intra-day (n=5) and inter-day (n=6) analyses were 2.2% and 3.0%, respectively. The developed method was successfully applied to enrich glycoproteins in a 1×106-fold diluted egg white sample. Glycoproteins were not detected using conventional electrophoresis on the bare column, whereas the AuNPs@APBA-coated capillary column effectively enriched and separated glycoproteins, resulting in a peak area of 10469 mAU·ms. Furthermore, the entire enrichment and separation process was completed within 3 min. This new online enrichment and separation method for glycoproteins has the advantages of low sample consumption, simple operation, and high separation efficiency.

Advances and challenges in the fractionation of edible oils and fats through supercritical fluid processing.

Petrochemical solvents are widely used for the extraction and fractionation of biomolecules from edible oils and fats at an industrial scale. However, owing to its safety concerns, toxicity, price fluctuations, and sustainability, alternative solvents and technologies have been actively explored in recent years. Technologies, such as ultrasound and microwave-assisted extraction, supercritical carbon dioxide extraction, supercritical fluid fractionation, and sub-critical water extraction, and solvents, like ionic liquids and deep eutectic solvents, are reported for extraction and fractionation of biomolecules. Among them, supercritical carbon dioxide extraction and fractionation are some of the most promising green technologies with the potential to replace petrochemical-based conventional techniques. The addition of cosolvents, such as water, ethanol, and acetone, improves the extraction of amphiphilic and polar compounds from edible oils and fats. Supercritical fluid processing has diverse applications, including concentration of solutes, selective separation of desired molecules, and separation of undesirable compounds from the feed material. Temperature, pressure, particle size, porosity, flow rate, solvent-to-feed ratio, density, viscosity, diffusivity, solubility, partition coefficient, and separation factor are the fundamental factors governing the extraction and fractionation of desired biomolecules from lipids. Supercritical fluids stand alone compared to conventional fluids, because of their tunable solvent properties. Overall, it is to be noted that supercritical fluid-based methods have lots of scope to replace conventional solvent-based methods and progress toward the creation of sustainable food-processing techniques. This review critically evaluates the parameters responsible for the extraction and fractionation of biomolecules from edible oils and fats under supercritical conditions.

Development of cost-effective cellulose-based bilayer hybrid composite membranes for CO2 separation in biogas purification.

CO2 is the main pollutant in biogas, reducing its calorific value. Among various technological methods to eliminate carbon dioxide from biogas, membrane separation technology stands out for large-scale industrial biogas purification due to its advantages. The selection of membrane material and preparation process are key factors in membrane separation technology. In this study, a premixing process was initially used to blend different masses of packed molecular sieves TS-1 (or ZSM-5) and cellulose derivatives (ethyl cellulose, cellulose acetate) separately. These mixtures were then coated onto porous PVDF substrates using a coating process to create various bilayer hybrid composite membranes. Among these, PVDF/EC-ZSM-5 (containing 15% ZSM-5) bilayer hybrid composite membrane is the most fitting. For CO2/CH4 gas mixtures, the gas selectivity of this membrane surpassed Robeson's 1991 standard line (the CO2 permeability was 597.48 Barrer, and the CO2/CH4 selectivity was 9.14). Overall, this composite membrane, made for the first time from PVDF, ZSM-5, and EC, is expected to be a promising CO2 selective separation membrane material for biogas purification in large-scale industrial processes due to its simple production process.

Low swelling and high mechanical strength organosilane hybrid polydivinylbenzene microspheres for hydrophilic interaction chromatography applications.

In this work, monodisperse organosilane hybrid polymer microspheres with a particle size of about 5µm were synthesized using seed swelling polymerization. The organosilicon reagent methacryloxypropyltrimethoxysilane was introduced into the polymer framework as a copolymerization monomer, and the crosslinking degree of the microspheres was improved by the hydrolysis-condensation reaction of siloxanes. The synthesized hybrid microspheres have good mechanical strength as well as low swelling, with swelling propensity values of 0.167 and 0.348 in methanol and acetonitrile, respectively. Hybrid microspheres modified with cysteine have a hydrophilic interaction chromatography/reversed-phase liquid chromatography mixed-mode retention mechanism. Compared to the commercial cysteine-modified silica column, the synthesized stationary phase has higher separation selectivity for partially acidic or basic samples and better basic resistance for use under high pH mobile phase conditions (at least 10).

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.