Selective Separation Research Articles

Simultaneous removal of CTRX and Cr(Ⅵ) by CQDs-doped bifunctional molecular imprinted BiOCl/Bi3NbO7 photocatalyst: The enhanced selective performance and charge separation abilities

As a commonly used additive in breeding industry, the complex pollutants and metabolites formed by antibiotics and heavy metals in aquaculture wastewater have the characteristics of strong persistence, refractory degradation and easy accumulation, and exist in the environment and human body for a long time, which caused seriously ecological, environmental and health problems. Their effective removal studies are very essential. In this paper, a CQDs-doped bifunctional molecular imprinted BiOCl/Bi3NbO7 heterojunction photocatalyst (CQDs-MIP-BNO) was fabricated and the micromorphology along with photoelectric characteristics were explored by SEM, XRD, FTIR, XPS, UV-Vis and PL analysis. The photocatalytic performance experiments implied that 10 % doping of CQDs showed the highest selectivity and photocatalytic activity for the 94 % removal rate of Ceftriaxone Sodium (CTRX) and 80 % of Cr (VI) within 45 min. On this basis, a photocatalytic reactor loaded with the as-synthesized bifunctional catalyst through a sponge mesh covered with CS/PVA film was set up and the actual operation potential was further explored. The results showed that the enhanced removal performance of this bifunctional photocatalyst for CTRX and Cr(VI) made it feasible to efficiently remove one or more low-concentration, high-toxicity antibiotics and heavy-metal pollutants from the water column to validate the utility of combining molecular imprinting and photocatalytic technologies for the treatment of aquaculture wastewater.

Enhancing chloride/fluoride selectivity with hydrophobic side-chain anion exchange membranes in electrodialysis

The selective separation of chloride ions (Cl−) from fluoride ions (F−) is a critical concern in various industries due to the potential risks of F− on public health and industrial operations. However, Cl−/F− separation is known to be technologically challenging, considering they have the same charge and valency. This study explores the design of anion exchange membranes (AEMs) in electrodialysis to achieve Cl−/F− separation based on the difference in their hydration energy. Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) polymers brominated at varying reaction temperatures were employed as the basic AEM material, enabling fine-tuning of the hydrophobic properties of the resulting membranes through selective bromination at the benzyl or aryl positions and the subsequent quaternization with tertiary amines of different chain lengths, ultimately enhancing their selectivity. The developed AEMs are tested in electrodialysis involving a binary Cl−/F− mixture. The obtained membranes exhibited remarkable selectivity, reaching as high as 12.5 ± 1.0, surpassing the performance of commercial monovalent selective AEMs. The results demonstrate the potential of Cl−/F− separation by electrodialysis and highlight the significance of tailored membrane design in achieving the separation of ions with the same valency.

Synthesis, application and molecular docking of modified cellulose with diaminoguanidine as complexing agent for selective separation of Cu (II), Cd (II) and Hg (II) ions from alum sample

A new modified cellulose with diaminoguanidine (Cel-Gua) synthesized for specific recovery of Cu (II), Cd (II), and Hg (II) from the alum sample. Cellulose was silanized by 3-chloropropyltrimethoxysilane and then was modified with diaminoguanidine to obtain N-donor chelating fibers. Fourier transform-infrared spectroscopy, scanning electron microscopy, X-ray diffraction, zeta potential, electrons disperse X-ray analysis, elemental analyses (C, H and N), and thermogravimetric analysis were used for characterization. Factors influencing the adsorption were thoroughly examined. Under the optimal conditions, the Cel-Gua sorbent displayed maximum adsorption capacities of 94.33, 112.10 and 95.78 mg/g for Cu (II), Cd (II), and Hg (II), respectively. The sorption process of metal ions is equipped by kinetic model PSO and Langmuir adsorption isotherm. The calculated thermodynamic variables confirmed that the adsorption of Cu (II), Cd (II) and Hg (II) by Cel-Gua sorbent is a spontaneous and exothermic process. In our study, we used the molecular operating environment software to conduct molecular docking simulations on the Cel-Gua compound. The results of the docking simulations showed that the Cel-Gua compound displayed greater potency and a stronger affinity for the Avr2 effector protein derived from Fusarium oxysporum, a fungal plant pathogen (code 5OD4). The adsorbent was stable for 7 cycles, thus allowing its safe reutilization.

Selective mono/divalent ion separation in bifunctional ionomeric capacitive deionization incorporated with counter-charge ionomer layer

In this study, a carbon-based bifunctional ionomeric capacitive deionization (BICDI) system was successfully developed by applying a counter-charge ionomer layer to the BICDI electrode without the need of a monovalent ion exchange membrane (M-IEM) for the selective separation of mono/divalent ions. The counter-charge ionomer layer facilitates the selective separation of mono/divalent ions through a combination of mechanisms involving electrostatic repulsion, steric hindrance, and hydrophobic interactions. Meanwhile, the BICDI electrode matrix serves as an ion transport channel, enabling seamless ion transport and improving the electrosorption capacity of the electrode. SEM and EDS analyses have confirmed the presence of a counter-charge ionomer layer encapsulating the BICDI electrode. Notably, BICDI-C cell with counter-charge ionomer layer exhibits higher Li+ ion adsorption capacity and selectivity (321.6 μmol/g, βMg2+Li+=6.6) compared to commercial monovalent cation exchange membrane CDI (MCDI-C) cell (206.4 μmol/g, βMg2+Li+=1.4). The selectivity of the BICDI-C cell for mono/divalent ions can be optimized by adjusting various testing parameters, including flow rate, voltage, etc. More importantly, this versatile method is not only applicable for the separation of monovalent cation, but can also enhance the monovalent anion adsorption capacity and selectivity of BICDI-A (43.6 μmol/g, βSO42-Cl-=7.3) cell by incorporating a counter-charge ionomer layer onto the BICDI cathode. This approach allows for the efficient separation of both cationic and anionic species, broadening the range of potential applications for BICDI technology.

Significant promotion of NO separation selectivity from flue gas by the –NH2 functional group on Fe–Ni bimetallic MOF at ambient conditions

Significant promotion of NO separation selectivity from flue gas by the –NH2 functional group on Fe–Ni bimetallic MOF at ambient conditions

The retention features of nitrogen-containing heterocyclic compounds in reversed-phase and hydrophilic HPLC-MS modes

Aromatic five- and six-membered nitrogen-containing heterocyclic compounds are biologically active substances and are widely used in biochemistry and medicine. In addition, such compounds are known as ecotoxicants formed during oxidation processes in industrial wastewater. High-performance liquid chromatography-mass spectrometry is widely used to determine nitrogen-containing heterocycles in various complex mixtures. Octadecyl silica gel is the main sorbent for chromatographic separation. However, octadecyl silica gel does not always enable satisfactory separation in the presence of highly polar isomeric molecules, and more selective chromatographic approaches are required. One of these is hydrophilic chromatography, which facilitates the separation of polar compounds. The aim of the study was to comparatively characterize the retention of a number of five- and six-membered nitrogen-containing heterocyclic compounds during reversed-phase and hydrophilic liquid chromatography with mass spectrometric detection. In addition, spectrophotometric detection at a wavelength of 210 nm was carried out. In the study, we used sorbents based on octadecyl silica gel and unmodified silica gel. High-resolution mass spectrometry was used in the electrospray ionization mode. We studied 19 nitrogen-containing heterocyclic compounds. We used aqueous acetonitrile mobile phases with added aqueous solutions of formic acid and diethylamine as acid-base modifiers. An ammonium formate solution was used as a modifier during hydrophilic chromatography. Reversed-phase chromatography showed that the introduction of 0.1% aqueous formic acid solution increased the ionization and the mass spectrometer signal intensity, but did not always result in a satisfactory separation of isomers upon elution from the octadecyl silica gel surface. The introduction of 0.01% diethylamine solution provided no significant improvement in the separation compared to the mobile phase without modifiers. The use of unmodified silica gel in hydrophilic chromatography mode allowed us to separate isomeric five-membered heterocycles, which was demonstrated by narrow symmetric peaks, but did not result in selective separation of isomeric diazines. Thus, we studied the retention of 19 nitrogen-containing heterocyclic compounds using reversed-phase and hydrophilic liquid chromatography with electrospray ionisation. It was determined that hydrophilic chromatography on unmodified silica gel could be used for satisfactory separation of isomeric five-membered heterocyclic compounds of different classes. For six-membered heterocycles, satisfactory separation was achieved by elution from the surface of octadecyl silica gel using aqueous acetonitrile mobile phase without modifiers.

Preparation of Free-Standing Defect-Free ZIF-8/PVA Membranes via Confined Reaction at the Quasi-Interface.

Developing a facile strategy to synthesize free-standing defect-free metal-organic framework (MOF) membranes with high separation selectivity and good mechanical stability is very appealing but challenging. Herein, by confining the reaction of metal and ligand at the quasi-interface, a representative membrane composed of a continuous ZIF-8 layer and poly(vinyl alcohol) (PVA) was fabricated. The continuous ZIF-8 layer endowed the membrane with high separation efficiency, while PVA acted as a filler to eliminate the defection, synergistically achieving high selective ion transport and good mechanical stability. The continuous defect-free ZIF-8/PVA membrane showed excellent separation performance of selective ion transport with high Li+ permeance of 17.83 mol·m-2·h-1 as well as decent Li+/Mg2+ and Li+/Ca2+ selectivities of 24.60 and 244.58, respectively. The separation performance of the ZIF-8/PVA membrane remained stable after 10% strain, indicating its good mechanical stability. This work will promote the development of MOF-based membranes in practical applications.

Substituent effects of Phenanthroline-Derived Phosphine-Oxide extractants on extraction and separation performance towards U(VI)/Th(IV)

Designing and selecting extractants with high selectivity between uranium and thorium, and developing the relevant separation process is one of the key points to realize efficient utilization of nuclear resources in the thorium-uranium nuclear fuel cycle. In this work, we used four phenanthroline-derived phosphine-oxide extractants with different substituents and studied their extraction ability and separation effect on U(VI)/Th(IV) under different conditions. The Et2-BPPhen and Ph2-BPPhen extractants show weak and strong extraction abilities for U(VI) and Th(IV), respectively. The Et-Ph-BPPhen(R,R) and Et-Ph-BPPhen(R,S) extractants could co-extract U(VI) and Th(IV) under high acidity (DU(VI) > 300, DTh(IV) > 40, SFU(VI)/ Th(IV) < 7, 4 M HNO3), and show high selectivity towards U(VI) over Th(IV) at low acidity (SFU(VI)/ Th(IV) > 200, 0.1 M HNO3). Most Th(IV) can be stripped by adjusting the acidity of the aqueous phase, while U(VI) still remains in the organic phase (STh(IV) ＞ 95 %, SU(VI) < 5 %), so as to achieve the step-by-step process for co-extraction and selective separation. Then, the slope analysis and NMR titration (1H and 31P) determined BPPhen ligands could form ML-type complex with U(VI), and can simultaneously form M/L = 1:1 and 1:2 complexes with Th(IV). The stability constants of the metal–ligand complexes were fitted by UV–Vis spectroscopic titration to estimate coordination abilities of four ligands. Finally, the single-crystals of complexes with the structures of [UO2(L)(NO3)2], [Th(L)(NO3)4] and [Th(L)(H2O)2]·4(ClO4), (L = Et2-BPPhen/Et-Ph-BPPhen(R,R)/Et-Ph-BPPhen(R,S)/Ph2-BPPhen) were produced, and their coordination and packing mode were analyzed. This work contributes to revealing the structure–activity relationship of phenanthroline phosphine-oxide extractants and providing a reference for designing new extractants with high U(VI)/Th(IV) separation efficiency.

Suitable Pore Confinement with Multiple Interactions in a Low-Cost Zeolitic Imidazolate Framework for Efficient Xe Capture and Separation

The increasing industrial demand for the noble gases xenon (Xe) and krypton (Kr), along with growing environmental concerns on their radionuclides, has made the efficient separation and purification of Xe and Kr a critical issue. Leveraging advanced porous materials to achieve highly efficient adsorptive Xe/Kr separation has been recognized as an energy-saving and economical alternative to the widely used cryogenic distillation technology. Herein, we present a stable, low-cost, and easily scalable zeolitic imidazolate framework (ZIF) material, ZIF-4, for effective xenon adsorption and separation. ZIF-4 possesses uniformly distributed pore cavities with ideally matched pore size (4.3 Å) with that of Xe atom (4.047 Å), providing appropriate pore confinement for Xe binding. Sorption isotherms of ZIF-4 demonstrate the remarkably high Xe uptake (1.64 mmol/g at 0.2 bar and 298 K) and excellent Xe/Kr separation selectivity (16.2 for IAST selectivity of 20/80 Xe/Kr gas mixtures). Breakthrough experiments further validate the efficient separation performance of ZIF-4 in both binary Xe/Kr (20/80) gas mixtures and under dilute conditions. Single-crystal X-ray diffraction studies of activated and Xe-loaded ZIF-4 crystals reveal that the flexible pore cavities of ZIF-4 can self-adaptively adsorb and accommodate Xe atoms through the rotation of imidazolate rings, forming multiple Xe···H and Xe···π interactions to create strong binding sites for Xe capture and discrimination. The stability, economic feasibility, and scalability of ZIF-4 underscore its significant potential for industrial Xe/Kr separation.

Selective Separation of Lithium from Leachate of Spent Lithium-Ion Batteries by Zirconium Phosphate/Polyacrylonitrile Composite: Leaching and Sorption Behavior

This study introduces a straightforward and effective amorphous ZrP/polyacrylonitrile composite ion exchange method for separating Li from the leachate of spent Li-ion batteries (NMC 111). The cathode materials were leached with a series of optimized experiments. The influence of operating variables, including the H2SO4 concentration, temperature, H2O2 concentration, and pulp density, on leaching efficiency was examined to determine the optimal conditions for sorption experiments. The leaching efficiencies of Li, Co, Ni, and Mn were found to be 99.9%, 99.5%, 98.8%, and 99.9%, respectively. Subsequently, batch sorption experiments were performed by using am-ZrP/PAN, including the determination of the effect of pH, sorption kinetics, and the sorption isotherm. The effect of pH on adsorption was examined in 1 mmol/L equimolar solutions of Li, Ni, Mn, and Co. Li was separated from Mn, Co, and Ni in the leaching liquor. The adsorbent for Mn, Co, and Ni sorption better fitted pseudo-second-order kinetics. High selectivity for Li was observed, even at the higher solution concentration of 15 mM Li, Ni, Co and Mn. In addition, the column loading process demonstrated selectivity for Li over Co, Ni, and Mn metal ions. The preliminary evaluation of the whole process with mass flow demonstrated that it would be feasible to achieve full separation and metal recovery by integrating a combined hydrometallurgical method in future studies. However, much work is still needed to develop a practical separation flowsheet.

Tailored Postsynthetic Nitration of a Hypercrosslinked Polymer for Single-Step Ethylene Purification from a Ternary C2 Gas Mixture.

Purifying C2H4 from a ternary C2H2/C2H4/C2H6 mixture poses a substantial industrial challenge due to their close physical and chemical properties. In this study, we introduce an innovative design approach to regulate and optimize the nitration degree of a hypercrosslinked polymer to achieve targeted separation performance. We synthesized a porous organic polymer (HCP) using the solvent knitting method and carried out its postsynthetic nitration, resulting in HCP-NO2-1 and HCP-NO2-2 with different nitration degrees. Notably, the adsorption capacity shifted from C2H6 > C2H4 ≈ C2H2 for HCP to C2H2 > C2H6 > C2H4 for HCP-NO2-1 and to C2H2 > C2H4 ≈ C2H6 for HCP-NO2-2, demonstrating the controllable nature of the separation process via the polar nitro group insertion. Remarkably, HCP-NO2-1 exhibited a desirable, selective separation of C2H4 from the C2H6/C2H4/C2H2 mixture thanks to an exquisite combination of the acidic proton-polar nitro group and nonpolar C-H∙∙∙π interactions. Separation capability was further corroborated by computational simulations and breakthrough tests. This work marks a significant advancement as the first successful postsynthetic functionalization strategy for C2H4 purification from a ternary gas mixture among porous organic polymers.

Innovating an amphoteric collector derived from dodecylamine molecular structure: Facilitating the selective flotation separation of apatite from quartz and dolomite

This paper introduces a novel amphoteric collector, N-dodecyl-β-alanine (DDALA), derived from the molecular structure of dodecylamine, with the incorporation of a propionic acid group. In the study, flotation experiments are undertaken to examine the selectivity of DDALA in apatite flotation. Results demonstrate that DDALA, in combination with xanthan gum (XG) depressant and oleic acid collector successfully accomplishes the reverse flotation separation of apatite from quartz and dolomite. In addition, the synergistic application of zeta potential experiments, X-ray photoelectron spectroscopic tests, and first-principles calculations has been employed to delve into the action mechanisms of DDALA collector and XG depressant. By combining the results with existing research, the paper proposes that the selective adsorption of XG between apatite and quartz surfaces facilitates the selective separation of these two minerals by DDALA collector. Moreover, the intermediate collecting ability of DDALA/oleic acid combined collector for dolomite results from the competitive adsorption of DDALA neutral molecules and oleic acid anions on dolomite surface. Furthermore, the formation of hydrophilic molecular aggregates between DDALA neutral molecules and oleic acid anions on apatite surface diminishes the collecting ability of DDALA/oleic acid combined collector for apatite compared to the individual use of each collector.

Preparation of active zinc oxide from zinc-containing dust and synergistic recovery process of valuable elements

Zinc-containing dust generated from the iron and steel industry is enriched with a large amount of heavy metal substances and rare elements, which is a hazardous waste and a secondary resource. In this study, a new process for the preparation of active zinc oxide and synergistic recovery of valuable elements using zinc-containing dust was proposed. Firstly, a fire process was used to make the valuable components such as Zn, Cd, K, Na, Pb, Bi, In and Sn secondary enriched in the zinc-rich dust. Then the leaching and recovery of K (99.74 %) and Na (98.12 %) were realized by alkaline washing method taking advantage of the solubility difference. Thermodynamic analysis showed that controlling the pH of the leaching system could realize the selective separation of the valuable components. The experimental results showed that the leaching rates of Zn and Cd reached 86.95 % and 92.28 %, respectively, under the optimal experimental conditions, while Pb, Sn, Bi and In were enriched in the neutral leaching slag. Cd sponge (70.3 %) was obtained after the neutral leach solution was treated by Zn powder replacement process. The purified zinc sulfate solution was used to prepare active zinc oxide (97.04 %) by direct precipitation at a molar ratio of CO32–/Zn2+ of 1.15 and a temperature of 50 °C. The average particle size of the product was 21.95 nm, which was in accordance with the industry standard. Neutral leaching slag realized Bi (91.5 %), Sn (71.01 %) and In (94.0 %) in high acid leaching process, and Pb was enriched in slag in the form of PbSO4. The high acid leach solution is hydrolyzed, extracted and replaced to obtain BiOCl, crude tin and crude indium. This process realizes the comprehensive recovery and high-value utilization of various valuable elements in zinc-containing dust sludge, and has significant environmental, economic and social benefits.

Harnessing Magnetic Nanoparticles for the Effective Removal of Micro- and Nanoplastics: A Critical Review.

The spread of micro- (MPs) and nanoplastics (NPs) in the environment has become a significant environmental concern, necessitating effective removal strategies. In this comprehensive scientific review, we examine the use of magnetic nanoparticles (MNPs) as a promising technology for the removal of MPs and NPs from water. We first describe the issues of MPs and NPs and their impact on the environment and human health. Then, the fundamental principles of using MNPs for the removal of these pollutants will be presented, emphasizing that MNPs enable the selective binding and separation of MPs and NPs from water sources. Furthermore, we provide a short summary of various types of MNPs that have proven effective in the removal of MPs and NPs. These include ferromagnetic nanoparticles and MNPs coated with organic polymers, as well as nanocomposites and magnetic nanostructures. We also review their properties, such as magnetic saturation, size, shape, surface functionalization, and stability, and their influence on removal efficiency. Next, we describe different methods of utilizing MNPs for the removal of MPs and NPs. We discuss their advantages, limitations, and potential for further development in detail. In the final part of the review, we provide an overview of the existing studies and results demonstrating the effectiveness of using MNPs for the removal of MPs and NPs from water. We also address the challenges that need to be overcome, such as nanoparticle optimization, process scalability, and the removal and recycling of nanoparticles after the completion of the process. This comprehensive scientific review offers extensive insights into the use of MNPs for the removal of MPs and NPs from water. With improved understanding and the development of advanced materials and methods, this technology can play a crucial role in addressing the issues of MPs and NPs and preserving a clean and healthy environment. The novelty of this review article is the emphasis on MNPs for the removal of MPs and NPs from water and a detailed review of the advantages and disadvantages of various MNPs for the mentioned application. Additionally, a review of a large number of publications in this field is provided.

Novel PEI/Zein core–shell composite as mixed-mode stationary phase for high performance liquid chromatography

Based on the adhesion of polyethyleneimine (PEI), a novel PEI/zein co-modified core-shell stationary phase (PEI/Zein@SiO2) was prepared by doping zein to form a composite modification layer. The stationary phase achieved effective separation of nucleosides, bases and antibiotics in hydrophilic interaction mode on account of the hydrophilic groups of composite coating. With the hydrophobicity of zein, the flavones could be separated in reversed-phase mode. In short, the separation and analysis of hydrophilic/hydrophobic compounds were accomplished excellently by the PEI/Zein@SiO2 column with mixed double mode. The prepared chromatographic stationary phase not only avoided the dissolution of zein, but also covered the strong adsorption of some analytes caused by silica hydroxyl groups on the surface of silica spheres. The morphological structure and specific surface area of the material were reflected by various characterization techniques. Hydrophilic/hydrophobic compounds were used as tested analytes to research separation performance and retention mechanisms of PEI/Zein@SiO2 column. The stability and reproducibility of the PEI/Zein@SiO2 stationary phase were satisfied. Therefore, the modification of zein could improve the separation selectivity of stationary phase effectively for complex samples, which had the potential to be one of the significant potential application materials in stationary phase packing.

Monte Carlo Simulations of Water Pollutant Adsorption at Parts-per-Billion Concentration: A Study on 1,4-Dioxane.

1,4-dioxane, an emerging water pollutant with high production volumes, is a probable human carcinogen. The inadequacy of conventional treatment processes demonstrates the need for an effective remediation strategy. Crystalline nanoporous materials are cost-effective adsorbents due to their high capacity and selective separation in mixtures. This study explores the potential of all-silica zeolites for the separation of 1,4-dioxane from water. These zeolites are highly hydrophobic and can preferentially adsorb nonpolar molecules from mixtures. We investigated six zeolite frameworks (BEA, EUO, FER, IFR, MFI, and MOR) using Monte Carlo simulations in the Gibbs ensemble. The simulations indicate high selectivity by FER and EUO, especially at low pressures, which we attribute to pore sizes and shapes with a greater affinity to 1,4-dioxane. We also demonstrate a Monte Carlo simulation workflow using gauge cells to model the adsorption of an aqueous solution of 1,4-dioxane at a 0.35 ppb concentration. We quantify 1,4-dioxane and water coadsorption and observe selectivities ranging from 1.1 × 105 in MOR to 8.7 × 106 in FER. We also demonstrate that 1,4-dioxane is in the infinite dilution regime in the aqueous phase at this concentration. This simulation technique can be extended to model other emerging water contaminants such as perfluoroalkyl and polyfluoroalkyl substances (PFAS), chlorofluorocarbons, and others, which are also found in extremely low concentrations.

Sequential assembly enhanced selectivity on magnetic imprinted polymers for specific capture of naringin: A combination of synergistic dual sites and imprinted effect

Green and sustainable recovery of high-value natural flavonoids in agricultural wastes could not only improve natural resource utilization, but also could effectively reduce environmental pollution. Recently, great efforts have been made for research on the development of magnetic imprinted composite adsorbent, but the simultaneous promotion of stable selectivity and high adsorption amounts still faces its challenges. Inspired by “Sandwich-like” transport channels with proper steric and specific affinity sites, herein we designed a new kind of surface-imprinted magnetic colloidal nanocrystal clusters (MCNCs) with dual recognition sites (MCNCs@DR-MIPs) via sequential surface imprinted strategy. A two-step sequential surface-initiated atom transfer radical polymerization (SI-ATRP) was employed to construct the double imprinted sites, which can significantly improve the adsorption selectivity and adsorption amounts. In this design, the metal ion Zn(II) and the low pKa boronic acid APBA (1-allylpyridine-3-boronic acid, pKa = 7.4) could effectively tune the appropriate yolk-shell confinement sites, the obtained artificial double imprinted binding sites establishes the promising chemical environment for selective separation. As expected, the adsorption equilibrium experiments exhibited adsorption kinetics (180 min) and the maximum equilibrium binding capacity (34.60 µmol g−1). In virtue of unique advantages of magnetic separation materials, this novel absorbent exhibited a green and environmentally friendly enrichment process for naringin (NRG). Meanwhile, MCNCs@DR-MIPs showed excellent selectivity (imprinted factor 2.15) and regeneration properties (only decreased by 8.22 % after 7 cycles) for NRG. Additionally, the commercially available NRG could be effectively extracted and concentrated to 94.78 %. This study offers a sustainable effective strategy for flavonoids purification of magnetic separation materials and promotes advance the other natural compounds from agricultural wastes.

High antifouling graphene membranes with Fe2O3 nanoparticles in-situ intercalation for selective dye/salt separation

Effective organic dyes selective separation from high salinity textile wastewater consisting of inorganic salts and organic dyes is of great significant for the textile wastewater treatment. Graphene oxide (GO) have been used widely to form ultrathin high-permeance membrane for molecular and ionic sieving. However, swelling and membrane fouling of GO membrane hampered its practical applications. In this work, high stability and antifouling reduced graphene oxide (rGO) membranes were prepared, and Fe2O3 nanoparticles was used as intercalation to turn the membrane interlayer spacing. The rGO/2Fe2O3 nanocomposite blended membrane exhibited high permeance of 24.90 L m−2 h−1 bar−1, excellent organic dyes rejection (98.15 % and 98.69 % for methylene blue and Evans blue, respectively) and low salt retention (6.26 % for NaCl). Meanwhile, this membrane demonstrated a superior selective dye/salt separation factor up to 232 with a high rejection of 99.59 % to Evans blue and a lower salt rejection of 5.03 % to NaCl. Furthermore, nanofiltration experiments towards Evans blue/NaCl mixed solution indicated that the membrane also exhibited excellent antifouling performance with flux recovery rate of >86 % after six fouling/backwash cycles. Therefore, our work may provide a promising idea for the development of two-dimensional nanofiltration membranes for efficient high salinity textile wastewater treatment.

Interfacial modification of recombinant protein for immunoglobulin G adsorption with spindle-shaped MOF as nano molecular containers

Development of fresh solid phase extractant is critical for selective separation and purification of special proteins. Herein, we demonstrated a recombinant Staphylococcal Protein G (rSPG) with a His-tag modified the novel single-metal organic framework (rSPG@Ni-MOF-74). The proposed solid-phase extraction material possessed a uniform spindle-shaped structure, large surface area (709.60 m2 g−1) and pore volume (0.08 m3 g−1), high metal content (22.57 wt%), which facilitated the interaction between host and guest. As results, the composite displayed outstanding selective recognition and adsorption of IgG, due to synergistic effect of the binding ability of rSPG with the Fc region of IgG, maintained through hydrogen bonding and electrostatic attraction, as well as hydrophobic interaction. The adsorption performance and mechanism of rSPG@Ni-MOF-74 have been fully investigated. Additionally, the rSPG@Ni-MOF-74 composite could effectively separate IgG from serum obtained from healthy humans, with the purity of the separated IgG verified through SDS-PAGE analysis. Furthermore, LC-MS/MS analysis identified a high content of IgG (55.3 %) in the eluate from rSPG@Ni-MOF-74, suggesting the great potential of rSPG@Ni-MOF-74 in IgG separation and enrichment from complex matrix.

Silk fibroin-graphene oxide composite membranes for selective separation of ions and molecules from water

Nanofiltration membranes with controlled pores are useful in many fields, such as pharmaceuticals, desalination, petroleum, and food processing. Recently, graphene oxide has emerged as a promising candidate for the fabrication of highly efficient and pressure-resistant nanofiltration membranes with excellent water permeability and solute rejection. However, it remains difficult to achieve increased permeability while maintaining excellent separation ability. Herein, we report a novel silk fibroin-graphene oxide (FGO) composite membrane prepared by using fibroin as a cross-link reagent, which is extracted from natural Bombyx mori silkworm cocoons. Such a FGO membrane shows a pure water permeance of ∼280 L m−2 h−1 bar−1, which is five times greater than previously reported GO-based membranes. Further, such a membrane also exhibits excellent separation efficiency (> 99 %) for different feed molecules. Additionally, these membranes exhibit high chemical stability in water, acidic and basic solutions for several days compared to pristine GO membranes.