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Taking the high-grade nickel matte obtained from the smelting and converting of Jinbaoshan platinum-palladium concentrates as the research object, a hydrometallurgical process of one-stage atmospheric pressure leaching followed by two-stage pressure leaching was used to study the leaching behavior of nickel, cobalt, copper, iron and sulfur, as well as the refining and enrichment of precious metals. The effects of leaching endpoint pH value, leaching temperature, liquid-solid ratio, oxygen partial pressure, reaction time, initial acidity and other factors were investigated. The results show that the control conditions for atmospheric pressure leaching are leaching temperature of 70 °C, leaching time of eight hours, liquid-solid ratio of 6, and the control conditions for the first stage pressure leaching are solution dosage of 500 mL (H2S04 10 g/L, Cu 3.19 g/L), liquid-solid ratio of 10, oxygen partial pressure of 0.2 MPa, leaching time of one hour, and reaction temperature of 150 °C. The control conditions for the second stage pressure leaching are solution dosage of 500 mL (H2SO4 40 g/L), liquid-solid ratio of 10, reaction temperature of 180 °C, oxygen partial pressure of 0.1 MPa, and reaction time of two hours. The leaching rate of nickel and copper in high-grade nickel matte can reach more than 99%, and platinum and palladium are basically not eached, and the enrichment degree of total content of Au, Ag, Pt and Pd is more than 88 times. [ABSTRACT FROM AUTHOR]

The chlorination of oxides of major concern in cassiterite concentrate with various chlorinating agents is investigated in light of their thermodynamic feasibilities to extract and recover their valuable metal components. Mechanisms responsible for the processes and their Gibbs free energy changes as a function of temperature to selectively separate and/or recover the metal(s) of interest and unwanted ones as their metallic chlorides are identified. Attention is given to gaseous (Cl2 and Cl2 + CO mixture) and solid (CaCl2 and MgCl2) chlorine sources, from which Cl2 + CO shows no reaction selectivity for any of the oxides but a feasible metal chloride formation for all. Chlorine gas (Cl2), on the other hand, could selectively form chlorides with metals of +2 oxidation state in their oxides, leaving those of high oxidation state unreacted. MgCl2, unlike CaCl2, is found capable of producing calcium, ferrous, and stannic chloride from their metallic oxides with enhanced reaction tendencies in the presence of silicon dioxide (SiO2). An overall study of the thermodynamic feasibility of all chlorine sources looked at alongside operational and environmental viabilities suitably suggests MgCl2 for a selective extraction of the valuable metal components in a cassiterite concentrate, in which case, moderate temperatures seem promising. [ABSTRACT FROM AUTHOR]

The development of density functional theory (DFT) has significantly enhanced the use of computational chemistry as a tool in the design and development of ligands for the separation of actinides (An) and lanthanides (Ln) in the nuclear waste management. In the past, identifying new ligands involved either making incremental structural changes to existing ligands or conducting extensive laboratory testing of numerous compounds. However, these experimental methods are often costly and time-consuming. With the advancements in hardware and software, theoretical and computational chemistry has become a powerful and cost-effective approach in nuclear waste management research. The density functional theory (DFT), in particular, has played a pivotal role by enabling scientists to accurately predict the effectiveness of ligands based on electronic and molecular properties, as well as reactivity indices. This computational approach provides valuable insights into the separation efficiencies of ligands without the need for extensive experimental efforts. This review highlights the role of computational chemistry in the design of ligands for the separation of lanthanides and actinides in spent nuclear fuel processing. It discusses various design strategies and computational analyses used in ligand optimization, highlighting the potential applications of computational tools in guiding ligand design and improving separation processes. The work emphasizes the synergy between computational insights and experimental observations in lanthanide/actinide chemistry, which enhances understanding of complex phenomena and aids in the interpretation of experimental results. It also explores different design approaches that allow for fine-tuning of ligand properties and selectivity toward specific metal ions, ultimately improving separation efficiency. In this review, we will discuss some widely used computational tools in chemistry without delving into complex mathematical formulas. This will be particularly helpful for researchers who come from an experimental background and may not be as familiar with advanced mathematical concepts. The tools covered are bond order analysis, population analysis, quantum theory of atoms in molecules (QTAIM) analysis, Energy Decomposition Analysis (EDA), and thermodynamic analysis. These methods are explored in a more accessible manner for non-theoretical researchers. They provide valuable insights into bonding, binding, stability, non-bonding interactions, coordinating abilities and selectivity of organic ligands in extraction of actinides and lanthanides, thus providing useful information in the designing of ligands to enhance separation strategies. This review serves as an excellent resource for future ligand design, offering valuable insights into computational techniques used to understand the coordination and complexation behaviors of ligands. Also an attempt has been made to understand the role of DFT functionals in the calculations. It provides a foundation for researchers to comprehend and apply computational tools effectively in their investigations. [ABSTRACT FROM AUTHOR]

The selective flotation separation of gypsum and quartz in phosphogypsum (PG) is an urgent problem that is very important for the high‐value utilization of PG. In the work, dodecyl amine hydrochloride (DH) was introduced as a collector for the selective flotation separation of gypsum and quartz. The flotation property and selective mechanism of DH on the surface of gypsum and quartz were researched by single mineral flotation experiments, Fourier transform attenuated total reflection infrared spectroscopy analyzer, zeta potential analyzer, X‐ray photoelectron spectrum, molecular dynamic (MD) simulation, etc. Additionally, H+ was introduced into the mineral‐water system simulated by MD to take into account the effect of acidic conditions on the adsorption of DH. The pre‐adsorption of H+ on the quartz surface under strongly acidic conditions hindered the electrostatic force adsorption of DH on the quartz surface. Furthermore, DH was adopted as a collector in the direct flotation recovery of gypsum from PG, and the gypsum concentrates with productivity of 69.85%, CaSO4·2H2O content of 96.33%, and whiteness of 55.00% were obtained. The SiO2 content in the gypsum concentrate decreased from 9.08% to 0.616%. It suggested that DH could serve as a promising collector in the selective separation of gypsum and quartz in PG via flotation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A traditional phase transformation method is commonly used to prepare molecular imprinting membranes for selective separation. However, traditional molecularly imprinted polymers are mostly micron-sized particles, and the imprinting sites in their membrane are easily embedded, leading to a reduced adsorption capacity and decreased selectivity. In this study, an ultra-long nanowire with a diameter of about 15 nm was synthesized for the separation of artemisinin (ART), and its adsorption capacity was as high as 198.29 mg g−1 after imprinting polymerization. Molecular imprinting membranes were prepared, using polyvinylidene fluoride (PVDF), polyethersulfone (PES), and polysulfone (PSF) as the membrane matrix, for comparison. The average membrane pore size of PVDF-MIM was about 480 nm, and PVDF-MIM had the highest adsorption capacity (69 mg g−1) for ART. The optimal flow rate for PVDF-MIM's dynamic adsorption of ART was 7 mL min−1. Under this optimal flow rate, selectivity experiments were carried out to obtain the separation factor of PVDF-MIM (α = 8.37), which was much higher than the corresponding values of PES-MIM and PSF-MIM. In addition, the hydrophobicity and low flux of PES-MIM and PSF-MIM lead to higher non-specific adsorption. The hydrophobicity of PVDF-MIM is lower than that of PES-MIM and PSF-MIM, which greatly reduces the non-specific adsorption of the membrane, thus increasing the selectivity of the membranes. Therefore, the effective density of the imprinting sites in the pores and the membrane structure are the main factors determining the efficient separation of molecularly imprinted membranes. [ABSTRACT FROM AUTHOR]

In the context of the circular economy, there is a need for advanced methods to recover metals from industrial waste, yet classical hydrometallurgical techniques are limited. Here, we review ultrasonic-assisted hydrometallurgical leaching with focus on the use of acids, bases, oxidants, bacteria and electrolysis. Oxidative leaching is done with ferric ions, dioxygen, ozone and hydrogen peroxide. Upscaling is also detailed. Ultrasonication allows to reduce the dosage of leaching agents, to reduce reaction time, and to enhance leaching efficiency. Large-scale equipments are still limited by low cavitation efficiency, low throughput, high usage costs, and high energy consumption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste copper sulphate solution was electrolyzed to provide sulphuric acid. • This study obtained leaching rates of 93 % of Ni, 91 % of Co, 89 % of Mn and 92 % of Li. • Recovery rates of 91 % of Ni, 91 % of Co, 86 % of Mn and 90 % of Li were achieved. • A novel method was developed without using any acid or reductant. • This work demonstrated the application of treating waste with waste. Effective recovery of Li, Co, Ni and Mn from cathode materials of spent lithium-ion batteries (LIBs) has become a global concern. In this study, electrolysis of copper sulfate to produce sulfuric acid and electrons were utilized to recover Li, Co, Ni and Mn from spent LIBs. The obtained results showed that 93 % of Ni, 91 % of Co, 89 % of Mn and 94 % of Li were leached and 99 % of Cu was deposited during leaching process by adopting the 0.225 mol/L of copper sulfate with a solid/liquid ratio of 15 g/L at a current density of 50 mA/m2 and 80 °C for 4.5 h. Then, a current efficiency of 72 % for the cathode and 30 % for the anode was achieved at a current density of 40 mA/m2, 70 °C and pH 2.5 during electrodeposition process. The Ni-Co deposition followed the principle of anomalous codeposition and the complete deposition time of Co, Ni and Mn were 3 h, 9 h and 10 h, respectively. Eventually, the Ni, Co, Mn, Li and Cu can be recovered as Ni-Co alloy, MnO 2 and Li 2 CO 3 and Cu metals with the corresponding recovery rates of 99.40 %, 91.00 %, 90.68 %, 85.59 % and 89.55 %, respectively. This study proposes a promising strategy for recycling cathode materials from spent LIBs without addition of chemical reductants and acids. [ABSTRACT FROM AUTHOR]

Nickel-based single-crystal superalloys are designed for extreme conditions due to their superior corrosion and creep resistance properties. However, these pose challenges in the subsequent recycling after reaching their end-of-life. Molten magnesium (Mg) can rapidly corrode the stable spent nickel-based superalloys and selectively dissolve nickel (Ni). This waste-free process represents an effective method for recycling spent superalloys and accomplishing metal regeneration. This study investigates the mechanism of selectively dissolving Ni from DD5, a nickel-based single-crystal superalloy, by optimizing process temperature, time, and Mg content in an inert atmosphere. Vacuum distillation was employed to separate the resulting Mg, residual superalloy (i.e., the material left post-extraction), and Ni-rich alloy (i.e., the metal product selectively extracted). The findings revealed that the residual superalloy after selective Ni dissolution is characterized by a porous skeleton structure with pore sizes predominantly ranging from 2 to 30 nm and a low compressive strength which is 1/10 of the original DD5 superalloy.

Both hydrophobic and hydrophilic pollutions have damage on our environment, and it is necessary to remove them. However, the treatments for different water pollutions can be specific due to the hydrophobicity of various molecules. Therefore, it is important to separate pollutants with different hydrophobicity. In this work, we developed a diffusion separation method based on hydrophobicity selectivity polymer membranes, whose selectivity between hydrophilic and hydrophobic pollutants can be up to more than 100. By doping pH‐responsive monomer into hydrophobic polymer membrane, the permeability of membrane can be tuned by surrounding pH, and the selectivity is not decreasing. With the results of characteristics on contact angle, scanning electron microscope, and mechanical properties, we prove the stimuli‐responsive polymer membrane at different states have similar properties with the nonresponsive amorphous polymer membranes with high separation selectivity. [ABSTRACT FROM AUTHOR]

This study aims to integrate a novel bio-purification process employing an engineered E. coli strain in the downstream processing of lactic acid (LA) fermentation broths from low-cost renewable biological feedstocks. Fermentation broth of candy waste and digestate mixture was used as a real biological feedstock. An engineered E. coli strain that selectively catabolize impurities without catabolizing LA was initially adapted on the biological feedstock, followed by shake flask experiments to prove the bio-purification concept. Scale-up and validation in a bench-scale bioreactor followed, before developing a semi-continuous membrane bioreactor (MBR) bio-purification process. The MBR bio-purification was assessed with biological feedstocks which simulated ultrafiltration or nanofiltration permeates. Incomplete removal of impurities and increased fouling was observed in the case of the ultrafiltration permeate. Contrarily, the nanofiltration permeate was successfully treated with MBR bio-purification, since low membrane fouling, 100% maltose and acetic acid removal, and no LA catabolism was achieved. MBR bio-purification as a post-treatment step in the downstream processing of LA was demonstrated as a promising technology for increasing the purity of LA solutions. [ABSTRACT FROM AUTHOR]

The sorting of nano- and microparticles according to different properties is an industrially highly relevant but partly unsolved problem. In this study, we investigate the sorting of a complex microparticle mixture on the basis of their different properties by insulator-based dielectrophoretic filtration at high throughput. We demonstrate here that such a high selectivity demanding sorting process is possible in a single device thanks to recent advances in the development of dielectrophoretic filters, which has been shown using simple binary mixtures in a previous study. In that study, a filter with a regular structure (mesh) is introduced with pores several orders of magnitude larger than the target particles so that the particles are trapped solely by the action of positive dielectrophoresis. In this work, we demonstrate the improvement of the filter design, by comparing the trapping behavior to an alternative, irregular porous ceramic structure as a filter medium. A significantly higher selectivity for positive dielectrophoresis could be reached using the regular mesh structure. This high selectivity enables a stepwise operation mode, combining a selective trapping step and several subsequent selective remobilization steps. A mixture of polystyrene-based particles could be sorted by size, shape, and surface coating in one pass of the filter. The proposed method is therefore a promising technique to efficiently create highly specific particle systems in the future.

Due to the substantial volume of waste produced and the potential for high-value bioactive compounds to be extracted from potato peel, the valorization of industrial waste of potato processing industry is the subject of this research. The study presents an innovative technique for efficient extraction of 4-hydroxybenzoic acid (P-HBA), a valuable bioactive molecule, from potato peel extract by utilizing molecularly imprinted chitosan beads (MICB). The MICB was synthesized using environmentally benign cross-linkers such as Tetraethyl orthosilicate (TEOS), Sodium triphosphate (STPP), while P-HBA was is used as a template. The MICB was investigated using FTIR, SEM, and EDAX. Adsorption studies were conducted to optimize parameters like adsorbent dose, solution concentration, time and pH. A recovery rate of 95.07 % is recorded from a synthetic P-HBA solution when measured by HPLC while from the actual potato processing industrial effluent the same is 40 %. The adsorption capacity of MICB is 67.5 mg g−1 and specific binding capacity is 20.62 mg g−1 which remained unchanged for six consecutive cycle reuse. This is the first study to report uptake of a bioactive molecule from actual potato processing industry waste. [ABSTRACT FROM AUTHOR]

Zinc and cadmium were recovered by acid leaching--vulcanization impurity removal method from dust of slide blowing--fuming process for treating jarosites, and copper was selectively removed from the leaching solution by sulfide precipitation. Subsequently, the obtained purified solution will be used to prepare Cd-doped ZnS composites. Based on the thermodynamic analysis, the influencing factors and kinetics of zinc leaching rate in sulfuric acid system were investigated, and the influence of various parameters on sulfidation was elucidated through orthogonal tests. The results show that the zinc in dust mainly exists in the form of zinc oxide, the leaching reaction follows a mixed control model with a 73.70 kJ/mol activation energy. Zinc leaching rate can reach 98.99% under the optimum conditions. The copper removal rate can reach 95.97% under 3.2 theoretical times of Na2S addition at pH of 2.0, with high retaining rate of Zn and Cd, achieving effectively selective separation of copper from zinc and cadmium. [ABSTRACT FROM AUTHOR]

MIL-101(Cr), a class of metal-organic framework, is a potential candidate for CO2 capture applications because of its high capacity of adsorption and separation capability. However, the intrinsic microporous structure of this nanomaterial poses limitations on its adsorption kinetics. Techniques employed to enhance its adsorption kinetics often adversely impact its adsorption capacity at equilibrium. Herein, as a new approach, we prepared amine-functionalized FAC@MIL-101(Cr) composites with adjustable micro-mesoporous structure and tunable nitrogen content by embedding different ratios of amine-functionalized activated carbon throughout the framework of MIL-101(Cr). This led to a simultaneous improvement in both kinetics and adsorption capacity for CO2. The best adsorbent, FAC-6@MIL-101(Cr), has excellent textural properties with a high surface area (1763.1 m2.g−1), great pore volume (1.29 cm3.g−1), and suitable nitrogen content (4.7 wt%). The adsorption analysis revealed that the modification of MIL-101(Cr) improved its CO2 adsorption capacity from 3.21 to 5.27 mmol/g under standard conditions of 1 bar and 25 °C. Furthermore, the FAC-6@MIL-101(Cr) adsorbent demonstrated fast CO2 adsorption kinetics (three times more relative to the pure MIL-101(Cr)), high CO2/N2 selectivity, and remarkable cyclic stability. The results confirmed that hybridization enhanced the polarizability of FAC@MIL-101(Cr) samples, causing more robust CO2-adsorbent surface interactions. Simultaneously, the existence of mesopores in the structure facilitated the transport of CO2 into the interior pores, resulting in a more efficient contact of CO2 molecules with all of the amine sites and a faster adsorption rate as well as more efficient regeneration. According to density functional theory (DFT) calculations, hybridization process induces significant changes in composites’ electronic structure, enhancing their capacity to interact with CO2 molecules more effectively. On the other hand, DFT calculations confirm that N2 molecule is less activated on the FAC@MIL-101(Cr) as evidenced by calculated small adsorption energy and charge-transfer values.

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.

The chlorination of oxides of major concern in cassiterite concentrate with various chlorinating agents is investigated in light of their thermodynamic feasibilities to extract and recover their valuable metal components. Mechanisms responsible for the processes and their Gibbs free energy changes as a function of temperature to selectively separate and/or recover the metal(s) of interest and unwanted ones as their metallic chlorides are identified. Attention is given to gaseous (Cl2 and Cl2 + CO mixture) and solid (CaCl2 and MgCl2) chlorine sources, from which Cl2 + CO shows no reaction selectivity for any of the oxides but a feasible metal chloride formation for all. Chlorine gas (Cl2), on the other hand, could selectively form chlorides with metals of +2 oxidation state in their oxides, leaving those of high oxidation state unreacted. MgCl2, unlike CaCl2, is found capable of producing calcium, ferrous, and stannic chloride from their metallic oxides with enhanced reaction tendencies in the presence of silicon dioxide (SiO2). An overall study of the thermodynamic feasibility of all chlorine sources looked at alongside operational and environmental viabilities suitably suggests MgCl2 for a selective extraction of the valuable metal components in a cassiterite concentrate, in which case, moderate temperatures seem promising.

A traditional phase transformation method is commonly used to prepare molecular imprinting membranes for selective separation. However, traditional molecularly imprinted polymers are mostly micron-sized particles, and the imprinting sites in their membrane are easily embedded, leading to a reduced adsorption capacity and decreased selectivity. In this study, an ultra-long nanowire with a diameter of about 15 nm was synthesized for the separation of artemisinin (ART), and its adsorption capacity was as high as 198.29 mg g−1 after imprinting polymerization. Molecular imprinting membranes were prepared, using polyvinylidene fluoride (PVDF), polyethersulfone (PES), and polysulfone (PSF) as the membrane matrix, for comparison. The average membrane pore size of PVDF-MIM was about 480 nm, and PVDF-MIM had the highest adsorption capacity (69 mg g−1) for ART. The optimal flow rate for PVDF-MIM’s dynamic adsorption of ART was 7 mL min−1. Under this optimal flow rate, selectivity experiments were carried out to obtain the separation factor of PVDF-MIM (α = 8.37), which was much higher than the corresponding values of PES-MIM and PSF-MIM. In addition, the hydrophobicity and low flux of PES-MIM and PSF-MIM lead to higher non-specific adsorption. The hydrophobicity of PVDF-MIM is lower than that of PES-MIM and PSF-MIM, which greatly reduces the non-specific adsorption of the membrane, thus increasing the selectivity of the membranes. Therefore, the effective density of the imprinting sites in the pores and the membrane structure are the main factors determining the efficient separation of molecularly imprinted membranes.

Nickel ion imprinted polymer (Ni-IIP) was prepared using microwave-assisted surface imprinting technique with Ni2+ as the template, salicylaldehyde-ethylenediamine Schiff base as functional monomers, ethylene glycol dimethacrylate as a crosslinking agent and alkylated silica gel as a carrier. Fourier transform infrared spectroscopy (FTIR) was used to characterize Ni-IIP, which confirmed the successful synthesis of the polymer. Scanning electron microscopy (SEM) was used to compare the surface morphology of Ni-IIP to non-imprinted polymer (NIP). The SEM analysis found that Ni-IIP had many holes on its surface and abundant spherule structures after elution, while NIP only had a few irregular holes on its surface. The adsorption performance of IIP was studied under different conditions, including pH, temperature, and initial concentration of Ni. The experimental results showed that the maximum adsorption capacity of IIP for Ni was 24.23 mg g–1 at pH 8, temperature of 30°C, adsorption time of 40 min, and initial concentration of Ni of 30 mg L–1. The pseudo-second-order kinetic equation could better describe the whole adsorption process, suggesting that chemical adsorption mainly controlled the adsorption process of nickel ions. The Langmuir adsorption isotherm model showed a high linear relationship, and the theoretical adsorption capacity was closer to the actual adsorption capacity, indicating that the adsorption of nickel ions by IIP and NIP occurred in a single layer. Selective experiments showed that IIP had specific selectivity for nickel ions compared with Cu2+, Zn2+, and Cd2+. The results obtained from the analysis of regeneration and practical application demonstrate the promising potential of the prepared Ni-IIP for the efficient removal of nickel pollutants from water sources. These findings provide a new approach to the removal of Ni from wastewater. [ABSTRACT FROM AUTHOR]

The use of recycling materials from demolished concrete as raw material for structural application represents an opportunity for decreasing the consumption of primary raw materials and waste generation, thus increasing global sustainability. However, this potential is nowadays not fully exploited due to standards limitations and concerns from the construction industry about the negative effect of the recycled sand in the fresh and hardened concrete performance. Thus, most of the recycled sand produced is only reused as roadbed or dumped in the landfill, whereas the recycled coarse aggregate is commonly downcycled when used for lower‐grade applications. This paper presents an overview of the quality properties of recycled materials obtained through advanced recycling technologies designed to separate high‐quality sand and coarse aggregates from hardened cement paste in demolished concrete. The study focuses on evaluating the selective separation technologies implemented in various industrial pilots and examining how the properties of recycled sands and aggregates compare to those of virgin materials of good quality, and their impact on performance. The test results indicate that there is a strong link between recycled sand quality and its effect on workability and strength development of cement‐based materials. This study also identifies critical aggregate parameters based on which one can come up with realistic replacement levels of natural with recycled sands and aggregate without compromising performance in fresh and hardened state. Our intention is to provide sufficient evidence to specifiers and designers that good quality recycled sands can be used in larger amounts in structural concrete. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry & Industry of Forest Products is the property of Chemistry & Industry of Forest Products Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Xenon and krypton are widespread useful noble gases in commercial lighting, lasers, electronics, and medical industry. At the same time, radioactive noble gases may proliferate from used nuclear fuel and diffuse in open atmospheres. Metal organic frameworks as hotspot porous materials for gases uptake and separation are considered to be potential solutions. In this review, we comprehensively summarized recent researches on metal organic frameworks for selective capture and separation of xenon and krypton. Particularly, we followed the aspects of different optimal design strategies, including optimal pore/cage size and geometry, open metal sites, ions (anions and cations), and polar functional groups for enhancing the xenon adsorption and separation performances. Meanwhile, a comparison of each strategy and the mechanisms of xenon/krypton separation were pointed out. The separation of krypton from gases mixtures by dual-bed systems was further discussed. Finally, some existing challenges and opportunities for possible real applications were proclaimed. [ABSTRACT FROM AUTHOR]

In this study, a new 3D porous PVDF-foam-imprinted membrane (PPIM) for the selective separation of artemisinin (ART) was first prepared via the dopamine adhesion of pre-synthesized MIPs into the interior of the PPIM. In the PPIM, the pre-synthesized molecularly imprinted polymers (MIPs) with artesunate (ARU) as a dummy template were uniformly loaded on the interior of the membrane, avoiding the defects of recognition site encapsulation found in the conventional membrane. This membrane also exhibited excellent flux, which is beneficial in practical separation applications. The PPIM was systematically characterized via FT-IR, SEM, pore-size distribution analysis, water contact angle test, membrane flux, and mechanical performance analysis, respectively. In the static adsorption experiment, the pseudo-second-order kinetic model better fitted the rebinding data of ART. Under dynamic conditions, the ART adsorption capacity of the PPIM could be further remarkably improved by tailoring the flow rate to 3 mL min−1. In the selective separation experiment, with artemether (ARE) as the competition substrate, the selective separation ability (α) of the PPIM towards ART/artemether (ARE) reached its peak value (3.16) within only 10 min at this flow rate, which is higher than that of porous PVDF foam non-imprinted membranes (PPNM) (ca. 1.5), showing great separation efficiency in a short time. Moreover, the PPIM can be reused five times without a significant decrease in its adsorption capacities, showing good regeneration performance. This work highlights a simple strategy for constructing new MIMs with high flux and great mechanical strength to achieve the efficient selective separation of ART and ARE in practical applications. [ABSTRACT FROM AUTHOR]

With the rapid development of electronic technology, the electroless copper–nickel plating process produces a significant amount of copper–nickel complex wastewater. The traditional methods face difficulties in achieving wastewater treatment and recovering valuable metal resources. In this study, we propose a new environmentally friendly and efficient treatment process for the separation and recovery of Cu(II) and Ni(II). The photocatalyst TiO2-500, calcined at 500 °C, exhibits excellent photo-reduction performance, selectively reducing Cu(II) in the hybrid wastewater to copper. Even after 5 cycles, TiO2-500 photocatalyst maintains good catalytic performance. Following Cu removal, the remaining Ni(II) in the residual wastewater is effectively adsorbed by a chitosan (CS) membrane with an adsorption capacity of 76.7 mg/g. The separation ratio of Cu–Ni reaches 6290.37 in the photocatalytic process. We conducted a comprehensive investigation of the factors that influence the selective recovery of Cu and Ni ions. Our findings reveal that the disparity in reduction potentials between Cu2+ and Ni2+ plays a crucial role in achieving effective separation of Cu and Ni in chemical plating wastewater through photocatalysis. Specifically, under the experimental conditions described in this paper, the reduction potential of Ni2+ (E(Ni2+/Ni) = − 0.33 V) presents a significant challenge for its photoreduction on TiO2-500, which has a conduction potential of − 0.31 V. Moreover, the catalyst surface carries a positive charge and exhibits weak adsorption of Ni2+, resulting in the majority of Ni2+ ions remaining in solution. This characteristic facilitates subsequent adsorption and separation of Ni2+ ions.Additionally, we further elucidated the mechanisms underlying these two processes. The establishment of this process holds immense significance for treating Cu–Ni mixed wastewater and recovering valuable heavy metal resources. [ABSTRACT FROM AUTHOR]

Surface grafting has been widely used to tune hydrophilicity and chargeability of nanofiltration membranes for reducing membrane fouling potential. However, surface grafting typically leads to a significant pore narrowing and resultant permeability loss, and monocharged surface still struggles to resist mixed foulants with different charges. Herein, ionic liquid (IL)‐ethanol (EtOH) solution containing polyethyleneimine (PEI) is used to rearrange the nascent polyamide layer. The high affinity of IL to the PA layer and the low diffusion steric hindrance of EtOH contribute to the polyamide swelling and PEI deep grafting, during which the "self‐regulation" effect (larger pores would be filled with more PEI molecules) narrows the pore size distribution and enhances hydrophilicity. The nearly charge‐neutral and smooth separation layer shows impressive antifouling capacity to hydrophobic macromolecules and mixed charged molecules, along with long‐term operating stability for real wastewater treatment. This study emphasizes the importance of solvent properties on the membrane grafting behavior. [ABSTRACT FROM AUTHOR]

The current state of separation technology often neglects the multidimensional nature of real particle systems, which are distributed not only in terms of size, but also in terms of other properties, such as surface charge. Therefore, the aim of this study is to experimentally investigate the applicability of magnetic seeded filtration as a multidimensional separation process. Magnetic seed particles are added to a multisubstance suspension, and a selective heteroagglomeration with the nonmagnetic target particles is induced, allowing for an easy subsequent magnetic separation. The results show that high separation efficiencies can be achieved and that the parameters pH and ionic strength govern the agglomeration process. Selective separation based on surface charge was observed, but undesirable heteroagglomeration processes between the target particles lead to a loss of selectivity. Particle size was clearly identified as a second relevant separation feature, and its partially opposite influence on collision frequency and collision efficiency was discussed. Finally, experimental data of multidimensional separation are presented, in which a size-distributed two-substance suspension is separated into defined size and material fractions in a single process step. This study highlights the need for multidimensional evaluation in general and the potential of magnetic seeded filtration as a promising separation technique.

Zinc oxide minerals (primarily smithsonite and hemimorphite) are important sources of Zn. Flotation is the most widely used method of enriching zinc oxide minerals for mineral processing. Chelating reagents have received extensive attention for the flotation of zinc oxide ores because of their high selectivity and stability. This paper systematically summarizes the selective separation performance and mechanisms of various chelating reagents as collectors, activators, and depressants in the flotation of zinc oxide ores. The types and mechanisms of chelating reagents in the flotation of zinc oxide ores are discussed, providing new ideas for the development of efficient flotation reagents for zinc oxide ores. [ABSTRACT FROM AUTHOR]

Domestic and world tendencies of involvement in the processing of ores of rare metals (RMs) and rare-earth metals (REMs) are shown. It is shown that the main direction of innovative activity is the development and application of modern breakthrough technologies for complex processing of mineral raw materials with the production of high-quality products while minimizing environmental damage. The main deposits of rare and rare-earth metals are systematized from the standpoint of the content of the main components, concentrator minerals and the main enrichment methods. The main principal technological schemes of processing of some deposits of RMs and REMs in Russia (Lovozer, Tomtor, and Afrikand deposits) are given. Options for involving technogenic and off-balance raw materials in the processing in order to extract strategic metals are considered. It is substantiated that innovative environmentally friendly processes for the extraction of rare and rare-earth metals from complex ores of complex material composition are being actively developed in Russia at present. [ABSTRACT FROM AUTHOR]

The efficient and sustainable separation of aromatics from aliphatics is an ongoing challenge in chemical engineering. In this work, the protic ionic liquid N‐methylpyrrolidonium methanesulphonate ([NMP][MSA]) was used to separate toluene from n‐heptane or cyclohexane. Nuclear magnetic resonance and Fourier‐transform infrared spectroscopy were used to demonstrate the successfully synthesis of [NMP][MSA]. Density functional theory (DFT) calculations were used to confirm that the interaction of [NMP][MSA] with toluene would be stronger than those with n‐heptane and cyclohexane, with electrostatic forces and dispersion playing the primary roles and induction playing a minor role. Furthermore, independent gradient model (IGM) analysis demonstrated that van der Waals forces make a major contribution to the stability of [NMP][MSA]–toluene. For a 10 mol% toluene/n‐heptane system, the toluene distribution coefficient and selectivity were found to be 0.35 and >70, respectively, while the corresponding values were 0.40 and 27 for a 10 mol% toluene/cyclohexane system. Changing the extraction temperature seemed to have little effect on separation performance. The effects of solvent dosage, initial concentration, and extractant recycling were also investigated. Overall, our results show that [NMP][MSA] has potential for industrial use. [ABSTRACT FROM AUTHOR]

BACKGROUND: Scandium (Sc) is widely used due to its excellent properties such as high melting point, high boiling point, low density, and good stability. However, as a typical dispersed element, Sc usually exists as an associated mineral. Sc needs to be recovered from the production of ore residues and tailings by-products of other metals, the production of main products from Sc containing internal (external) deposits, or from industrial wastewater and waste residue. Among numerous technologies for separating Sc, the adsorption method exhibits promising prospects due to its advantages of simple operation and high recovery. Currently, several materials including silicon-based (such as SAB-15), biomaterials, and metal organic framework, have been used for the separation of Sc(III). Although these adsorbents exhibit good adsorption ability for Sc(III), the inherent structural drawbacks such as poor chemical stability and with only one type of functional group result in the poor selectivity and inferior adsorption capacity, thereby greatly hindering their practical applications. Considering that acid treatment is often required when processing raw materials such as Sc containing tailings, it is crucial to prepare adsorbents that can efficiently and selectively recover Sc(III) in acidic media. Covalent organic polymers are porous organic polymer materials connected by covalent bonds. Due to their adjustable chemical structure, tunable pore size, and easy functionalization, they can be custom-made according to the characteristics of target ions. As one type of alternative adsorbents, they exhibit promising prospects. The pore size matching effect is conducive to achieving the efficient adsorption of target ions in acidic systems. However, because the pore size of the vast majority of covalent organic polymers currently synthesized is much larger than those of metal ions, this method is generally applicable to larger sized ions such as hydrated uranium ions. The utilization of ion imprinting technology or the ingenious selection of monomers with size matching cavities with the target ion to prepare covalent organic polymers are effective for address these issues. However, the complex preparation process makes it difficult to scale up. For covalent organic polymers, modification with special functional groups is another effective strategy to improve their adsorption performance. To tackle the issue of limited binding ability caused by the single functional group, research has shown that the introduction of various functional groups into the porous skeleton structure can effectively enhance the selective binding ability to target ions by utilizing the synergistic effect between different groups. OBJECTIVES: To improve the adsorption performance of porous organic polymers for Sc(III) in acidic media by utilizing the synergistic effect of multiple functional groups. METHODS: Phloroglucinol (1mmol) and hexachlorocyclotriphosphazene (0.5mmol) were dissolved in 1mL of 1,4- dioxane, followed by the addition of 0.84mL of triethylamine. The mixture was transferred to a hydrothermal reactor (8mL) and reacted at 80℃ for 24h. The product was washed several times with water, ethanol and acetone, respectively. Finally, CPF-T was prepared by vacuum drying at 50℃ for 12h. CPF -T-COOH was prepared according to the same procedure by changing phloroglucinol with 2,4,6-trihydroxybenzoic acid. The infrared spectra of the CPF-T and CPF-T-COOH were collected by Thermo Scientific Nicolet iS20 Fourier transform infrared spectrometer (FT-IR) (Thermo, USA). The microstructure of the polymers was studied using SU8010 scanning electron microscope (SEM) (Hitachi, Japan). The thermogravimetric analysis (TGA) curve of the polymers was collected by the DTA7200 TGA instrument (Hitachi, Japan) under N2 conditions (N2 flow rate: 20mL/min; heating rate: 10K/min). The elemental information of the materials was analyzed using Thermo Scientific K-Alpha X-ray photoelectron spectrometer (XPS) (Thermo, USA). The N2 adsorption desorption isotherm was measured at 77K using the Micromeritics APSP2460 4-station fully automatic specific surface area analyzer (Micromeritics, USA). The sample was vacuum degassed at 120℃ for 12h before measurement. Adsorption experiments were conducted at room temperature using a constant temperature oscillator (150r/min). The adsorbent dosage was 1g/L, and the experimental data was obtained as the average of three parallel experiments. After adsorption, the supernatant was collected by filtration with 0.45μm microporous membrane. Subsequently, it was tested by EXPEC 6000 ICP-OES (Hangzhou Puyu Technology Development Co., Ltd.), and the linear correlation coefficient (R² ) of the standard curve equation was >0.999. CPF-T and CPF-T-COOH were characterized by FT-IR, SEM, TGA and N2 adsorption-desorption analysis. The appearance of P-O-Ar, P=N, and P-N stretching vibration peaks in the FT-IR diagram indicates the successful crosslinking of the organic monomers. In addition, the appearance of C=O, C-O and -OH in CPF-TCOOH indicates the successful modification of —COOH. TGA characterization indicates that the resulting materials have a good thermal stability within 150℃. Through SEM images, it can be observed that the micro morphologies of the two materials are different. CPF-T presents a relatively smooth spherical structure with some agglomerating, CPF-T-COOH exhibits an irregular, ant-like porous structure with a rough surface. The N2 adsorption-desorption isotherms of both materials belong to type II and show a strong absorption in the range of P/P0=0.8−1.0, indicating the presence of microporous and mesoporous structures. The specific surface area of CPFT is 76.5m² /g, and total pore volume is 0.38cm3 /g. The specific surface area of CPF-T-COOH is 2.61m² /g, and the total pore volume is 0.035cm3 /g. The adsorption performance of CPF-T and CPF-T-COOH for Sc(III) was investigated through batch adsorption experiments, including the influence of solution pH, adsorption kinetics, adsorption isotherms and adsorption selectivity. The adsorption efficiencies of Sc(III) on the two materials exhibit different trends with respect to the solution pH. As the acidity of the solution increases, the adsorption efficiency of CPF-T for Sc(III) significantly decreases, and at pH<3, the adsorption rate is below 60%. However, within the range of solution pH=1-3, the adsorption efficiency of CPF-T-COOH for Sc(III) remains above 95%. The adsorption kinetics experiment shows that CPF-T reaches adsorption equilibrium within 120min, while CPF-T-COOH can reach adsorption equilibrium within 30min. In addition, in the adsorption isotherms experiment, the maximum adsorption capacity of CPF-TCOOH (64.6mg/g) for Sc(III) was higher than that of CPF-T (22.5mg/g). Finally, the adsorption selectivity was evaluated through coexisting ion experiments. Both materials have the ability to selectively adsorb Sc(III), with Kd values of 5.1×10²mL/g and 4.0×10³mL/g for Sc(III), respectively. The adsorption performance of CPF-T-COOH is not only higher than that of CPF-T, but also has unique advantages compared to some reported adsorbents, including a wider pH range, fast adsorption equilibrium time, and higher Kf value. These results indicate that the synergistic effect of multiple adsorption sites is an effective strategy for improving adsorption affinity of adsorbents. The adsorption mechanism was studied through XPS analysis. In the high-resolution XPS spectrum of N1s of Sc(III) loaded sample, all the binding energies of P-NH-P(398.0eV), P=N-H(399.3eV) and P-NH2 (401.6eV) show an increase, shifting to 398.1eV, 399.6eV and 403.5eV, respectively. Meanwhile, in the spectra of O1s, it can also be observed that the binding energies of C=O(534.2eV), C-OH(533.2eV), C-O(532.0eV) and P-O(531.0eV) shift to 534.3eV, 533.3eV, 532.2eV and 531.3eV, respectively. These results indicate the existence of coordination between O/N and Sc(III). In addition, a new peak at 529.3eV corresponding to O-Sc bond appears in the spectrum of O1s for Sc(III) loading sample, and the peak area of C-OH significantly decreases. This is because the H atom in the hydroxyl group is replaced by Sc(III) through ion exchange, resulting in the formation of a new coordination bond with O. [ABSTRACT FROM AUTHOR]

Herein, a novel C=O–NOH-contained compound was synthesized and used in the extraction and recovery of copper from sulfate solution. Dodecyl phenyl ethyl hydroxamic acid (DPEHA) exhibited high selectivity to Cu(II) over the competing ions, and the separation factors (β) obtained were βCu/Zn = 227.370, βCu/Co = 199.094, βCu/Ni = 188.889, respectively. The separation effect was stronger than that of 2-hydroxy-5-nonyl acetophenone oxime. Meanwhile, extraction capacity of 0.10 g Cu(II) per gram DPEHA was reached, and the extracted Cu(II) can be stripped effectively. The investigation of extraction mechanism revealed that O atoms in C=O and O-H groups of DPEHA operate as active sites, which could powerfully chelate with Cu(II) by forming stable five-membered rings. The high copper extraction efficiency and selectivity associated with a simple synthesis of DPEHA make it to serve as the potential selective Cu(II) extractant, which also provide a novel insight for the research and development of economical Cu(II) extractants. [ABSTRACT FROM AUTHOR]

The current state of separation technology often neglects the multidimensional nature of real particle systems, which are distributed not only in terms of size, but also in terms of other properties, such as surface charge. Therefore, the aim of this study is to experimentally investigate the applicability of magnetic seeded filtration as a multidimensional separation process. Magnetic seed particles are added to a multisubstance suspension, and a selective heteroagglomeration with the nonmagnetic target particles is induced, allowing for an easy subsequent magnetic separation. The results show that high separation efficiencies can be achieved and that the parameters pH and ionic strength govern the agglomeration process. Selective separation based on surface charge was observed, but undesirable heteroagglomeration processes between the target particles lead to a loss of selectivity. Particle size was clearly identified as a second relevant separation feature, and its partially opposite influence on collision frequency and collision efficiency was discussed. Finally, experimental data of multidimensional separation are presented, in which a size-distributed two-substance suspension is separated into defined size and material fractions in a single process step. This study highlights the need for multidimensional evaluation in general and the potential of magnetic seeded filtration as a promising separation technique. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe/N-BC derived from rape straw was efficient for CIP and Cu2+ adsorption. • Competition for adsorption between CIP and Cu2+ cannot be ignored. • CIP and Cu2+ co-adsorption by Fe/N-BC was a pH-dependent process. • Fe/N-BC could achieve a highly selective CIP/Cu2+ separation from mixed solution. • Fe/N-BC exhibited excellent stability in different water matrixes. The treatment of combined antibiotics and heavy metals pollution is a critical challenge. Herein, iron and nitrogen co-doped biochar (Fe/N-BC) was synthesized using rape straw as precursor, and applied for the adsorption of ciprofloxacin (CIP) and Cu2+ in single and binary systems. The q max for CIP and Cu2+ were 46.45 mg g−1 and 30.77 mg g−1, respectively. Adsorption decreased in a binary matrix, indicating that there was a competitive effect between CIP and Cu2+, which might be due to CIP and Cu2+ sharing similar active adsorption sites on Fe/N-BC. Interestingly, CIP and Cu2+ co-adsorption was a pH-dependent process. Fe/N-BC has potential to highly selectively separate CIP/Cu2+ from mixed solutions through adjusting pH values. Furthermore, adsorption mechanisms were systematically investigated in this research. This research could help to provide a deeper understanding of the synchronously removing specific antibiotics and heavy metals by biochar adsorbents. [ABSTRACT FROM AUTHOR]

Molecularly imprinted membranes (MIMs), the incorporation of a given target molecule into a membrane, are generally used for separating and purifying the effective constituents of various natural products. They have been in use since 1990. The application of MIMs has been studied in many fields, including separation, medicine analysis, solid-phase extraction, and so on, and selective separation is still an active area of research. In MIM separation, two important membrane performances, flux and permselectivities, show a trade-off relationship. The enhancement not only of permselectivity, but also of flux poses a challenging task for membranologists. The present review first describes the recent development of MIMs, as well as various preparation methods, showing the features and applications of MIMs prepared with these different methods. Next, the review focuses on the relationship between flux and permselectivities, providing a detailed analysis of the selective transport mechanisms. According to the majority of the studies in the field, the paramount factors for resolving the trade-off relationship between the permselectivity and the flux in MIMs are the presence of effective high-density recognition sites and a high degree of matching between these sites and the imprinted cavity. Beyond the recognition sites, the membrane structure and pore-size distribution in the final imprinted membrane collectively determine the selective transport mechanism of MIM. Furthermore, it also pointed out that the important parameters of regeneration and antifouling performance have an essential role in MIMs for practical applications. This review subsequently highlights the emerging forms of MIM, including molecularly imprinted nanofiber membranes, new phase-inversion MIMs, and metal–organic-framework-material-based MIMs, as well as the construction of high-density recognition sites for further enhancing the permselectivity/flux. Finally, a discussion of the future of MIMs regarding breakthroughs in solving the flux–permselectivity trade-off is offered. It is believed that there will be greater advancements regarding selective separation using MIMs in the future. [ABSTRACT FROM AUTHOR]

The high concentration of chloride ions in desulphurization wastewater is the primary limiting factor for its reusability. Monovalent anion selective electrodialysis (S-ED) enables the selective removal of chloride ions, thereby facilitating the reuse of desulfurization wastewater. In this study, different concentrations of NaCl and Na2SO4 were used to simulate different softened desulfurization wastewater. The effects of current density and NaCl and Na2SO4 concentration on ion flux, permselectivity (PSO42−Cl−) and specific energy consumption were studied. The results show that Selemion ASA membrane exhibits excellent permselectivity for Cl− and SO42−, with a significantly lower flux observed for SO42− compared to Cl−. Current density exerts a significant influence on ion flux; as the current density increases, the flux of SO42− also increases but at a lower rate than that of Cl−, resulting in an increase in permselectivity. When the current density reaches 25 mA/cm2, the permselectivity reaches a maximum of 50.4. The increase in NaCl concentration leads to a decrease in the SO42− flux; however, the permselectivity is reduced due to the elevated Cl−/SO42− ratio. The SO42− flux increases with the increase in Na2SO4 concentration, while the permselectivity increases with the decrease in Cl−/SO42− ratio.

The water extraction and ethanol precipitation method is an extraction method based on the solubility characteristics of polysaccharides that offers wide applicability in the extraction and separation of plant polysaccharides. However, this method leads to large amounts of proteins, nucleic acids, pigments, and other impurities in the polysaccharides products, which makes downstream purification complicated and time-consuming. In this study, a green, high-density natural deep eutectic solvents was used for the high-purity extraction and separation of polysaccharides from Astragalus membranaceus (Fisch) Bge. var. Mongholicus (Bge.) Hsiao roots under ultrasound-assisted conditions. In this study, 16 different natural deep eutectic solvents were designed to screen the best solvent for extracting Astragalus polysaccharides (APSs). Based on the yield and recovery of APSs, a natural deep eutectic solvents composed of choline chloride and oxalic acid with a molar ratio of 1:2 was selected. The related factors affecting polysaccharides extraction and solvent precipitation were investigated. To improve the operating methodology, single-factor trials, a Plackett-Burman design, and a Box-Behnken design were used. The optimal extraction process conditions were obtained as follows: water content of 55%, liquid–solid ratio of 24 mL/g, ultrasonic irradiation time of 54 min, ultrasonic irradiation temperature of 50 °C, ultrasonic irradiation power of 480 W, ethanol precipitation time of 24 h, and ethanol concentration of 75%. Under optimal extraction conditions, the recovery of APSs was 61.4 ± 0.6 mg/g. Considering the special matrix characteristics of A. membranaceus var. Mongholicus roots, physical-technology-based ultrasonic waves promote penetration, and the mass transfer function also solves the bottleneck of high-viscosity deep eutectic solvents in the extraction stage. In comparison with the conventional method, the proposed method based on deep eutectic solvents isolation can significantly increase APSs recovery, which is beneficial to simplifying the process of polysaccharides purification by using solvent properties to separate extracts and reduce impurities in APSs.

A MXene-based SA-imprinted membrane using cooperative dual-imprinting strategy has been rationally developed to obtain high-selectivity double-layer-based SA-imprinted sites for selective recognition and separation of SA. [Display omitted] Ti 3 C 2 T x (MXene) has attracted extensive attention from scholars at home and abroad due to its rich surface termination functional groups and two-dimensional multilayer structure. In this work, MXene was introduced to the membrane by vacuum-assisted filtration processes, and the formed interlayer channel facilitated the construction of recognition sites and molecular transmission. In this paper, PDA@MXene@PDA@SiO 2 -PVDF dual-imprinted mixed matrix membrane (PMS-DIMs) were developed by the cooperative dual-imprinting strategy, which was used for the adsorption of shikimic acid (SA). Firstly, SiO 2 -PVDF nanofiber basement membrane were prepared by electrospinning method and the first Polydopamine (PDA)-based imprinted layer was constructed on the membrane. PDA not only realized the imprinting process, PDA modification was used to give MXene nanosheets better antioxidant properties and to confer the SiO 2 -PVDF nanofiber membrane the interface stability. After that, the second-imprinted sites were constructed on the stacked MXene nanosheets surface as well as between the layers. The SA dual-imprinted sites significantly increased the efficiency of the selective adsorption efficiency, when the template molecule passed through the membrane, the cooperative dual-imprinting strategy enabled multiplex recognition and adsorption of template molecules. As a consequence, which greatly improving the rebinding ability(262.17 g m−2), and mselectivity factors (β Catechol/SA , β P-HB/SA , β P-NP/SA were 2.34, 4.50 and 5.68). High stability proved the potentials of the PMS-DIMs for practical application. Precise SA-recognition sites were constructed on the PMS-DIMs, PMS-DIMs not only exhibit excellent selective rebinding properties but also have high permeability. [ABSTRACT FROM AUTHOR]

Heavy metal pollution is a key environmental problem. Selectively extracting heavy metals could accomplish water purification and resource recycling simultaneously. Adsorption is a promising approach with a facile process, adaptability for the broad concentration of feed water, and high selectivity. However, the adsorption method faces challenges in synthesizing high-performance sorbents and regenerating adsorbents effectively. FeOOH is an environmentally friendly sorbent with low-cost production on a large scale. Nevertheless, the selectivity behavior and regeneration of FeOOH are seldom studied. Therefore, we investigated the selectivity of FeOOH in a mixed solution of Co2+, Ni2+, and Pb2+ and proposed to enhance the capacity of FeOOH and regenerate it by using external charges. Without charge, the FeOOH electrode shows a Pb2+ uptake capacity of 20 mg/g. After applying a voltage of −0.2/+0.8 V, the uptake capacity increases to a maximum of 42 mg/g and the desorption ratio is 70%–80%. In 35 cycles, FeOOH shows a superior selectivity towards Pb2+ compared with Co2+ and Ni2+, with a purity of 97% ± 3% in the extracts. The high selectivity is attributed to the lower activation energy for Pb2+ sorption. The capacity retentions at the 5th and the 35th cycles are ca. 80% and ca. 50%, respectively, comparable to the chemical regeneration method. With industrially exhausted granular ferric hydroxide as the electrode material, the system exhibits a Pb2+ uptake capacity of 37.4 mg/g with high selectivity. Our work demonstrates the feasibility of regenerating FeOOH by charge and provides a new approach for recycling and upcycling FeOOH sorbent. [ABSTRACT FROM AUTHOR]

High‐performance membranes are critical to membrane separation technology. In recent years, 2D covalent organic frameworks (2D COFs) have attracted extensive attention in the field of membrane separation due to their high porosity, ordered channels, and fine‐tuned pore sizes, which are considered as excellent candidate to solve the trade‐off between membrane selectivity and permeability. Herein, two kinds of ionic 2D COFs with different charge properties (termed as iCOFs) are integrated into polyacrylonitrile (PAN) substrates to form two composite membranes (PAN@iCOFs) with excellent selective perfluoroalkyl substances (PFASs) separation performance with high solvent permeability and good mechanical properties. The as‐prepared PAN@iCOFs composite membranes can selectively reject more than 99.0% of positively and negatively charged PFASs in wastewater while maintaining good stability and recyclability. [ABSTRACT FROM AUTHOR]

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Selective separation of dissolved tungsten and vanadium is of great significance for the utilization of the secondary resources of these elements. In this work, selective removal of vanadium from tungstate solutions via microbubble floating-extraction was systematically investigated. The results indicated that vanadium can be more easily mineralized over tungsten from tungstate solutions using methyl trioctyl ammonium chloride as mineralization reagent under weak alkaline conditions. Owing to the higher bubble and interface mass transfer rates, high-efficiency enrichment and deep separation of vanadium could be achieved easily. Additionally, the deep recovery of tungsten and vanadium from the floated organic phase could be easily realized using a mixed solution of sodium hydroxide and sodium chloride as stripping agents. The separation mechanism mainly included the formation of hydrophobic complexes, their attachment on the surface of rising bubbles, and their mass transfer at the oil-water interface. Under the optimal conditions, the removal efficiency of vanadium reached 98.5% with tungsten loss below 8% after two-stage microbubble floating-extraction. Therefore, the microbubble floating-extraction could be an efficient approach for separating selectively vanadium from tungstate solutions, exhibiting outstanding advantages of high separation efficiency and low consumption of organic solvents. [ABSTRACT FROM AUTHOR]

Long-lived fissiogenic technetium, 99Tc (half-life, 2.11 × 105 yrs), is a byproduct of the 235U and 239Pu fission in nuclear reactors and is a major component in nuclear waste. Hence, the monitoring of 99Tc activity in the environmental samples is essential. Techniques used to measure 99Tc in environmental samples include radiometric and non-radiometric approaches. Inductively coupled plasma mass spectrometry (ICP-MS) has some advantages among the methods due to its high sample throughput, better selectivity, and commercial availability. Rhenium (Re) is often used as the non-isotopic tracer during 99Tc measurement by ICP-MS. From this perspective, studying the separation behavior of Re from the aqueous matrix can provide helpful insight regarding the ecological monitoring of 99Tc. In the current work, three extraction chromatographic resins (ECRs), MetaSEP AnaLig Tc-01, MetaSEP AnaLig Tc-02, and Eichrom TRU, have been used to separate Re from the aqueous matrix. Operating variables, such as solution pH, choice of eluent and eluent concentration, matrix cation effect, and retention capacity, have been studied to optimize the separation protocol. The extraction and recovery behavior of Re was used to interpret the selectivity behavior of the ECRs. The Re separation factor at optimized operating conditions comparing with Mo and Ru (interfering elements during the measurement by ICP-MS) for Meta SEP AnaLig Tc-01, Meta SEP AnaLig Tc-02, and Eichrom TRU resin, respectively, are SFRe/Mo~32, 16.51, and ∞ (metal not retained at all), while SFRe/Ru~∞, 3.25, 5437. In terms of selectivity and retention capacity, MetaSEP AnaLig Tc-01 is the better choice for selective separation of Re, and, assumably so, also Tc, from the aqueous matrices. [ABSTRACT FROM AUTHOR]

In this paper we examined the potential of choline-based deep eutectic solvents (DESs) for selective extraction of tocol homologues from crude palm oil (CPO) through liquid-liquid extraction (LLE). Distribution of tocol homologues (α-tocopherol, α-, β, γ-, and δ-tocotrienol) presence in CPO when subjected to DES-assisted LLE has not been fully understood in the past. The effect of increasing the amount of DES on the distribution and selectivity of were investigated. It was found that tocol homologues were distributed in the order of their hydrophilic power, with tocols of higher polarity distributed more into the stripping phase compared to the less polar tocols. Distribution coefficients for α-tocopherol, α-, β, γ-, and δ-tocotrienol were 7.8, 13.1, 19.8, 22.1 and 29.6, respectively, when equal weight of CPO and choline chloride-malonic acid eutectic mixture (DES1) were used. The distribution of each tocol homologues also increased with increasing DES1, due to the increase in polarity of the stripping phase that attracted more tocols. Selectivity of δ-tocotrienol, which is the most polar tocol, was always higher than other homologues (α-tocopherol: 3.81, α-tocotrienol: 2.22, β-tocotrienol: 1.50, γ-tocotrienol: 1.34). Role of hydrophilic power of the tocols using selected DESs to selectively separate tocol homologues established in this paper has a potential for palm oil industry as tocotrienols are better antioxidants, thus more favorable, than α- tocopherol. [ABSTRACT FROM AUTHOR]

In this study, a new 3D porous PVDF-foam-imprinted membrane (PPIM) for the selective separation of artemisinin (ART) was first prepared via the dopamine adhesion of pre-synthesized MIPs into the interior of the PPIM. In the PPIM, the pre-synthesized molecularly imprinted polymers (MIPs) with artesunate (ARU) as a dummy template were uniformly loaded on the interior of the membrane, avoiding the defects of recognition site encapsulation found in the conventional membrane. This membrane also exhibited excellent flux, which is beneficial in practical separation applications. The PPIM was systematically characterized via FT-IR, SEM, pore-size distribution analysis, water contact angle test, membrane flux, and mechanical performance analysis, respectively. In the static adsorption experiment, the pseudo-second-order kinetic model better fitted the rebinding data of ART. Under dynamic conditions, the ART adsorption capacity of the PPIM could be further remarkably improved by tailoring the flow rate to 3 mL min−1. In the selective separation experiment, with artemether (ARE) as the competition substrate, the selective separation ability (α) of the PPIM towards ART/artemether (ARE) reached its peak value (3.16) within only 10 min at this flow rate, which is higher than that of porous PVDF foam non-imprinted membranes (PPNM) (ca. 1.5), showing great separation efficiency in a short time. Moreover, the PPIM can be reused five times without a significant decrease in its adsorption capacities, showing good regeneration performance. This work highlights a simple strategy for constructing new MIMs with high flux and great mechanical strength to achieve the efficient selective separation of ART and ARE in practical applications.