Difficulty Of Separation Research Articles

Adsorption of phosphate by ZnCr-LDHs and its zirconium-based hydrogel spheres in water

Phosphate, as one of the main sources of eutrophication problems, has received much attention from researchers in recent years. The process of encapsulating layered double hydroxides (LDHs) in a hydrogel provides an application idea for the removal of phosphate from water by powder materials. LDHs nanomaterials have the advantages of excellent performance, low cost and no secondary pollution, and are limited by application challenges such as low hydraulic conductivity and difficulties in solid-liquid separation. In this study, ZnCr layered double hydroxides (ZnCr-LDHs) were prepared by hydrothermal synthesis using triethanolamine as a base source, and Zr4+ was utilized to prepare spherical hydrogel beads loaded with ZnCr-LDHs sodium alginate. The successful synthesis of ZnCr-LDH materials and Zirconium alginate hydrogel beads encapsulated with ZnCr-LDH was validated through an array of characterization techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The effects of adsorbent dosing, solution pH, adsorption time, initial phosphate concentration, temperature and other anions on phosphate adsorption were investigated. The results showed that under certain experimental conditions (adsorbent dose = 1.0 g/L, initial phosphate concentration = 100 mgP/L, reaction time = 12 h), the composite material could effectively remove phosphate with the maximum adsorption up to 134.95 mgP/g, which effectively solved the solid-liquid separation difficulties of powdered nanomaterials.

Galvanic Interaction between Galena and Pyrite in the Presence of Sodium Lignosulfonate and Its Effects on Flotation.

In the flotation process, there is galvanic corrosion between sulfide mineral particles, which increases the difficulty of separation between minerals. Therefore, the selection of suitable reagents to weaken this corrosion is of great significance. In this article, macromolecular organic reagent sodium lignosulfonate (SLC) was used to weaken the galvanic corrosion between galena and pyrite. Meanwhile, the effect of SLC on the mineral flotation behavior was studied, and the mechanism of SLC was further studied through ion dissolution tests, contact angle tests, infrared spectrum tests, and density functional theory (DFT) calculation. The adsorption of SLC on the mineral electrode increased the charge transfer resistance on the surface of the mineral electrode and hindered the resistance transfer; therefore, it could weaken the galvanic corrosion between galena and pyrite. SLC could selectively depress pyrite at low alkalinity. CaOH+ promoted the adsorption of SLC on the pyrite surface. When the pH of the slurry was adjusted by lime, SLC was more easily adsorbed on the pyrite surface, which hindered the adsorption of the collector on the surface of pyrite.

Progress in carbon capture and impurities removal for high purity hydrogen production from biomass thermochemical conversion

Renewable hydrogen production from biomass thermochemical conversion is an emerging technology to reduce fossil fuel consumptions and carbon emissions. Biomass-derived hydrogen can be produced by pyrolysis, gasification, alkaline thermal treatment, etc. However, the removal of impurities from biomass thermochemical conversion products to improve hydrogen purity is currently technical bottleneck. It is important to assess and investigate the types and properties of impurities, the difficulty of separation, and the impact on downstream utilization of hydrogen in the biomass-derived hydrogen production process. The key objectives of this comprehensive review are: (1) to reveal the current status and necessity of developing biomass-derived hydrogen production; (2) to evaluate the types, devices and impurities distribution of biomass thermochemical conversion; (3) to explore the formation pathways and removal technologies of typical impurities of tar, CO2, sulfides, and nitrides in hydrogen production process; and (4) to propose future insights on the separation technologies of typical impurities to promote the gradual substitution of biomass-derived hydrogen for fossil-derived energy.

Solid–Liquid Phase Equilibria of the Aqueous Quaternary System Rb+, Cs+, Mg2+//SO42− - H2O at T = 323.2 K

Sulfate-type salt lakes constitute over half of the total salt lakes in China and are rich in rare elements, such as rubidium and cesium. However, the complex interactions between ions make the separation and extraction process quite challenging. To address this, phase equilibrium studies were conducted on the sulfate system containing rubidium, cesium, and magnesium. Specifically, the phase equilibria of the aqueous quaternary system Rb+, Cs+, Mg2+//SO42− - H2O at 323.2 K were investigated using the isothermal dissolution method. The solubility, density, and refractive index of the system were experimentally measured. The results indicate that the system at 323.2 K belongs to a complex type with the formation of one solid solution (Rb, Cs)2SO4 and two double salts (Rb2SO4·MgSO4·6H2O, Cs2SO4·MgSO4·6H2O). The corresponding phase diagram consists of four quaternary invariant points, nine univariate curves, and six crystallization regions. Among these, the crystalline region for Cs2SO4·MgSO4·6H2O is the largest, while that for the single salt Cs2SO4 is the smallest. Moreover, the crystalline regions for the double salt and solid solutions are significantly larger than those for the single salt, highlighting the difficulty in separation of valuable single salts. A comparison of multi-temperature phase diagrams from 298.2 K to 323.2 K reveals that the crystalline form of MgSO4 changes from MgSO4·7H2O (298.2 K) to MgSO4·6H2O (323.2 K). As the temperature increases, the phase regions for Rb2SO4, Cs2SO4, (Rb, Cs)2SO4, and Cs2SO4·MgSO4·6H2O expand, while the phase region of Rb2SO4·MgSO4·6H2O contracts, indicating that the single salts (Rb2SO4, Cs2SO4) are more readily precipitated at higher temperature, which provides theoretical guidance for the future production and separation of Rb, Cs, and Mg from sulfate-type salt lakes.

A novel potential of magnetic biochar layered double-hydroxide hybrid to enhance enzyme performance

Magnetic biochar (MBC) is a popular choice for enzyme immobilization, due to its large surface area and compatibility with a range of substances. Nonetheless, its small particle size poses difficulties in separation after the adsorption process. To overcome this challenge, the current study introduces an innovative nano-hybrid material that integrates MBC with MgFe-layered double hydroxides (MgFe-LDH) for enzyme immobilization. This hybrid aims to facilitate easier separation while preserving the advantageous properties of MBC in enzyme immobilization. FT-IR, SEM, XRD, and EDS analyses indicated the successful loading of MgFe-LDH onto magnetic biochar through hydrothermal synthesis. Protamex®, a blend of microbial endo-proteases, exhibited a high affinity for absorbing the LDHs nanohybrid surface, thus confirming that the presence of magnetic biochar in the core structure of MBC/MgFe-LDH effectively dispersed the nanohybrid. Furthermore, the magnetic LDH enabled immobilized enzyme recovery via magnetic interaction. The free Protamex® showed a decrease in approximately 45% of its initial activity within 120 days. This activity loss for the immobilized enzyme on the magnetic biohybrid was only about 25%.

Aerodynamic study of a leading-edge rotating cylinder in a cambered aerofoil (NACA2412)

PurposeFlow separation over an aircraft’s wing beyond a specific angle of attack is challenging. Flow boundary layer manipulation has been investigated to improve aerofoil lift and mitigate flow separation difficulties including stall and drag. This is solved via active or passive flow control. Active flow control method moving surface boundary (MSB) enhances shear flow momentum, making it effective. MSB is easier than suction and blowing. Asymmetrical airfoils, which generate lift in aircraft wings, have received less MSB research than symmetrical ones. The purpose of this study is to asses the design efficacy of MSB’s NACA 2412 aerofoil.Design/methodology/approachTo observe the performance of MSB in NACA 2412, a computational model has been created, and aerodynamical performance has been analyzed.FindingsThe study results show that the NACA 2412 with MSB has better aerodynamic efficiency than the NACA 2412 base design. It works best when it reaches its optimal speed and the delay in flow separation works well.Research limitations/implicationsLimitations may include specific aerofoil applicability, external factors and simulation constraints. Implications guide future research for broader insights and applications.Practical implicationsImproving asymmetrical aerofoil performance, mitigating stall effects, reducing drag and optimizing designs with moving surface boundary. Insights gained can enhance overall aircraft efficiency and flow control techniques.Originality/valueThe MSB flow control in a chambered aerofoil is less explored and not explored enough in wing-based aerofoils, and the optimal cylinder speed ratio trend has been discussed at each angle of attack studied.

Clay Minerals/TiO2 Composites—Characterization and Application in Photocatalytic Degradation of Water Pollutants

TiO2 used for photocatalytic water purification is most active in the form of nanoparticles (NP), but their use is fraught with difficulties in separation from solution or/and a tendency to agglomerate. The novel materials designed in this work circumvent these problems by immobilizing TiO2 NPs on the surface of exfoliated clay minerals. A series of TiO2/clay mineral composites were obtained using five different clay components: the Na-, CTA-, or H-form of montmorillonite (Mt) and Na- or CTA-form of laponite (Lap). The TiO2 component was prepared using the inverse microemulsion method. The composites were characterized with X-ray diffraction, scanning/transmission electron microscopy/energy dispersive X-ray spectroscopy, FTIR spectroscopy, thermal analysis, and N2 adsorption–desorption isotherms. It was shown that upon composite synthesis, the Mt interlayer became filled by a mixture of CTA+ and hydronium ions, regardless of the nature of the parent clay, while the structure of Lap underwent partial destruction. The composites displayed high specific surface area and uniform mesoporosity determined by the size of the TiO2 nanoparticles. The best textural parameters were shown by composites containing clay components whose structure was partially destroyed; for instance, Ti/CTA-Lap had a specific surface area of 420 m2g−1 and a pore volume of 0.653 cm3g−1. The materials were tested in the photodegradation of methyl orange and humic acid upon UV irradiation. The photocatalytic activity could be correlated with the development of textural properties. In both reactions, the performance of the most photoactive composites surpassed that of the reference commercial P25 titania.

On the greenness of separation modes containing compressed fluids

BackgroundIn the past three decades, liquid chromatography (LC) has been recognized as a significant environmental, health, and safety burden due to its heavy reliance on toxic organic solvents. Various chromatographic modes are in vogue today for complex analyses, such as sub/supercritical fluid chromatography (SFC) and enhanced fluidity liquid chromatography (EFLC). These modes are often advertised as "universally green" compared to the traditional allliquid reversed (RPLC) and normal phases (NPLC). Quantitative greenness evaluations must be done to validate or invalidate this assumption and allow separation scientists to make educated choices when deciding on what mode to use. ResultsIn this work, we modify the Analytical Method Greenness Score (AMGS) to include the cycle time of the instrument, and with the help of the first-order optimality condition (by setting the AMGS gradient = 0), we show that SFC and EFLC are not always the greenest option as they are often thought to be. Most of the greenness metrics have ignored the cycle time of instruments, yet this key component changes the entire AMGS response to flow rate. The complex case of separating tobacco alkaloid enantiomers (nicotine, nornicotine, anabasine, and anatabine) was selected as an illustrative example for comparing and contrasting separation modes using the modified greenness metric. These enantiomers have been selected due to their notorious difficulty in separation over the past 30 years. Using this family of molecules, four unique retention patterns were observed covering a wide variety of retention phenomena seen in small molecule enantioseparations. SignificanceThe modified AMGS metric will assist practicing analytical chemists in assessing the environmental impact of their separation methods from a single run in a given chromatographic mode. The proposed methodology identifies the minimum AMGS score corresponding to the greenest separation for routine chemical analysis.

Composition Dependence of Flow-Induced Crystallization in High-Density Polyethylene/Isotactic Polypropylene Blends.

Polyolefins, including high-density polyethylene (HDPE) and isotactic polypropylene (iPP), account for over half of the worldwide plastics market and have wide-ranging applications. Recycling of these materials is hindered due to separation difficulties as co-mingled blends of HDPE and iPP often exhibit brittle mechanical behavior because phase separated domains detach under stress due to low interfacial adhesion. Motivated to improve mechanical properties of mixed recyclates during processing, this work examines the effect of shear on the crystallization kinetics and rheological properties of HDPE-iPP blends utilizing a combination of differential scanning calorimetry (DSC), rheo-Raman spectroscopy, polarized optical microscopy, and scanning electron microscopy (SEM). In the quiescent experiments, the crystallization temperature as a function of blend composition exhibits a distinct decrease when the iPP forms the droplet phase, as expected, due to fractionated crystallization. In the presence of shear, we find elongated domains due to high capillary number. Unexpectedly, we find a compositional dependence to the flow-induced crystallization (FIC) of iPP: stronger FIC is observed in all blends compared to the pure iPP. Moreover, the flow completely counteracts the reduced crystallization arising from fractionated crystallization, indicating that the flow is able to induce nucleation in droplets to an extent such that it offsets the reduction in active nucleating agents in finite size droplets. We attribute these effects to differing microflow fields in the various morphologies as the iPP domains deform under shear.

The first detection of the poplar bark aphid, Pterocomma populeum (Hemiptera: Aphididae), in Australia

AbstractPterocomma (Hemiptera: Aphidinae) are large aphids found across the northern hemisphere on various willow (Salix) and poplar (Populus) trees. We provide the first records of the Poplar Bark Aphid, Pterocomma populeum in Australia from Tasmania and New South Wales, a potential pest of poplar trees. Morphological character measurements and DNA (cytochrome oxidase subunit 1) sequences are provided along with discussions around difficulties in species separation.

A photocatalysis-self-Fenton system based on NCDs@ZnIn2S4 composites at neutral pH and low amount of Fe2+ for the effective degradation of antibiotics

Photocatalysis-self-Fenton combining photocatalytic production of H2O2 with Fenton reaction has been a hotspot, but the pH limitation and iron sludge production problems remain unsolved. Herein, we proposed a self-fenton system based on N-doped carbon dots modified ZnIn2S4 (NCDs@ZnIn2S4) composites that exhibits effective degradation of antibiotics under neutral pH using low amounts of Fe2+. The decoration of ZnIn2S4 with NCDs significantly increased the surface area, visible light absorption, charge transfer ability and oxygen adsorption ability. NCDs@ZnIn2S4 composites exhibited a high H2O2 production rate (1528 μM g−1•h−1) under visible light, which was 1.9 and 5.3 times higher than ZnIn2S4 and NCDs, respectively. Meanwhile, the Fe2+/NCDs@ZnIn2S4 system with a low concentration of Fe2+(1 mg/L) could remove over 95% levofloxacin and oxytetracycline within 30 min. Interestingly, the highest degradation efficiency occurred under neutral pH. Quenching experiments and analytical measurements indicated that the high catalytic performance under pH = 7 with low amounts of Fe2+ stemmed from the higher amount of inner-generate H2O2 under neutral pH and easy regeneration of Fe2+ by photoinduced electrons for high •OH yields. Additionally, the Fe2+/NCDs@ZnIn2S4 system exhibited high degradation performance under different water matrix and ultrahigh degradation efficiency towards levofloxacin under real sunlight irradiation. The work shows the prospects of photocatalysis-self-Fenton systems for overcoming the pH limitation and the difficulty of iron sludge separation in the purification of effluents.

NiFe2O4 magnetic nanoparticles supported on MIL-101(Fe) as bimetallic adsorbent for boosted capture ability toward levofloxacin

Levofloxacin (LVX) capture with microcrystalline particles of monometallic metal-organic frameworks (MOFs) is definitely restricted and challenged by its difficulties in solid-liquid separation and enhanced of adsorption capacity issues. Meanwhile, the development of magnetic MOFs with excellent adsorption capabilities and outstanding recyclability is crucial. Herein, a novel magnetic Fe/Ni bimetal MOFs composite (MIL-101(Fe)@NiFe2O4, MNFO) for LVX capture has been effectively fabricated for LVX capture, utilizing MIL-101(Fe) as the primary adsorbent and NiFe2O4 nanoparticles as the magnetic element. Attributed to the synergistic ability of bimetal ions (Fe2+ and Ni2+), MNFO exhibits a significant adsorption capacity (335 mg/g) and rapid adsorption rate (10 min) towards LVX. The adsorption capacity indicates an increasing-then-decreasing trend with an increase of the pH values. Additionally, the adsorption data are well fitted by the Freundlich and pseudo-second-order kinetic models. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. In addition, the adsorbent demonstrated excellent reusability, as it could be readily recovered from the liquid phase through the magnetic properties of NiFe2O4. Remarkably, it retained approximately 90 % of its adsorption capacity of the uptakes after 5 cycles. This study offers a innovative approach to the development of highly efficient adsorbents for capturing LVX from water.

Pyrolysis-gas chromatography/mass spectrometry analysis as a useful tool in identifying fibre composition in mixed post-consumer textile waste

The progress of textile recycling is significantly impeded by the absence of adequate methodologies for determining the composition of fibres in textile blends. The examination of textile mixtures poses considerable difficulties, particularly due to the presence of elastane fibres, which in their limited quantities cannot be easily detected using conventional analytical techniques. Further, the undetected elastane fibres pose difficulty in separation during recycling of the textiles as they end up as impurities in cases where dissolution of the fibres is employed. Consequently, it is of utmost importance to explore new analytical tools that possess the capability to identify the primary fibres in post-consumer waste. In the current investigation, we conducted a study to assess the capabilities of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Pyrolysis coupled with Gas Chromatography and Mass Spectrometry (Py-GC/MS) for the characterization of postconsumer textile fabrics. A comprehensive pyrolysis database was established encompassing prevalent pure fibres commonly employed in textile production. In addition, an examination was conducted on three textile blends with predetermined compositions, and the findings were subsequently compared with data obtained through the utilization of ATR-FTIR. The data derived from the original fibres was ultimately utilized for the examination of post-consumer fabric samples acquired from a waste landfill. The utilization of Py-GC/MS, scanning electron microscopy (SEM) and ATR-FTIR enabled to discern fibre compositions of mixtures even those that contained relatively low fibre content.

Flow characteristics and mass transfer performance of phosphoric acid extraction in a T-type central plug-in microreactor

In recent years, the demand for phosphoric acid, a key raw material for lithium iron phosphate batteries, has surged. However, current phosphoric acid extraction equipment faces challenges such as low mass transfer efficiency and difficulty in phase separation, leading to reduced production efficiency, bulky equipment, and scaling issues. To address these problems, this study introduces a T-type central plug-in microreactor (TCPM) designed to enhance mass transfer efficiency and facilitate rapid phase separation. The extraction of phosphoric acid from the water phase to the organic phase (volume ratio of tributyl phosphate to kerosene is 4:1) was chosen as the experimental system. We investigated the effects of various parameters on liquid-liquid flow and mass transfer characteristics in the TCPM. Visualization techniques identified slug and parallel flow as the primary liquid-liquid flow patterns within the TCPM. Notably, the central plug-in promotes the formation of parallel flow, improving phase separation compared to conventional T-type microreactors. The volume mass transfer coefficient of the TCPM ranges from 0.023 to 0.074 s-1, and the optimal phosphoric acid extraction efficiency and volume mass transfer coefficient can reach up to 90.5% and 0.074 s-1, respectively, outperforming conventional T-type microreactors. Predictive model for extraction efficiency was developed, showing deviations within 10%. These findings demonstrate the TCPM's potential as an efficient phosphoric acid extraction device with rapid phase separation, holding significant promise for liquid-liquid extraction applications.

Fabrication and application of magnetic MgFe2O4-OH@biochar composites decorated with β-ketoenamine for Pb(II) and Cd(II) adsorption and immobilization from aqueous solution

The excessive discharge of water contaminated by lead (Pb(II)) and cadmium (Cd(II)) seriously jeopardizes ecological security and needs to be addressed urgently. Herein, a novel, efficient and highly stable biochar-based magnetic adsorbent of KEA-MgFe2O4-OH@RSBC was fabricated via loading MgFe2O4-OH nanoparticles (NPs) on reed straw biochar (RSBC) surface followed by decorating with β-ketoenamine (KEA) to boost the capture efficiency of Pb(II)/Cd(II) from wastewater. Adsorption behavior and mechanism studies indicated that the abundant and diverse functional groups of KEA-MgFe2O4-OH@RSBC were favorable for Pb(II)/Cd(II) removal. The binding of KEA-MgFe2O4-OH@RSBC with Pb(II)/Cd(II) was increased mainly via complexation, electrostatic attraction, cation-π coordination, ion exchange and pore filling. Due to the incorporation of MgFe2O4-OH and KEA, the Pb(II) /Cd(II) uptake capacity by KEA-MgFe2O4-OH@RSBC reached up to 238.06/226.76 mg/g (pH=5.0, C0 = 180 mg/L). The XPS analysis showcased that the strong interactions between Pb(II)/Cd(II) and oxygen/nitrogen atoms in the composites played an important role for the adsorption of Pb(II)/Cd(II) by KEA-MgFe2O4-OH@RSBC. In addition, the evaluation study on the practical application potential of KEA-MgFe2O4-OH@RSBC manifested that the material exhibited strong resistance to ionic interference (R> 93 % in collected actual metal smelting wastewater). KEA-MgFe2O4-OH@RSBC had a good regeneration and reapplication capability (R> 82 % after 5 cyclic regeneration experiments). Besides, the stronger magnetism overcome the separation difficulty after adsorption from wastewater. In conclusion, KEA-MgFe2O4-OH@RSBC will be an ideal candidate for Pb(II)/Cd(II) removal from contaminated water systems. The present study would greatly contribute to the effective and sustainable progress of heavy metal remediation strategies.

Investigation into the impact of Mn2+ and its interaction with calcite in the flotation of rhodochrosite

The unavoidable Mn2+ ions in pulp were considered in the flotation of rhodochrosite, and its effect and relative interaction mechanism on the floatability of calcite served as a typical gangue mineral were investigated through microflotation tests, zeta potential measurements, SEM-EDS detection, solution chemistry calculation, adsorption experiments, FTIR and XPS analyses. There exhibited a good separation performance of rhodochrosite against calcite with OHA collector, but in the presence of Mn2+ ions, the floatability of calcite was closed to rhodochrosite within a pH of 8.0–10.0, which resulted in the separation difficulty between them. As evidenced, the surface of calcite could be modified by Mn2+ ions, its isoelectric point shifted positively from 8.91 to 10.06, and Mn2+ species detected on calcite surfaces were in close proximity to rhodochrosite. It indicated that MnCO3 precipitates were generated on the surface of calcite. After modified by Mn2+, the calcite surface became more active and obviously increased the adsorption amount of OHA. It was verified from zeta potential and XPS analyses that Mn species on the surface of calcite were active sites for OHA adsorption, likely the hydroxamate group of OHA collector chelated with Mn species to form hydrophobic compounds. As a result, Mn2+ ions in pulp would reduce the flotation selectivity of rhodochrosite from calcite, thus it is necessary to eliminate the disadvantage of Mn2+ for strengthening flotation.

TFLN-based nondegenerate optical parametric amplifier with high gain, high saturated optical power and linear wavelength tunability

Optical parametric amplifier (OPA) utilizing thin-film lithium niobate (TFLN) is a cornerstone in integrated microwave optics and high-speed optical communication due to its outstanding properties, including high gain, low noise figure, and high integration. Here, we proposed a pump-depletion nondegenerate amplifier to discuss the saturated optical power. This OPA exhibits a good performance with high gain (over 30 dB) and high saturated optical power (over 15 dBm). The signal frequency is well separated from idle which reduces the difficulties of separation. Meanwhile, we found that the quasi-phase-matching wavelength can be regulated by temperature to achieve a linear adjustable OPA. Detailed design strategies are provided in this paper to underpin the fabrication of high-performance OPA in integrated optics. This theoretical analysis creates opportunities for performance enhancement in microwave photonic links.

Emerging Nanomaterials as Versatile Nanozymes: A New Dimension in Biomedical Research.

The enzyme-mimicking nature of versatile nanomaterials proposes a new class of materials categorized as nano-enzymes, ornanozymes. They are artificial enzymes fabricated by functionalizing nanomaterials to generate active sites that can mimic enzyme-like functions. Materials extend from metals and oxides to inorganic nanoparticles possessing intrinsic enzyme-like properties. High cost, low stability, difficulty in separation, reusability, and storage issues of natural enzymes can be well addressed by nanozymes. Since 2007, more than 100 nanozymes have been reported that mimic enzymes like peroxidase, oxidase, catalase, protease, nuclease, hydrolase, superoxide dismutase, etc. In addition, several nanozymes can also exhibit multi-enzyme properties. Vast applications have been reported by exploiting the chemical, optical, and physiochemical properties offered by nanozymes. This review focuses on the reported nanozymes fabricated from a variety of materials along with their enzyme-mimicking activity involving tuning of materials such as metal nanoparticles (NPs), metal-oxide NPs, metal-organic framework (MOF), covalent organic framework (COF), and carbon-based NPs. Furthermore, diverse applications of nanozymes in biomedical research are discussed in detail.

Soft and diffusion-controlled Sr-MOF for efficient separation of H2O/D2O

Heavy water (D2O) electrolysis is the primary technology for D2 production, playing an irreplaceable role in fields such as nuclear fusion research and isotope tracing. However, the inherent similarity in chemical properties between H2O and D2O (with only a 1.4 °C difference in boiling points) poses significant challenges to their separation. Furthermore, the extremely low natural abundance of D2O (0.015 %) increases the difficulty and cost of separation, while traditional electrolysis and distillation techniques are highly energy intensive. Therefore, there is an urgent need to develop novel adsorbents for efficient and environmentally sustainable H2O/D2O separation. Herein, we used polydentate ligand 2, 5-dihydroxyterephthalic acid (DOBDC) and its derivatives 4,4́-(anthracene-9,10-diyl) bis (2-hydroxybenzoic acid (ABHB) as raw materials to prepare two novel high coordination Sr-MOFs namely IPE-1 and IPE-2, respectively. These MOFs were applied for efficient separation of H2O and D2O at room temperature. X-ray diffraction results reveal that one Sr atom in IPE-1 is coordinated with 9 oxygen atoms. This high coordination number results in the formation of ultra-small rectangular pores of approximately 2.5 Å. Adsorption isotherms of N2, CO2, H2O, and D2O indicate that the ultramicroporous structure of IPE-1 precludes efficient diffusion of CO2 and H2O molecules into the MOF channels. In contrast, the activated IPE-2 exhibits good CO2, H2O, and D2O uptake capacities of 3 mmol/g, 8.38 mmol/g, and 6.51 mmol/g at 298 K, respectively. The Qst values and Ksap values of H2O and D2O indicate that the adsorption rates of H2O were much higher than D2O under 0.2 < P/P0 < 0.7, with a calculated ratio of approximately 1.26. This study not only provides appealing MOFs materials for efficient H2O/D2O separation at room temperature but also provides a new avenue for preparing adsorbents with high stability and high separation performance.

Tetraphenylborate enhanced enzymatic production of γ-cyclodextrin: System construction and its mechanism

γ-Cyclodextrin (γ-CD) is an attractive material among the natural cyclodextrins owing to its excellent properties. γ-CD is primarily produced from starch by γ-cyclodextrin glycosyltransferase (γ-CGTase) in a controlled system. However, difficulty in separation and low conversion rate leads to high production costs for γ-CD. In this study, γ-CGTase from Bacillus sp. G-825-6 STB17 was used in γ-CD production from cassava starch. With the introduction of sodium tetraphenylborate (NaBPh4), the total conversion rate was promoted from an initial 18.07 % to 50.49 % and the γ-CD ratio reached 78.81 % with a yield of 39.79 g/L. Furthermore, the mechanism was conducted via the determination of binding constant, which indicated that γ-CD exhibited much stronger binding strength with NaBPh4 than β-CD. The reformation of water molecules and the chaotropic effect might be the main driving forces for the interaction. Additionally, the conformations of CD complexes were depicted by NMR and molecular docking. The results further verified different binding patterns between CDs and tetraphenylborate ions, which might be the primary reason for the specific binding. This system not only guides γ-CD production with an efficient and easy-to-remove production aid but also offers a new perspective on the selection of complexing agents in CD production.