High Distribution Coefficient Research Articles

A 2D Acridine‐Based Covalent Organic Framework for Selective Detection and Efficient Extraction of Gold from Complex Aqueous‐Based Matrices

AbstractDeveloping candidate materials which possess the ability of both selective detection and efficient capture of precious metal gold is highly desirable for environment and economy. However, most of reported materials only focus on single function, which seriously restricts their practical application as probes or adsorbents. Herein, a two dimensional (2D) acridine‐based covalent organic framework (TpDa‐COF) is prepared via the linkage of imine bonds for gold detection and adsorption. The synthesized COF can achieve both fluorescence and colorimetric dual sensing for Au3+ in a low concentration range (0.1–1.5 ppm) with the limit of detection (LOD) of 0.036 ppm. Impressively, the selectivity of TpDa‐COF for the detection of Au3+ is admirable (Fe3+, Fe2+ and Cu2+ for negligible influence on its fluorescence). In addition, TpDa‐COF exhibits ultrahigh adsorption capacity of 982.5 mg ⋅ g−1 for gold at pH=4, which is attributed the synergistic effect of both selective coordination and reductive process of Au(III) to Au(0). Meanwhile, both positive entropy change (ΔS=76.07 J ⋅ mol−1 ⋅ K−1) and high distribution coefficient (Kd=12484.8 mL ⋅ g−1) confirm the good affinity between TpDa‐COF framework and gold. This work gives us a new insight to prepare COF with pyridine nitrogen sites for gold detection and adsorption.

A 2D Acridine-Based Covalent Organic Framework for Selective Detection and Efficient Extraction of Gold from Complex Aqueous-Based Matrices.

Developing candidate materials which possess the ability of both selective detection and efficient capture of precious metal gold is highly desirable for environment and economy. However, most of reported materials only focus on single function, which seriously restricts their practical application as probes or adsorbents. Herein, a two dimensional (2D) acridine-based covalent organic framework (TpDa-COF) is prepared via the linkage of imine bonds for gold detection and adsorption. The synthesized COF can achieve both fluorescence and colorimetric dual sensing for Au3+ in a low concentration range (0.1-1.5 ppm) with the limit of detection (LOD) of 0.036 ppm. Impressively, the selectivity of TpDa-COF for the detection of Au3+ is admirable (Fe3+, Fe2+ and Cu2+ for negligible influence on its fluorescence). In addition, TpDa-COF exhibits ultrahigh adsorption capacity of 982.5 mg ⋅ g-1 for gold at pH=4, which is attributed the synergistic effect of both selective coordination and reductive process of Au(III) to Au(0). Meanwhile, both positive entropy change (ΔS=76.07 J ⋅ mol-1 ⋅ K-1) and high distribution coefficient (Kd=12484.8 mL ⋅ g-1) confirm the good affinity between TpDa-COF framework and gold. This work gives us a new insight to prepare COF with pyridine nitrogen sites for gold detection and adsorption.

Ultrafast Removal of Thorium and Uranium from Radioactive Waste and Groundwater Using Highly Efficient and Radiation-Resistant Functionalized Triptycene-Based Porous Organic Polymers.

Thorium (Th) and uranium (U) are important strategic resources in nuclear energy-based heavy industries such as energy and defense sectors that also generate significant radioactive waste in the process. The management of nuclear waste is therefore of paramount importance. Contamination of groundwater/surface water by Th/U is increasing at an alarming rate in certain geographical locations. This necessitates the development of strategic adsorbent materials with improved performance for capturing Th/U species from radioactive waste and groundwater. This report describes the design of a unique, robust, and radiation-resistant porous organic polymer (POP: TP-POP-SO3NH4), which demonstrates ultrafast removal of Th(IV) (<30 s)/U(VI) (<60 s) species present in simulated radioactive wastewater/groundwater samples. Thermal, chemical, and radiation stabilities of these POPs were studied in detail. The synthesized ammoniated POP revealed exceptional capture efficiency for trace-level Th (<4 ppb) and U (<3 ppb) metal ions through the cation-exchange mechanism. TP-POP-SO3NH4 shows a significant sorption capacity [Th (787 mg/g) and U (854 mg/g)] with an exceptionally high distribution coefficient (Kd) of 107 mL/g for Th. This work also demonstrates a facile protocol to convert a nonperforming POP, by simple chemical modifications, into a superfast adsorbent for efficient uptake/removal of U/Th.

Recovery of rare earth elements from mine wastewater using alginate microspheres encapsulated with zeolitic imidazolate framework-8

There is increasing demand and interest in efficient methods for the recovery of rare earth elements (REEs) from wastewater because of the growing concerns associated with the negative impacts of REEs-rich waste discharged on pristine ecosystems. Here, we designed a ZIF-8@ALG composite hydrogel by encapsulating zeolitic imidazolate frameworks-8 (ZIF-8) into sodium alginate and poly (vinyl alcohol) double cross-linked networks (ALG) for the recovery of REEs from mine wastewater. ZIF-8@ALG showed exceptional REEs adsorption performance with the most superior separation factor (Ho/Mn) of 597.5. For the REEs considered, the ZIF-8@ALG composite exhibited a preference for heavy REEs with high adsorption efficiencies (65.3 ∼ 97.2%) and distribution coefficients (2045.5 ∼ 28500.0 mL·g−1). Adsorption involved a combination of electrostatic attraction, complexation and ion exchange mechanisms. REEs adsorbed on ZIF-8@ALG could also be desorbed using sodium citrate via ion-exchange and complexation, thus achieving efficient REEs recovery. In addition, ZIF-8@ALG was stable and reusable, maintaining effective adsorption in wastewater over four consecutive cycles, where the optimal adsorption efficiency reached 80.0%. Overall, this study provided an effective and feasible method for the recovery of REEs in mine wastewater, and confirmed that ZIF-8-based materials have significant potential for REEs recovery applications in wastewater engineering treatment.

Record High Iodate Anion Capture by a Redox-Active Cationic Polymer Network.

As a critical radioactive anionic contaminant, traditional adsorbents primarily remove iodate (IO3-) through ion exchange or hard acid-hard base interactions, but suffer from limited affinity and capacity. Herein, employing the synergistic effect of ion exchange and redox, we successfully synthesized a redox-active cationic polymer network (SCU-CPN-6, [C9H10O2N5•Cl]n) by merging guanidino groups with ion-exchange capability and phenolic groups with redox ability via a Schiff base reaction. SCU-CPN-6 exhibits a groundbreaking adsorption capacity of 896 mg/g for IO3-. The inferior adsorption capacities of polymeric networks containing only redox (~0 mg/g) or ion exchange (232 mg/g) fragments underscore the synergistic "1 + 1 > 2" effect of the two mechanisms. Besides, SCU-CPN-6 shows excellent uptake selectivity for IO3- in the presence of high concentrations of SO42-, Cl-, and NO3-. Meanwhile, a high distribution coefficient indicates its exemplary deep-removal performance for low IO3- concentration. The synergic strategy not only presents a breakthrough solution for the efficient removal of IO3- but also establishes a promising avenue for the design of advanced adsorbents for diverse applications.

Record High Iodate Anion Capture by a Redox‐Active Cationic Polymer Network

As a critical radioactive anionic contaminant, traditional adsorbents primarily remove iodate (IO3‐) through ion exchange or hard acid‐hard base interactions, but suffer from limited affinity and capacity. Herein, employing the synergistic effect of ion exchange and redox, we successfully synthesized a redox‐active cationic polymer network (SCU‐CPN‐6, [C9H10O2N5•Cl]n) by merging guanidino groups with ion‐exchange capability and phenolic groups with redox ability via a Schiff base reaction. SCU‐CPN‐6 exhibits a groundbreaking adsorption capacity of 896 mg/g for IO3‐. The inferior adsorption capacities of polymeric networks containing only redox (~0 mg/g) or ion exchange (232 mg/g) fragments underscore the synergistic “1 + 1 &gt; 2” effect of the two mechanisms. Besides, SCU‐CPN‐6 shows excellent uptake selectivity for IO3‐ in the presence of high concentrations of SO42‐, Cl‐, and NO3‐. Meanwhile, a high distribution coefficient indicates its exemplary deep‐removal performance for low IO3‐ concentration. The synergic strategy not only presents a breakthrough solution for the efficient removal of IO3‐ but also establishes a promising avenue for the design of advanced adsorbents for diverse applications.

Microbially formed Mn(IV) oxide as a novel adsorbent for removal of Radium

Radioactivity of Ra isotopes in natural waters is of serious concern. Control of 226Ra concentrations in tailings ponds, which store waste from U ore extraction processes, is an important issue in mill tailings management. In this study, we tested microbially formed Mn(IV) oxide as an adsorbent for removal of Ra in water treatment. Biogenic Mn(IV) oxide (BMO) was prepared using a Mn(II)-oxidizing fungus, Coprinopsis urticicola strain Mn-2. First, adsorption experiments of Sr and Ba, as surrogates for Ra, onto BMO were conducted in aqueous NaCl solution at pH 7. Distribution coefficients for Ba and Sr were estimated to be ∼106.5 and ∼104.3 mL/g, respectively. EXAFS analysis indicated that both Sr and Ba adsorbed in inner-sphere complexes on BMO, suggesting that Ra would adsorb in a similar way. From these findings, we expected that BMO would work effectively in removal of Ra from water. Then, BMO was applied to remove Ra from mine water collected from a U mill tailings pond. Just 7.6 mg of BMO removed >98% of the 226Ra from 3 L of mine water, corresponding to a distribution coefficient of 107.4 mL/g for Ra at pH ∼7. The obtained value was convincingly high for practical application of BMO in water treatment. At the same time, the high distribution coefficient indicates that Mn(IV) oxide can be an important carrier and host phase of Ra in the environment.

ЭКСТРАКЦИЯ ЦЕЗИЯ И СТРОНЦИЯ ИЗ АЗОТНОКИСЛЫХ РАСТВОРОВ КРАУН-ЭФИРАМИ В ТЯЖЕЛЫХ РАЗБАВИТЕЛЯХ

The extraction ability of crown-ethers has been studied with respect to cesium and strontium from nitric acid solutions in heavyweight polar organic solvents: chloroform; 1,2-dichloroethane; bis(2-chloroethyl)ether; nitrobenzene; 1,1,7-trihydrododecafluoroheptyl alcohol. Using bis(2-chloroethyl)ether as a new polar solvent in the extraction processes of dibenzo21-crown-7 and 4,4' (5')-ditretbutyldibenzo-18-crown-6, rather high distribution coefficients of cesium are achieved (DCs) from solutions with a nitric acid concentration of 1-5 mol / dm3. In the extraction of dicyclohexyl-18-crown-6 strontium, the highest DSr values were obtained, using chlorine-substituted hydrocarbons and bis(2-chloroethyl)ether with an extraction maximum of 1-3 mol / dm3 HNO3, depending on the diluent used. Extraction systems based on selective crown-ethers in a solvent mixture for the joint extraction of cesium and strontium from chemically complex nitric acid solutions are proposed.

Surface structure regulating of silica adsorbent for the selective adsorption of heavy rare earth

Rare earth element (REE) is a strategic metal resource, heavy REE owns higher economic and strategic value compared with light rare earth elements. However, it is a great challenge for the separation of heavy rare earth ion efficiently in the solution with mixed rare earth ions due to the similar physicochemical properties of heavy and light REE. In this paper, the diglycolamide (DGA) modified silica adsorbents were prepared and applied to the selective adsorption of heavy earth ion Dy3+. The structure of DGA on the silica surface was regulated during the modifying processes to obtain DGAb-SiO2 and DGAs-SiO2 adsorbent, which was verified by FTIR and NMR characterization results. The adsorption results showed that the DGAb-SiO2 adsorbent owned a much higher distribution coefficient (Kd) value for the selective adsorption of Dy3+ than the DGAs-SiO2 adsorbent. The higher adsorption selectivity is likely due to the fixed carbon chain of the DGA group on the surface of DGAb-SiO2 adsorbent formed rigid spatial structures of the oxygen atoms, which will be favorable for the selective coordination of Dy3+. Besides its effectiveness in adsorption behavior, the DGAb-SiO2 adsorbent displayed excellent stability. The Kd value of DGAb-SiO2 for Dy3+ selective adsorption maintained a high level after four successive recycling runs. The adsorption kinetics results displayed that the adsorption of Dy3+ followed pseudo-second-order kinetic, and the adsorption process fitted the Langmuir isotherm model. Additionally, the same adsorption rules for the rare earth ions were observed over DGA-KIT-6 adsorbent, indicating the high universality of the surface modification to the adsorbent support, which will provide an intentional reference for the surface modification to other adsorbent support.

Nanotrap Grafted Anionic MOF for Superior Uranium Extraction from Seawater.

On-demand uranium extraction from seawater (UES) can mitigate growing sustainable energy needs, while high salinity and low concentration hinder its recovery. A novel anionic metal-organic framework (iMOF-1A) is demonstrated adorned with rare Lewis basic pyrazinic sites as uranyl-specific nanotrap serving as robust ion exchange material for selective uranium extraction, rendering its intrinsic ionic characteristics to minimize leaching. Ionic adsorbents sequestrate 99.8% of the uranium in 120 mins (from 20,000 ppb to 24 ppb) and adsorb large amounts of 1336.8mg g-1 and 625.6mg g-1 from uranium-spiked deionized water and artificial seawater, respectively, with high distribution coefficient, Kd U ≥ 0.97 × 106 mL g-1 . The material offers a very high enrichment index of ≈5754 and it achieves the UES standard of 6.0mg g-1 in 16 days, and harvests 9.42mg g-1 in 30 days from natural seawater. Isothermal titration calorimetry (ITC) studies quantify thermodynamic parameters, previously uncharted in uranium sorption experiments. Infrared nearfield nanospectroscopy (nano-FTIR) and tip-force microscopy (TFM) enable chemical and mechanical elucidation of host-guest interaction at atomic level in sub-micron crystals revealing extant capture events throughout the crystal rather than surface solely. Comprehensive experimentally guided computational studies reveal ultrahigh-selectivity for uranium from seawater, marking mechanistic insight.

Fiber-supported layered magnesium phosphate exhibits high caesium(I) capture capacity in water

Solid-supported adsorbents used for the sequestration of radiocaesium, a major hazardous nuclear fission byproduct, from water are limited by low uptake capacities, increasing the difficulty of radioactive solid waste reduction. This study dispersed potassium magnesium phosphate monohydrate (KMP), a promising Cs+ adsorbent, in polyacrylonitrile fibers (PANFs) to efficiently adsorb Cs+. The larger size of KMP compared to PANFs is conjectured to result in the exposure of some KMP particles, thereby minimizing any decline in their adsorption capacity. The KMP/PANF composite exhibited an adsorption capacity per unit mass of KMP that was nearly equal to that of the bare KMP powder, which was less than 3.52% on average. The composite adsorbent with 100 wt% KMP loading demonstrated the highest experimental capacity of 299 mg g–1 among all solid-supported adsorbents reported to date. It also exhibited relatively fast uptake kinetics (equilibration time = 1.0–4.0 h) and a high distribution coefficient (average value of 1.22 × 104 mL g–1 over pH 5.0–11). Overall, the newly developed KMP/PANF adsorbent exhibits great potential for the practical decontamination of radiocaesium-contaminated waters.

Cross-linked HMO/PVA nanofiber mats for efficient lithium extraction from Salt-lake

With the rapid expansion of the new energy industry and electronics market, the demand for lithium is growing rapidly, leading to a significant increase in the price of the metal. There has been great interest in lithium extraction from salt lakes. The powdered lithium ion-sieve (LIS) suffers from poor dispersion and difficult recovery. Composite polyvinyl alcohol (PVA) nanofiber mats with H1.6Mn1.6O4 (HMO) were prepared by electrostatic spinning and radiation induced cross-linking. HMO was immobilized in the nanofiber mats by covalent attachment, cross-linking and entrapment. Hydrophilicity of PVA, high porosity of nanofiber and cross-linked 3D network endow the HMO/PVA nanofiber mats good mechanical strength, excellent Li+ adsorption performance and long service life. 1/1-HMO/PVA nanofiber mats exhibit Li+ adsorption capacity of 30.1 mg/g in salt-lake brine, which was superior to most LIS-containing adsorbents. Even in real salt-lake water with very low Li concentration of 15.45 mg/L and high Mg/Li ratio of 1260/1, the nanofiber mats have an excellent adsorption capacity of 24.2 mg/g and high distribution coefficient of 9713.34 mL/g, which was close to that of HMO powder. After ten adsorption and elution repetitions Li+ adsorption capacity decreased less than 10%, which indicates the long-term stability of the HMO/PVA nanofiber mats. The loss rate of Mn is less than 5% and gradually decreases with the increase of the number of cycles. The present study demonstrates the potential application of HMO/PVA nanofiber mats for direct recovery of Li+ from salt-lake especially in low-grade high Mg/Li ratio liquid lithium ore where holds a large proportion of the typical salt-lakes in China.

Copper removal and recovery from electroplating effluent with wide pH ranges through hybrid capacitive deionization using CuSe electrode

In modern industry, selective extraction and recovery of Cu from strongly acidic electroplating effluent are crucial to reduce carbon emissions, alleviate resource scarcity, and mitigate water pollution, yielding considerable economic and environmental benefits. This study proposed a high-efficiency CuSe electrode to selectively remove Cu from electroplating effluent via hybrid capacitive deionization (HCDI). The potential of this electrode was thoroughly evaluated to assess its effectiveness. The CuSe electrode exhibited superior deionization performance in terms of Cu adsorption capacity, selectivity, and applicability in various water matrices. Specifically, under strong acid conditions (1 M H+), the CuSe electrode maintained an optimal adsorption capacity of 357.36 mg g−1 toward Cu2+. In systems containing salt ions, heavy metals, and actual electroplating wastewater, the CuSe electrode achieved a remarkable removal efficiency of up to 90% for Cu2+ with a high distribution coefficient Kd. Notably, the capacitive deionization (CDI) system demonstrated the simultaneous removal of Cu-EDTA. The removal mechanism was further revealed using ex-situ X-ray diffraction and X-ray photoelectron spectroscopy analyses. Overall, this study presents a practical approach that extends the capabilities of CDI platforms for effectively removing and recovering Cu from acidic electroplating effluent.

Extraction of C6 α-olefin against n-paraffin in coker naphtha with deep eutectic solvents: Quantum chemical calculations and experimental investigation

Extraction technology is often employed to separate olefin/paraffin mixtures due to the advantages of mature process, flexible operation, and large processing capacity. This work aims to investigate the effectiveness of novel deep eutectic solvents (DESs) for the extraction of 1-hexene/n-hexane model coker naphtha using a combination of simulations and experiments. The results showed that the aliphatic or aromatic groups in the hydrogen bond acceptors or hydrogen bond donors have a strong affinity for 1-hexene, and the components containing hydroxyl or aromatic groups possess the ability to provide protons, which is beneficial to dissolve 1-hexene. Combining the results of the melting point predicted by the group and group-interaction contribution model, three DESs, namely ethanolamine-sulfolane 1:5 (DES1), tetrabutylammonium bromide-bis[2-(2-hydroxyethoxy)ethyl] ether 1:4 (DES2), and methyltriphenylphosphonium bromide-Triethylene glycol 1:4 (DES3), were finally prepared. Then, quantum chemical calculations were used to investigate the separation mechanism between the DESs and 1-hexene/n-hexane, demonstrating single-center and multi-center hybrid weak hydrogen bonds dominated by the dispersion attraction between DESs and 1-hexene. Finally, liquid–liquid equilibrium experiments were used to examine the effects of DESs type, composition, and temperature on the separation performance, and the results showed that the DES1 has both high distribution coefficient of 1-hexene and selectivity of 1-hexene/n-hexane, as well as good recycle stability. This work demonstrates that new DESs can be used as alternative solvents to traditional organic solvents and ionic liquids, and provides ideas for the separation of olefins and paraffins in coker naphtha.

Contamination of groundwater with sulfamethoxazole and antibiotic resistant Escherichia coli in informal settlements in Kisumu, Kenya

High frequency of antibiotic detection in groundwater in informal settlements is attributed to increased usage and improper disposal, thus difficult to identify sources of antibiotic resistance in the environment, worsened by inadequate sanitation facilities and increased population density, particularly in developing-countries. Reliance on groundwater exposes them to pollutants and risk of antibiotic resistance, in addition to experiencing inequities in accessing vital services. Sulfamethoxazole and trimethoprim, used for prophylaxis by HIV/AIDS patients were tested in 49 groundwater sources in Kisumu, Kenya. Only Sulfamethoxazole (SMX) was found, with a detection frequency of 14.3% and concentrations ranging from below limit of quantification (LOQ) to 258.2 ng/L. Trimethoprim (TMP), marketed in combination with sulfamethoxazole, was not detected, owing to its high distribution coefficient (kPa7.12) and, generally, being a bigger molecule with modest water mobility and solubility. Furthermore, TMP ratio in cotrimoxazole is low (5:1), it is expected that mass loading will be lower, as well as influence of the study area’s hydrogeology, where soil is clayey with high porosity and permeability. Escherichia coli was recovered in 98% (n = 48) of water samples, with counts ranging from 16 to 8,850 MPN/100ml. Additionally, resistance to sulfamethoxazole was identified in 6% (n = 3) samples with Inhibition Zone Diameters of 0.8mm(resistant), 10.5mm (resistant), and 11.5mm (intermediate), but not among samples where SMX was detected. Antibiotic concentrations in water that can cause resistance are unknown because antibiotic-resistant E. coli was not found in water samples where sulfamethoxazole was identified, raising concerns about f environmental resistance spread. Concentration of SMX was lower in a previous research, which only collected water from one groundwater source, than the current study, which included additional samples (49). Presence of SMX and Escherichia coli resistance is of concern and necessitates greater attention and regular monitoring for potential contaminants and resistance trigger to avert potential risks to human health.

Bio-inspired functionalization of electrospun nanofibers with anti-biofouling property for efficient uranium extraction from seawater

The development of efficient adsorbents with anti-biofouling properties for uranium extraction from seawater is highly attractive to meet the growing demands for energy. However, traditional fiber adsorbents still suffer from the challenge of weak binding energy, low functional group density, and inefficient antifouling ability. Herein, inspired by the structures of phospholipid, the bio-inspired zwitterionic phosphate groups were created onto the electrospun nanofibers to manipulate the affinity with uranium and the anti-biofouling property. Additionally, hyperbranched grafting reaction together with thin diameters of the fibers were applied to significantly improve the available density of functional groups. The constructed hyperbranched zwitterionic phosphate groups functionalized nanofiber adsorbents (ZP-PAN fibers) exhibited high distribution coefficient kd (7.38 × 106 mL/g) and large adsorption capacity (1294.0 mg g−1) in the uranium-spiked seawater, surpassing most of reported polymeric adsorbents. ZP-PAN fibers also showed good selectivity against competitive cations and stable reusability. Owing to their zwitterionic structures, ZP-PAN fibers had satisfactory anti-adhesive ability toward bacteria and protein. Consequently, the uranium could be effectively extracted by ZP-PAN fibers from natural seawater with the extraction capacity of 8.1 mg g−1 after contacting with seawater for 15 days. This work demonstrates a new functionalization selection for nanofiber materials and provides a promising adsorbent in the practical uranium extraction from seawater.

Separation of butyl acetate and propyl acetate from wastewater by liquid-liquid extraction and molecular dynamics simulation

Pharmaceutical production processes produce ester-containing wastewater, and the concentration of esters must be reduced to a specific limit for wastewater discharge. Therefore, this study investigated a synthetic menthol eutectic solvent to separate the ester-water mixture and meet industrial discharge standards. A deep eutectic solvent (DES) composed of menthol as the hydrogen bond acceptor and lauric acid as the hydrogen bond donor in a molar ratio of 2:1 was synthesized to study the liquid–liquid extraction experiment by separating mixtures of water and propyl acetate (PA) and water and butyl acetate (BA) at 1 atm. In addition, a temperature range of 273.15–318.15 K was used to measure the influence of temperature on the experimental results within a 5 K interval. The experimental results indicated that the increase in temperature promoted the extraction efficiency of ester to some extent, but the fluctuation range was unclear. The DES had a high distribution coefficient (β) and selectivity (S) for ester, enabling a better separation of ester and water. Thereafter, molecular dynamics (MD) simulations were performed to ascertain the mechanism of the DES extraction of esters, and the molecular simulations were used to calculate the interaction energy, radial distribution function (RDF), spatial distribution function (SDF), and self-diffusion coefficient (D). The results of the MD simulations illustrated that menthol played an important role in the extraction process, and the hydrogen bond force between menthol and ester was the main force in the extraction process. Both BA and PA were effectively removed from the water by the DES. In general, the excellent extraction ability of the DES for esters was verified by experiments and simulation, which provides solid theoretical support for ester separations in other fields.

Kaempferol molecularly imprinted polymers: preparation, characterization and application to the separation of kaempferol from ginkgo leaves

AbstractIn this work, kaempferol molecularly imprinted polymers (MIPs) were screened in detail and were applied to the separation of kaempferol from real complex systems. Kaempferol‐MIPs with high affinity and selectivity for kaempferol could be prepared successfully by using kaempferol as the template molecule, 4‐vinylpyridine as the functional monomer, ethylene glycol dimethacrylate or divinylbenzene as the crosslinker, acetone or acetonitrile as the solvent. Scanning electron microscopy observation and Brunauer–Emmett–Teller measurement showed that the prepared MIPs had a heterogeneous pore structure and large specific surface area. Static and dynamic adsorption experiments and solid‐phase extraction application were performed to evaluate the performance of the prepared MIPs. Only the MIPs with both higher distribution coefficient and higher imprinting factor in the dynamic experiments had better ability to retain kaempferol. Using the screened MIPs as solid‐phase extraction sorbents, kaempferol and quercetin were extracted directly from the crude ginkgo leaves hydrolysate with high recovery and purity. Control experiments also showed that the screened MIPs were superior to commercially available adsorbents in terms of the separation of kaempferol from crude extracts. © 2023 Society of Industrial Chemistry.

Separation of n-hexane-ethanol azeotropic mixture using choline chloride +1,4-butanediol deep eutectic solvents

For an environmentally friendly and economical separation process of ethanol from n-hexane which is hard to handle due to the azeotrope, the liquid-liquid extraction was carried out by using choline chloride (ChCl) based deep eutectic solvents (DESs) in different molar ratios with 1,4-butanediol: DES1 (ChCl:1,4-butanediol=1:3), DES2 (ChCl:1,4-butanediol=1:4), and DES3 (ChCl:1,4-butanediol=1:5). The liquid-liquid phase equilibrium was performed on the n-Hexane (1) + Ethanol (2) + DES (3) systems at 298.15 K and atmospheric pressure. The binodal curve is determined by using the turbidity method. The various physico-chemical properties such as refractive index, viscosity, and density were measured for compositions in the binodal point. The equilibrium compositions of liquid-liquid phase equilibrium were determined from the refractive index value at the binodal points, and were predicted by COSMO-SAC model. The miscibility area predicted by COSMO-SAC model became larger as the molar ratio of 1,4-butanediol in DES increased, that is, DES3 shows the most miscible area. While in the experimental results, the miscibility depending on DES-type does not show a large difference. The experimental values for PI shows the order of DES2 (ChCl:1,4-butanediol=1:4)> DES1 (ChCl:1,4-butanediol=1:3)> DES3 (ChCl:1,4-butanediol=1:5) at less 3 wt% concentration of ethanol, but at higher concentration range (>3 wt%) DES3 shows the best value. Both of DES2 and DES3 are profitable to adopt in the extraction process of ethanol from n-hexane owing to the high performance index, high distribution coefficient, and high selectivity. The experimental results show the possibility of DESs as an alternative to ionic liquids in the separation of azeotropic mixtures, taking into account the properties of DES such as low price, uncomplicated manufacturing methods, environmentally friendly, and low toxicity.

Novel class of crown ether functionalized ionic liquids with multiple binding sites for efficient separation of lithium isotopes

Lithium isotopes (6Li, 7Li) separation is an industrially important but challenging process due to their very similar chemical and physical properties. Crown ethers (CEs) have great potential in the isotopes separation for their typical cavity structures. However, the low distribution of Li+ has restricted their industrialuse. In this work, a novel class of functionalized ionic liquids with grafted crown ether-moieties (CE-FILs) for efficient separation of 6Li and 7Li are first reported. The enhanced distribution of Li+ could be achieved by the synergistic effect of ion–dipole interaction, hydrogen bonding and coordination interaction. As a result, an exceptionally high distribution coefficient for Li+ (DLi, up to 136) is obtained using 0.3 M [C6(B15C5)mim][NTf2] with a satisfied separation factor of 1.034 (at 273 K) for 6Li/7Li selectivity from an extremely hydrophilic chloride solutions, which strikes an excellent balance between Li distribution and 6Li/7Li separation. Theoretical calculations and spectroscopic characterization confirm that [C6(B15C5)mim][NTf2] supplies as an ion pair receptor to bind Li+, forming a 1:1 ion-pair complex [C6(B15C5)mim][NTf2]…Li+FeCl4- with double cations and anions. The separation performance of 6Li/7Li mainly depends on the weak interactions associated with Li+. The CE-FILs pave a new way for Li isotopes separation.