Deep eutectic solvents for separation and purification applications in critical metal metallurgy:Recent advances and perspectives

Solvent extraction,a separation and purification technology,is crucial in critical metal metallurgy.Organic solvents commonly used in solvent extraction exhibit disadvantages,such as high volatility,high toxicity,and flammability,causing a spectrum of hazards to human health and environmental safety.Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents.In the past two decades,several neoteric solvents have been proposed,including ionic liquids(ILs)and deep eutectic solvents(DESs).DESs have gradually become the focus of green solvents owing to several advantages,namely,low toxicity,degradability,and low cost.In this critical review,their classification,formation mechanisms,preparation methods,characterization technologies,and special physicochemical properties based on the most recent advancements in research have been systematically described.Subsequently,the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized.Finally,future opportunities and challenges of DESs were explored in the current research area.In conclusion,this review provides valuable insights for improving our overall understanding of DESs,and it holds important potential for expanding separation and purification applications in critical metal metallurgy.

Effects of ultrasonic-assisted extraction on bioactive compounds,volatile flavors and antioxidant activities of vine tea water extracts

Background:Ampelopsis grossedentata,vine tea,which is the tea alternative beverages in China.In vine tea processing,a large amount of broken tea is produced,which has low commercial value.Methods:This study investigates the influence of different extraction methods(room temperature water extraction,boiling water extraction,ultrasonic-assisted room temperature water extraction,and ultrasonic-assisted boiling water extraction,referred to as room temperature water extraction(RE),boiling water extraction(BE),ultrasonic assistance at room temperature water extraction(URE),and ultrasonic assistance in boiling water extraction(UBE))on the yield,dihydromyricetin(DMY)content,free amino acid composition,volatile aroma components,and antioxidant properties of vine tea extracts.Results:A notable influence of extraction temperature on the yield of vine tea extracts(P<0.05),with BE yielding the highest at 43.13±0.26%,higher than that of RE(34.29±0.81%).Ultrasound-assisted extraction significantly increased the DMY content of the extracts(P<0.05),whereas DMY content in the RE extracts was 59.94±1.70%,that of URE reached 66.14±2.78%.Analysis revealed 17 amino acids,with L-serine and aspartic acid being the most abundant in the extracts,nevertheless ultrasound-assisted extraction reduced total free amino acid content.Gas chromatography-mass spectrometry analysis demonstrated an increase in the diversity and quantity of compounds in the vine tea water extracts obtained through ultrasonic-assisted extraction.Specifically,69 and 68 volatile compounds were found in URE and UBE extracts,which were higher than the number found in RE and BE extracts.In vitro,antioxidant activity assessments revealed varying antioxidant capacities among different extraction methods,with RE exhibiting the highest DPPH scavenging rate,URE leading in ABTS•+free radical scavenging,and BE demonstrating superior ferric ion reducing antioxidant activity.Conclusion:The findings suggest that extraction methods significantly influence the chemical composition and antioxidant properties of vine tea extracts.Ultrasonic-assisted extraction proved instrumental in elevating the DMY content in vine tea extracts,thereby enriching its flavor profile while maintaining its antioxidant properties.

Synergistic extraction and separation of valuable elements from high-alumina fly ash with carbochlorination method

A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to conduct carbochlorination of the fly ash within the temperature range from 700 to 1000℃.The experimental results demonstrated that under the optimal conditions,the carbochlorination efficiency for Al,Si,Ca,Ti,and Mg exceeded 81.18%,67.62%,58.87%,82.15%,and 59.53%,respectively.The XRD patterns indicated that Al and Si in the mullite phase(Al_(6)Si_(2)O_(13))were chlorinated during the carbochlorination process,resulting in the formation of mullite mesophases(Al_(4.75)Si_(1.25)O_(9.63) and Al_(1.83)Si_(1.08)O_(4.85)).After the carbochlorination process,Al was accumulated as AlCl_(3) in the condenser,while SiCl_(4) and TiCl_(4) were enriched in the exhaust gas,and CaCl_(2),MgCl_(2),and unreacted oxides remained in the residue for further recycling.

Direct capture and separation of CO_(2) from air

Direct air capture(DAC)has attracted increasing interest and investment over the past few years.There are a fast-growing number of companies that entered the field and demonstrated DAC carbon removal setups and potential.However,current DAC methods are still based on solid absorbents or alkali solutions approaches which have low capture efficiency and low energy efficiency.This highlight proposed a promising CO_(2) capture technology,an electric energy driven closed-loop system for the direct removal of CO_(2) from ambient air which are based on two individual technologies:Polyam-N-Cu hybrid system promoted CO_(2) capture with ocean as anthropogenic CO_(2) sink and a chloride-mediated electrochemical pH swing system to remove CO_(2) from oceanwater.

A Review on Sources,Extractions and Analysis Methods of a Sustainable Biomaterial:Tannins

Condensed and hydrolysable tannins are non-toxic natural polyphenols that are a commercial commodity industrialized for tanning hides to obtain leather and for a growing number of other industrial applications mainly to substitute petroleum-based products.They are a definite class of sustainable materials of the forestry industry.They have been in operation for hundreds of years to manufacture leather and now for a growing number of applications in a variety of other industries,such as wood adhesives,metal coating,pharmaceutical/medical applications and several others.This review presents the main sources,either already or potentially commercial of this forestry by-materials,their industrial and laboratory extraction systems,their systems of analysis with their advantages and drawbacks,be these methods so simple to even appear primitive but nonetheless of proven effectiveness,or very modern and instrumental.It constitutes a basic but essential summary of what is necessary to know of these sustainable materials.In doing so,the review highlights some of the main challenges that remain to be addressed to deliver the quality and economics of tannin supply necessary to fulfill the industrial production requirements for some materials-based uses.

Selective separation of Cu(Ⅱ),Zn(Ⅱ),and Cd(Ⅱ)by solvent extraction

An experimental investigation was presented on the separation of Cu（Ⅱ）, Zn（Ⅱ）, and Cd（Ⅱ） from a rich sulfate leachate of zinc slag by solvent extraction. The results of orthogonal experiments indicate that LIX 984N is highly selective and very efficient in the extraction of Cu（Ⅱ）, and the analysis of variance indicates that the sequence of parameters according to their influence on the separation efficiency is phase ratio 〉 LIX 984N concentration 〉 pH value 〉 extraction time. The optimal condition for copper extraction is obtained as 25% of LIX 984N concentration, 7 rain of extraction time, 3：2 of phase ratio O/A, and pH = 1.7. The separation of Zn（Ⅱ） and Cd（Ⅱ） was performed after the copper extraction from the raffinate. Comparative analysis of the separation with di-2-ethylhexyl phosphoric acid （D2EHPA）, D2EHPA-tributyl- phosophate （TBP） synergistic extracting system, and 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester （HEHEHP） was made at pH = 2.0. It is demonstrated that the extraction efficiency with D2EHPA is improved after being saponified by sodium hydroxide, and D2EHPA-TBP synergistic extracting, as well as HEHEHP, has a superior selectivity to Zn（Ⅱ） over Cd（Ⅱ）.

Phase separation and transcriptional regulation in cancer development

Liquid-liquid phase separation,a novel biochemical phenomenon,has been increasingly studied for its medical applications.It underlies the formation of membrane-less organelles and is involved in many cellular and biological processes.During transcriptional regulation,dynamic condensates are formed through interactions between transcriptional elements,such as transcription factors,coactivators,and mediators.Cancer is a disease characterized by uncontrolled cell proliferation,but the precise mechanisms underlying tumorigenesis often remain to be elucidated.Emerging evidence has linked abnormal transcriptional condensates to several diseases,especially cancer,implying that phase separation plays an important role in tumorigenesis.Condensates formed by phase separation may have an effect on gene transcription in tumors.In the present review,we focus on the correlation between phase separation and transcriptional regulation,as well as how this phenomenon contributes to cancer development.

Equilibrium and kinetic data of adsorption and separation for zirconium and hafnium onto MIBK extraction resin

The equilibrium and kinetics of methyl isobutyl ketone(MIBK) extraction resin for adsorption and separation of zirconium and hafnium were studied under the different conditions of acidity,initial total concentrations of zirconium and hafnium and temperature.The equilibrium data of both zirconium and hafnium are found to follow the Freundlich adsorption isotherm,and the Freundlich isotherm constants(KF) are 3.53 and 0.64 mg/g,respectively.The equilibrium data of zirconium also fit the Langmuir adsorption isotherm,and the saturation adsorption capacity(Qmax) and the Langmuir isotherm constant(KL)are 75.93 mg/g and-0.012 7 L/g,respectively.The obtained kinetic data of both zirconium and hafnium are found to fit the HO pseudo-second-order kinetic model,and the rate constants of pseudo-second-order equation(k2) are-0.019 and 0.41 g/(mg·min),respectively.Column tests show that the MIBK extraction resin could be used as efficient adsorbent material for separating hafnium from zirconium.

Separation of Red (Y_2O_3: Eu^(3+)), Blue (Sr,Ca,Ba)_(10)(PO_4)_6Cl_2: Eu^(2+) and Green (LaPO_4:Tb^(3+),Ce^(3+)) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3： Eu^3＋）, blue （Sr, Ca, Ba）10（PO4）6Cl2： Eu^2＋ and green （LaPO4： Tb^3＋, Ce^3＋） fine tricolor phosphor powders was established. First, the green phosphor was extracted and separated from three phosphor mixtures in heptane/DMF（N, N-Dimethylformamide） system using stearylamine or laurylamine （DDA） as the cationic surfactant. Then, after being treated with 99.5% ethanol, the blue and red phosphors could be separated in Heptane/DMF system in presence of 1-octanesulfonic acid sodium salt as the anionic surfactant. Satisfactory separation results have been achieved through two steps extractions with their artificial mixtures. The grades and recovery of separated products reached respectively as follows： red product was 95.3% and 90.9%, blue product was 90.0% and 95.2%, and green product was 92.2% and 91.8%.

Experimental investigation on coal pore-fracture variation and fractal characteristics synergistically affected by solvents for improving clean gas extraction

Chemical solvents instead of pure water being as hydraulic fracturing fluid could effectively increase permeability and improve clean methane extraction efficiency.However,pore-fracture variation features of lean coal synergistically affected by solvents have not been fully understood.Ultrasonic testing,nuclear magnetic resonance analysis,liquid phase mass spectrometry was adopted to comprehensively analyze pore-fracture change characteristics of lean coal treated by combined solvent(NMP and CS_(2)).Meanwhile,quantitative characterization of above changing properties was conducted using geometric fractal theory.Relationship model between permeability,fractal dimension and porosity were established.Results indicate that the end face fractures of coal are well developed after CS2and combined solvent treatments,of which,end face box-counting fractal dimensions range from 1.1227 to 1.4767.Maximum decreases in ultrasonic longitudinal wave velocity of coal affected by NMP,CS_(2)and combined solvent are 2.700%,20.521%,22.454%,respectively.Solvent treatments could lead to increasing amount of both mesopores and macropores.Decrease ratio of fractal dimension Dsis 0.259%–2.159%,while permeability increases ratio of NMR ranges from 0.1904 to 6.4486.Meanwhile,combined solvent could dissolve coal polar and non-polar small molecules and expand flow space.Results could provide reference for solvent selection and parameter optimization of permeability-enhancement technology.

Solvent extraction and separation of copper from base metals using bifunctional ionic liquid from sulfate medium

A novel solvent extraction process for extraction and separation of copper from other base metal ions using a bifunctional ionic liquid (IL) (trioctylmethylammonium/2,4,4-trimethylpentyl phosphinate, [A336/Cy272]) in kerosene was reported. This IL was found to extract copper more efficiently than the individual extractants Aliquat 336 or Cyanex 272. Formation of an octahedral copper-IL complex was characterized by UV-Visible spectra and metal ligand interaction was confirmed by FTIR spectra. The loading capacity of 0.1 mol/L [A336/Cy272] was found to be 1.71 g/L. Stripping studies reported that 0.298 g/L copper ions were efficiently stripped using 0.1 mol/L sulfuric acid from 0.05 mol/L loaded IL. The selectivity of copper against nickel, cadmium and iron was investigated from their equimolar binary mixtures using 0.05 mol/L [A336/Cy272] in kerosene. The highest separation factorβCu/Cd=8.41 was obtained at pH 3.56. Copper can be effectively separated from nickel over the pH range studied. The IL extracts preferentially iron over copper and the highest separation factorβFe/Cuwas 3246 at pH 2.4. The extraction rate of metal ions from a synthetic solution containing copper with other metal impurities was in the order of Fe>Zn>Cu>Cd>Co>Ni.

Kinetics and mechanisms of solvent extraction and separation of La(Ⅲ) and Ni(Ⅱ) with DEHPA in petrofin

The kinetics of extractive separation of La(Ⅲ) and Ni(Ⅱ) from nitrate medium in the presence of lactic acid (HLac) using di-2-ethylhexyl phosphoric acid (DEHPA) diluted in petrofin was investigated using a cell with constant interfacial area and continuous stirring. The effects of stirring speed, interfacial area, pH, HLac concentration, extractant concentration, concentrations of metal ions and temperature on the extraction rate were examined. Results suggested that the extraction regime is diffusion-controlled. The reaction which occurred at the interface was found to be the rate-determining step. The extraction rates of both metal ions are found to be independent of pH. The extraction rates of La(Ⅲ) and Ni(Ⅱ) are first-order dependent with respect to lactic acid and metal ions (La(Ⅲ) and Ni(Ⅱ)) concentrations. The extraction rate of La(Ⅲ) is first-order dependent on DEHPA concentration and for Ni(Ⅱ), it varies to the power of 1.5. The separation of La(Ⅲ) and Ni(Ⅱ) from nitrate solution is possible at low interfacial area and low stirring speed.

Separation of Red (Y_2O_3:Eu^(3+)), Blue (BaMgAl_(10)O_(17):Eu^(2+)) and Green (CeMgAl_(10)O_(17):Tb^3) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3：Eu^3＋）, blue（BaMgAl10O17：Eu^2＋） and green （CeMgAl10O17：Tb^3） rare earth fluorescent powders was proposed. At first, the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone （TTA） dissolved in heptane at alkaline pH condition, then, chloroform was used for extracting the green powder into organic phase. The red phosphor remains in aqueous phase with potassium sodium tartrate depressant （PST）. Therefore, three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction, and grades and recovery of separated products reach respectively as follows： red is 96.9% and 95.2%, blue is 82.7% and 98.8%, green is 94.6% and 82.6%.

Phase separation in solvent extraction of cobalt from acidic sulfate solution using synergistic mixture containing dinonylnaphthalene sulfonic acid and 2-ethylhexyl 4-pyridinecarboxylate ester

Phase separation rate is a critical character in determining the usefulness of a solvent extraction system in hydrometallurgy. A survey of the synergistic mixture containing dinonylnaphthalene sulfonic acid (HDNNS) and 2-ethylhexly 4-pyridinecarboxylate ester (4PC) for the extraction of cobalt from acidic single metal sulfate solution was carried out to suggest how the physicochemical properties and the morphology of the reverse micelles in the loaded organic phase affect the phase separation. The results show that effective parameters affecting the phase separation are the viscosity and the excess water uptake of the loaded organic phase. It is obvious that the specific settling rate (SSR) decreases with the apparent increase of these two parameters. The measurement of small angle X-ray scattering (SAXS) proves that the morphology of the reversed micelles in the loaded organic phase changes evidently with the change of the specific settling rate (SSR).

Separation of tungsten and molybdenum with solvent extraction using functionalized ionic liquid tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate

Functionalized ionic liquids(FILs)as extractants were employed for the separation of tungsten and molybdenum from a sulfate solution for the first time.The effects of initial pH,extractant concentration,metal concentrations in the feed were comprehensively investigated.The results showed that tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate([A336][Cyanex272])could selectively extract W over Mo at an initial pH value of 5.5;the best separation factorβ_(W/Mo) of 25.61 was obtained for a solution with low metal concentrations(WO3:2.49 g/L,Mo:1.04 g/L).The[A336][Cyanex272]system performed effectively for solutions of different W/Mo molar ratios and different metal ion concentrations in the feed.The chemical reaction between[A336][Cyanex272]and W followed the ion association mechanism,which was further proved by the Fourier-transform infrared(FTIR)spectra of loaded[A336][Cyanex272]and the free extractant.The stripping experiments indicated that 95.48%W and 100.00%Mo were stripped using a 0.20 mol/L sodium hydroxide solution.Finally,the selective extractions of W and Mo from two synthetic solutions of different high metal concentrations were obtained;the separation factorβW/Mo reached 23.24 and 17.59 for the first and second solutions,respectively.The results suggest the feasibility of[A336][Cyanex272]as an extractant for the separation of tungsten and molybdenum.

Three-liquid-phase extraction and separation of V(V) and Cr(VI) from acidic leach solutions of high-chromium vanadium–titanium magnetite

A new method by liquid-liquid-liquid three phase system, consisting of acidified primary amine N1923 （abbreviated as A-N1923）, poly（ethylene glycol） （PEG） and （NH4）2S04 aqueous solution, was suggested for the separation and simultaneous extraction of Ⅴ（Ⅴ） and Cr（Ⅵ） from the acidic leach solutions of high- chromium vanadium-titanium magnetite. Experimental results indicated that Ⅴ（Ⅴ） and Cr（Ⅵ） could be selectively enriched into the A-N1923 organic top phase and PEG-rich middle phase, respectively, while AI（Ⅲ） and other co-existing impurity ions, such as Si（Ⅳ）, Fe（Ⅲ）, Ti（Ⅳ）, Mg（Ⅱ） and Ca（Ⅱ） in acidic leach solutions, could be enriched in the （NH4）2SO4 bottom aqueous phase. During the process for extraction and separation of Ⅴ（Ⅴ） and Cr（Ⅵ）, almost all of impurity ions could be removed. The separation factors between Ⅴ （Ⅴ） and Cr（Ⅵ） could reach 630 and 908, respectively in the organic top phase and PEG middle phase, and yields of recovered Ⅴ（Ⅴ） and Cr（Ⅵ） in the top phase and middle phase respectively were all above 90%. Various effects including aqueous pH, A-N1923 concentration, PEG added amount and （NH4）2SO4 concentration on three-phase partitioning of Ⅴ（Ⅴ） and Cr（Ⅵ） were discussed. It was found that the partition of Cr（Ⅵ） into the PEG-rich middle phase was driven by hydrophobic interaction, while extraction of Ⅴ（Ⅴ） by A-N1923 resulted of anion exchange between NO; and H2V10O4-28. Stripping of Ⅴ（Ⅴ） and Cr（Ⅵ） from the top organic phase and the middle PEG-rich phase were achieved by mixing respectively with NANO3 aqueous solutions and NaOH-（NH4）2SO4 solutions. The present work highlights a new approach for the extraction and purification of V and Cr from the complex multi-metal co-existing acidic leach solutions of high-chromium vanadium-titanium magnetite.

Environmental,economic and exergy analysis of separation of ternary azeotrope by variable pressure extractive distillation based on multi-objective optimization

In this work,the ternary azeotrope of tert-butyl alcohol/ethyl acetate/water is separated by extractive distillation(ED)to recover the available constituents and protect the environment.Based on the conductor like shielding model and relative volatility method,ethylene glycol was selected as the extractant in the separation process.In addition,in view of the characteristic that the relative volatility between components changes with pressure,the multi-objective optimization method based on nondominated sorting genetic algorithm II optimizes the pressure and the amount of solvent cooperatively to avoid falling into the optimal local solution.Based on the optimal process parameters,the proposed heat-integrated process can reduce the gas emissions by 29.30%.The heat-integrated ED,further coupled with the pervaporation process,can reduce gas emission by 42.36%and has the highest exergy efficiency of 47.56%.In addition,based on the heat-integrated process,the proposed two heat pump assisted heat-integrated ED processes show good economic and environmental performance.The double heat pump assisted heat-integrated ED can reduce the total annual cost by 28.78%and the gas emissions by 55.83%compared with the basis process,which has a good application prospect.This work provides a feasible approach for the separation of ternary azeotropes.

Recent Technologies for the Extraction and Separation of Polyphenols in Different Plants:A Review

Polyphenol is an important secondary metabolite with unique physiological functions and biological activity.The polyphenols in different plants and biomass have different chemical structures,which needs various extraction methods to obtain them.Recently,plant polyphenols and their application research in food and medicine have become a research hotspot,which is mainly focused on preparation,purification,structural identification,and biological activity assays.Among these researches,extraction and separation are the key sections to investigate the structure and activity of polyphenol.Hence,this review summarized the recent extraction and separation techniques of polyphenol,including solvent extraction,supercritical fluid extraction,ultrasonic extraction,enzymatic extraction,resin adsorption extraction,and electric field method,etc.In addition,this review also reveals the current problems and proposes future extraction research of polyphenol.It is hoped that this review will provide a guide for the researchers who are actively committed to promoting progress in the field of polyphenolics.

Process development for the direct solvent extraction of nickel and cobalt from nitrate solution:aluminum,cobalt,and nickel separation using Cyanex 272

A direct solvent extraction（DSX） process for purifying nickel and cobalt from the nitric acid leach solution of nickel laterite ores was conceived and experimentally probed. The proposed process consists of two solvent extraction（SX） steps but with only one extractant - bis（2,4,4-trimethylpentyl）phosphinic acid（Cyanex？ 272） - used in both steps. The first extraction step involved the removal of aluminum and zinc, whereas the second extraction step involved the separation of cobalt along with manganese from nickel. The experimental results showed essentially quantitative removal of aluminum（〉97%） and zinc（〉99%） in a single extraction stage using 20vol% Cyanex 272 at pH 2.1. Some cobalt（32%） and manganese（55%） were co-extracted but were easily scrubbed out completely from the loaded organic phase using dilute sulfuric acid at pH ≤ 1.38. Cobalt and manganese in the first extraction raffinate were extracted completely in four extraction stages at staggered pH values of 4.0, 4.4, 4.5, and 4.0 in the first, second, third, and fourth stages, respectively, using also 20vol% Cyanex 272. A small amount of nickel（up to 6.6%） was co-extracted but was easily scrubbed out completely with dilute sulfuric acid at pH 2.0. A flow diagram showing the input and output conditions and the metals separated under the deduced optimum conditions is presented.

Kinetics and mechanism of Re(Ⅶ) extraction and separation from Mo(Ⅵ) with trialkyl amine

The extraction kinetics of rhenium(Ⅶ) or molybdenum(Ⅵ) with trialkyl amine (N235, R3N, R=C8–C10) dissolved in heptane were investigated by constant interfacial cell with laminar flow, which aimed to identify the extraction regime, reaction zone and rate equations. The influence of stirring speed, temperature, specific interfacial area, extraction concentration and chlorine concentration on the extraction of both metals was studied. It is concluded that the extractions of Re(Ⅶ) and Mo(Ⅵ) both take place at the liquid-liquid interface, while the extraction regimes are chemically-controlled for rhenium and mixed controlled for molybdenum, respectively. The extraction rate equations and the rate-determining step were obtained under the experimental conditions, and the extraction rate constant of Re(Ⅶ) or Mo(Ⅵ) with N235 was calculated. These obtained kinetics parameters are different between Re(Ⅶ) and Mo(Ⅵ), which provides better possibilities for Re(Ⅶ) and Mo(Ⅵ) separations at proper conditions.