Electrorefining of aluminum in urea-imidazole chloride-aluminum chloride ionic liquids

The electrochemical behavior of Al(Ⅲ)in urea-1-butyl-3-methylimidazolium chloride-aluminum chloride(urea-BMIC-AlCl_(3))ionic liquids,and the effect of potential and temperature on the characterization of cathode products,current efficiency and energy consumption of aluminum electrorefining have been investigated.Cyclic voltammetry showed that the electrochemical reduction of Al(Ⅲ)was a one-step three-electron-transfer irreversible reaction,and the electrochemical reaction was controlled by diffusion.The diffusion coefficient of Al(Ⅲ)in urea-BMIC-AlCl_(3)ionic liquids at 313 K was 1.94×10^(−7)cm^(2)/s.The 7075 aluminum alloy was used as an anode for electrorefining,and the cathode products were analyzed by XRD,SEM and EDS.The results from XRD analysis indicated that the main phase of the cathode products was aluminum.The results from SEM and EDS characterization revealed that the cathode product obtained by electrorefining−1.2 V(vs.Al)was dense and uniform,and the mass fraction of aluminum decreased from 99.61%to 99.10%as the experimental temperature increased from 313 K to 333 K.In this work,the optimum experimental conditions were−1.2 V(vs.Al)and 313 K.At this time,the cathode current efficiency was 97.80%,while the energy consumption was 3.72 kW·h/kg.

Direct observation of ordered-disordered structural transition of MoS_(2)-confined ionic liquids

Ionic liquids(ILs)are an emerging class of media of fundamental importance for chemical engineering,especially due to their interaction with solid surfaces.Here,we explore the growth phenomenon of surface-confined ILs and reveal a peculiar structural transition behavior from order to disorder above a threshold thickness.This behavior can be explained by the variation of interfacial forces with increasing distance from the solid surface.Direct structural observation of different ILs highlights the influence of the ionic structure on the growth process.Notably,the length of the alkyl chain in the cation is found to be a determining factor for the ordering trend.Also,the thermal stability of surface-confined ILs is investigated in depth by controlling annealing treatments.It is found that the ordered monolayer ILs exhibit high robustness against high temperatures.Our findings provide new perspectives on the properties of surface-confined ILs and open up potential avenues for manipulating the structures of nanometer-thick IL films for various applications.

Solvent effects on Diels-Alder reaction in ionic liquids:A reaction density functional study

Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and selectivity.However,the underlying microscopic mechanism remains ambiguous.In this work,the multiscale reaction density functional theory is applied to explore the effect of 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF_(6)])solvent on the reaction of cyclopentadiene(CP)with acrolein,methyl acrylate,or acrylonitrile.By analyzing the free energy landscape during the reaction,it is found that the polarization effect has a relatively small influence,while the solvation effect makes both the activation free energy and reaction free energy decrease.In addition,the rearrangement of local solvent structure shows that the cation spatial distribution responds more evidently to the reaction than the anion,and this indicates that the cation plays a dominant role in the solvation effect and so as to affect the reaction rates and selectivity of the DA reactions.

Highly defective HKUST-1 with excellent stability and SO_(2) uptake: The hydrophobic armor effect of functionalized ionic liquids

Water stability is one of the most important factors restricting the practical application of metal organic frameworks (MOFs). In this work, wefabricate a highly defective HKUST-1 framework with a mixed valence of CuI/CuIIby mechanical ball milling method. This defective HKUST-1is embellished by functionalized ionic liquids as hydrophobic armor, making the hybrid HIL1@HKUST-1 exhibits outstanding water stability,remarkable SO_(2) adsorption (up to 5.71 mmol g^(-1)), and record-breaking selectivity (1070 for SO_(2)/CO_(2) and 31,515 for SO_(2)/N_(2)) at 25 ℃ and0.1 bar, even in wet conditions.

Universal basis underlying temperature, pressure and size induced dynamical evolution in metallic glass-forming liquids

The dramatic temperature-dependence of liquids dynamics has attracted considerable scientific interests and efforts in the past decades, but the physics of which remains elusive. In addition to temperature, some other parameters, such as pressure, loading and size, can also tune the liquid dynamics and induce glass transition, which makes the situation more complicated. Here, we performed molecular dynamics simulations for Ni_(50)Zr_(50) bulk liquid and nanodroplet to study the dynamics evolution in the complex multivariate phase space, especially along the isotherm with the change of pressure or droplet size. It is found that the short-time Debye–Waller factor universally determines the long-time relaxation dynamics no matter how the temperature, pressure or size changes. The basic correlation even holds at the local atomic scale. This finding provides general understanding of the microscopic mechanism of dynamic arrest and dynamic heterogeneity.

Highly selective extraction of aromatics from aliphatics by using metal chloride-based ionic liquids

The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and their performances in the separation of 1,2,3,4-tetrahydronaphthalene(tetralin)/dodecane and tetralin/decalin systems were studied.Among these ionic liquids,1-ethyl-3-methylimidazolium tetrachloroferrate([EMIM][FeCl_(4)])with the highest selectivity was used as the extractant.Density functional theory calculations showed that[EMIM][FeCl_(4)]interacted more strongly with tetralin than with dodecane and decalin.Energy decomposition analysis of[EMIM][FeCl_(4)]-tetralin indicated that electrostatics and dispersion played essential roles,and induction cannot be neglected.The van der Waals forces was a main effect in[EMIM][FeCl_(4)]-tetralin by independent gradient model analysis.The tetralin distribution coefficient and selectivity were 0.8 and 110,respectively,with 10%(mol)tetralin in the initial tetralin/dodecane system,and 0.67 and 19.5,respectively,with 10%(mol)tetralin in the initial tetralin/decalin system.The selectivity increased with decreasing alkyl chain length of the extractant.The influence of the extraction temperature,extractant dosage,and initial concentrations of the system components on the separation performance were studied.Recycling experiments showed that the regenerated[EMIM][FeCl_(4)]could be used repeatedly.

Impact of ethanol on the flotation efficiency of imidazolium ionic liquids as collectors:Insights from dynamic surface tension and solvation analysis

To conduct extensive research on the application of ionic liquids as collectors in mineral flotation,ethanol(EtOH)was used as a solvent to dissolve hydrophobic ionic liquids(ILs)to simplify the reagent regime.Interesting phenomena were observed in which EtOH exerted different effects on the flotation efficiency of two ILs with similar structures.When EtOH was used to dissolve 1-dodecyl-3-methylimidazolium chloride(C12[mim]Cl)and as a collector for pure quartz flotation tests at a concentration of 1×10^(−5)mol·L^(−1),quartz recovery increased from 23.77%to 77.91%compared with ILs dissolved in water.However,quartz recovery of 1-dodecyl-3-methylim-idazolium hexafluorophosphate(C12[mim]PF6)decreased from 60.45%to 24.52%under the same conditions.The conditional experi-ments under 1×10^(−5)mol·L^(−1)ILs for EtOH concentration and under 2vol%EtOH for ILs concentration confirmed this difference.After being affected by EtOH,the mixed ore flotation tests of quartz and hematite showed a decrease in the hematite concentrate grade and re-covery for the C12[mim]Cl collector,whereas the hematite concentrate grade and recovery for the C12[mim]PF6 collector increased.On the basis of these differences and observations of flotation foam,two-phase bubble observation tests were carried out.The EtOH promoted the foam height of two ILs during aeration.It accelerated static froth defoaming after aeration stopped,and the foam of C12[mim]PF6 de-foaming especially quickly.In the discussion of flotation tests and foam observation,an attempt was made to explain the reasons and mechanisms behind the diverse phenomena using the dynamic surface tension effect and solvation effect results from EtOH.The solva-tion effect was verified through Fourier transform infrared(FT-IR),X-ray photoelectron spectroscopy(XPS),and Zeta potential tests.Al-though EtOH affects the adsorption of ILs on the ore surface during flotation negatively,it holds an positive value of inhibiting foam mer-ging during flotation aeration and accelerating the defoaming of static foam.And induce more robust secondary enrichment in the mixed ore flotation of the C12[mim]PF6 collector,facilitating effective mixed ore separation even under inhibitor-free conditions.

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs;as novel solvents for improving the solubility of drugs in carriers;as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs;and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

Separation of lithium and nickel using ionic liquids and tributyl phosphate

With the vigorous development of the electronics industry,the consumption of lithium continues to increase,and more lithium needs to be mined to meet the development of the industry.The content of lithium in the solution is much higher than that of minerals,but the interference of impurity ions increases the difficulty of extracting lithium ions.Therefore,we prepared an imidazole-based ionic liquid(1-butyl-3-methylImidazolium bis(trifluoromethyl sulfonyl)imide)(IL)for efficient lithium extraction from aqueous solutions by solvent extraction.Using an extraction consisting of 10%IL,85% tributyl phosphate(TBP),and 5% dichloroethane and an organic to aqueous phase ratio(O/A)of 2/1,over 64.23% of Li were extracted,and the extraction rate after five-stage extraction could reach more than 96%.The addition of ammonium ions to the solution inhibited the extraction of Ni,and the separation coefficient between lithium and nickel approached infinity,showing a very perfect separation effect.Fouriertransform infrared spectroscopy and slope methods were used to analyze the changes that occurred during extraction,revealing possible extraction mechanisms.In addition,the LiCl solution generated during the preparation of ionic liquids was mixed with the stripping solution,and the battery-grade lithium carbonate was prepared by Na_(2)CO_(3) precipitation,with a purity of 99.74%.This study provides an efficient and sustainable strategy for recovering lithium from the solution.

A simple hydroxypyridine ionic liquids for conversion of CO_(2)into quinazoline-2,4(1H,3H)-diones under atmospheric conditions

The transformation of CO_(2)into high value-added product is a promising pathway for utilizing CO_(2).However,the process tends to require harsh reaction conditions owing to CO_(2)chemical inertness.Designing a high efficiency catalytic system with environmentally benign characteristic are important determinants.In this work,protic ionic liquids[TMG][2-OPy]were prepared via one-step neutralization between 1,1,3,3-tetramethylguanidine and 2-hydroxypyridine,applying to the domain of synthesizing quinzoline-2,4(1 H,3H)-diones from CO_(2)and 2-aminobenzontiles without any solvent or metal,achieving the yield of 97%at 90℃for 8 h under atmospheric.A series of substrates with good to acceptable yield were detected,revealing the generality and universality of the catalyst.Furthermore,the system could be facilely reused for at least six runs,retaining the yield of 94%.A preliminary kinetic equation is calculated with the activation energy of 68 kJ·mol^(-1),and a plausible reaction mechanism was put forward.This study highlights that the[TMG][2-OPy]enables to activate CO_(2)carboxylation efficiently.

The opportunities and challenges of ionic liquids in perovskite solar cells

Metal halide perovskite solar cells(PSCs)have shown great potential to become the next generation of photovoltaic devices due to their simple fabrication techniques,low cost,and soaring power conversion efficiency(PCE).However,mismatched with the quickly updated PCEs,the improvement of device stability is challenging and still remains a critical hurdle in the path to commercialization.Recently,ionic liquids(ILs)have been found to play multiple roles in obtaining efficient and stable PSCs.These ILs usually consist of large organic cations and organic or inorganic anions,which have weak electrostatic attraction and are generally liquid at around 100℃.ILs are almost non-volatile,non-flammable,with high ionic conductivity and excellent thermal and electrochemical stability.The roles of ILs in PSCs vary with their composition,that is,the types of anions and cations.In this review,we summarize the roles of anions and cations in terms of precursor solutions,additives,perovskite/charge transport layer interface engineering,and charge transport layers.This article aims to set up a structure–property-stability-performance correlations conferred by the IL in PSC and provide assistance for the anion and cation selection for improving the quality of perovskite film,optimizing interface contact,reducing defect states,and improving charge extraction and transport characteristics.Finally,the application of IL in PSCs is discussed and prospected.

Complete degradation of high-loaded phenol using tungstate-based ionic liquids with long chain substituent at mild conditions

Phenol in waste water threatens human health and is difficultly to be decomposed by nature.Efficient degradation of high-loaded phenol in water under mild condition is still a great challenge.Herein,ionic liquids with tungstate anion were designed and prepared.It was found that dodecyltrimethylammonium tungstate could catalyzed degradation of phenol into gases and water thoroughly at 323 k in 8 h.Tungstate anion revealed good catalytic oxidative activity and long carbon chain group connecting with cation of ionic liquids enriched phenol around catalysts,which induced the complete degradation of phenol at mild conditions.Increasing the amounts of hydrogen peroxide benefited to the total degradation of phenol.In addition,the ionic liquid could be reused for its excellent thermal stability.Our work provided a different strategy to treat waste water containing phenol efficiently.

Ionic liquids-SBA-15 hybrid catalysts for highly efficient and solvent-free synthesis of diphenyl carbonate

Diphenyl carbonate(DPC)is one of the versatile carbonates,and is often used for the production of polycarbonates.In recent years,the catalytic synthesis of DPC has become an important topic but the development of a highly active metal-free catalyst is a great challenge.Herein,a series of ionic liquids-SBA-15 hybrid catalysts with different functional groups have been developed for the synthesis of DPC under solventfree condition,which are effective and clean instead of the metal-containing catalysts.It is found that in the presence of[SBA-15-IL-OH]Br catalyst,methyl phenyl carbonate(MPC)conversion of 80.5%along with 99.6%DPC selectivity is achieved,the TOF value is thrice higher than the best value reported by using transition metal-based catalysts.Moreover,the catalyst displays remarkable stability and recyclability.This work provides a new idea to design and prepare eco-friendly catalysts in a broad range of applications for the green synthesis of carbonates.

Modeling of liquid film thickness around Taylor bubbles rising in vertical stagnant and co-current slug flowing liquids

The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles.The prediction models for liquid film thickness mainly focus on stagnant flow,and some of them remain inaccurate performance.However,in the industrial process,the slug flow essentially is co-current flow.Therefore,in this paper,the liquid film thickness is studied by theoretical analysis and experimental methods under two conditions of stagnant and co-current flow.Firstly,under the condition of stagnant flow,the present work is based on Batchelor's theory,and modifies Batchelor's liquid film thickness model,which effectively improves its prediction accuracy.Under the condition of co-current flow,the prediction model of average liquid film thickness in slug flow is established by force and motion analysis.Taylor bubble length is introduced into the model as an important parameter.Dynamic experiments were carried out in the pipe with an inner diameter of 20 mm.The liquid film thickness,Taylor bubble velocity and length were measured by distributed ultrasonic sensor and intrusive cross-correlation conductivity sensor.Comparing the predicted value of the model with the measured results,the relative error is controlled within 10%.

Preparation of Ionic Liquids Immobilized on FMIL-101 Catalysts for Conversion of CO_(2)to Propylene Carbonate

Metal-organic frameworks(MOFs)have attracted considerable research attention as a new type of porous material for catalytic applications.Herein,2,5-dihydroxyterephthalic acid was proposed to replace conventional terephthalic acid and reacted with chromic nitrate nonahydrate to synthesize a functional metal–organic framework(FMIL-101).This was then used to immobilize various compound ionic liquids to prepare three ionic liquids immobilized on FMIL-101 catalysts,namely,FMIL-101-[HeMIM]Cl/(ZnBr_(2))_(2),FMIL-101-[CeMIM]Cl/(ZnBr_(2))_(2),and FMIL-101-[AeMIM]Br/(ZnBr_(2))_(2).After characterization by Fourier-transform infrared spectroscopy,X-ray diffraction,ultraviolet spectroscopy,thermogravimetry,specific surface area analysis,and scanning electron microscopy,the catalysts were used to mediate cycloaddition reactions between carbon dioxide(CO_(2))and propylene oxide.The effects of reaction temperature,reaction pressure,reaction time,and catalyst dosage on the catalytic performance were investigated.The results revealed that the FMIL-101-supported CIL catalysts afforded the target product propylene carbonate with good catalytic performance and thermal stability.The optimal catalyst,FMIL-101-[CeMIM]Cl/(ZnBr_(2))_(2),displayed a propylene oxide conversion of 98.64%and a propylene carbonate selectivity of 96.63%at a reaction temperature of 110℃,a reaction pressure of 2.0 MPa,a catalyst dosage of 2.0%relative to propylene oxide,and a reaction time of 2.5 h.In addition,the conversion and selectivity of the catalyst decreased slightly after four cycles.Additionally,the catalyst decreased slightly in catalytic performance after being recycled four times.

Electrodeposition of Al on AZ31 magnesium alloy in TMPAC-AlCl_3 ionic liquids

Aluminum was electrodeposited with constant current on AZ31 magnesium alloy pretreated under optimized conditions from trimethyl-phenyl-ammonium chloride and anhydrous aluminum chloride （TMPAC-AlCl3） quaternary ammonium room temperature ionic liquids with benzene as a co-solvent. The corrosion resistance of the as-deposited Al layers was evaluated in 3.5% NaCl solution by the electrochemical technologies. The Al depositions were characterized by scanning electron microscopy equipped with energy dispersion X-ray. The results show that the microstructures of the Al depositions have spherical equiaxed grains obtained at a high current density, and bulk grains at a low current density. The Al deposition obtained at 12.3 mA/cm2 has a smooth and compact surface. The electrochemical measurements indicate that the thicker Al deposition can more effectively protect the Mg substrate. The Al deposition with bulk grains hardly protects the AZ31 Mg substrate from corrosion owing to its porosity.

Surface pretreatment of Mg alloys prior to Al electroplating in TMPAC-AlCl_3 ionic liquids

It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarization curves, to produce a compact interfacial layer as zinc-immersion deposition. After the substrate was pretreated under optimized conditions, aluminum was electrodeposited on AZ31 from TMPAC-AlCl3 room temperature ionic liquids. The depositions were characterized by scanning electron microscope equipped with energy dispersion X-ray. The results show that the traditional pretreatment of Mg alloys was successfully used for the Al-electroplating process from TMPAC-AlCl3 ionic liquids. The entire procedure includes alkaline cleaning, chemical pickling, surface activation （400 mL/L HF acid, 10 min）, zinc-immersion （20 min） and anhydrous treatment. A relatively compact zinc-immersion film was prepared on the substrate surface. A silvery-colored satin aluminum deposition was obtained on AZ31 from TMPAC-AlCl3 using direct current plating.

The Future of Gas to Liquids as a Gas Monetisation Option

The paper introduces gas to liquids (GTL) as a monetising option from a technology, marketing and project perspective. GTL is complementary to LNG and pipelines. At the same time, using natural gas as a source for fuels in the form of GTL helps countries around the world to diversify their energy supplies. Furthermore, gas-based products are inherently cleaner than oil products. Shell's proprietary GTL technology or SMDS (Shell Middle Distillates Synthesis), is discussed in some detail. The paper also covers the challenges for successful implementation of GTL projects and why Shell is well positioned to take a lead in the industry on the basis of its long standing and broad experience in GTL research, plant operations, marketing and excellent track record in mega projects in the last thirty years. Shell's commitment to GTL is best demonstrated by the recent signing of a Heads of Agreement with Qatar Petroleum for the construction of the world's largest GTL plant. A key success factor is Shell's experience with marketing quantities of high quality GTL products from its 12,500 barrels per day plant at Bintulu, Malaysia since 1993. Further marketing opportunities will arise when new GTL capacity comes on-stream in the middle east when more quantities will become available to bulk users. Amongst the most interesting market will be automotive transportation, where clean GTL fuels can be positioned as an 'alternative fuel beyond oil' providing energy security to host countries. Shell is actively engaging with a number of regulators, automotive companies and governments worldwide including China, to demonstrate the performance of GTL and its cost effectiveness in reducing local emissions. An added benefit is that GTL can use existing infrastructure and requires no investment. Finally, the paper briefly discusses the coal to liquids (CTL) process as an alternative route to produce high quality GTL products and the key issues relating to the process.

Insight into Capture of Greenhouse Gas （CO2） based on Guanidinium Ionic Liquids

Quantum mechanics and molecular dynamics are used to simulate guanidinium ionic liquids. Results show that the stronger interaction exists between guanidine cation and chlorine anion with interaction energy about 109.216 kcal/mol. There are two types of spatial distribution for the title system： middle and top. Middle mode is a more stable conformation according to energy and geometric distribution. It is also verified by radial distribution function. The continuous increase of carbon dioxide （CO2） does not affect the structure of ionic liquids, but CO2 molecules are always captured by the cavity of ionic liquids.

Toxicity of Selected Imidazolium-based Ionic Liquids on Caenorhabditis elegans： a Quantitative Structure-Activity Relationship Study

Due to the large number of ionic liquids （ILs） and their potential environmental risk, assessing the toxicity of ILs by ecotoxicological experiment only is insufficient. Quantitative structure- activity relationship （QSAR） has been proven to be a quick and effective method to estimate the viscosity, melting points, and even toxicity of ILs. In this work, the LC50 values of 30 imidazolium-based ILs were determined with Caenorhabditis elegans as a model animal. Four suitable molecular descriptors were selected on the basis of genetic function approximation algorithm to construct a QSAR model with an R^2 value of 0.938. The predicted lgLC50 in this work are in agreement with the experimental values, indicating that the model has good stability and predictive ability. Our study provides a valuable model to predict the potential toxicity of ILs with different sub-structures to the environment and human health.