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Ionic liquids (ILs) are key materials for the development of a wide range of emerging technologies. Protic ionic liquids, an important class of ILs, have long been envisioned as promising anhydrous electrolytes for fuel cells. It is well known that in comparison to all other cations, protons exhibit abnormally high conductivity in water. Such superprotonic dynamics was expected in protic ionic conductors as well. However, many years of extensive studies led to the disappointing conclusion that this is not the case and most protic ionic liquids display subionic behavior. Therefore, the relatively low conductivity seems to be the main obstacle for the application of protic ionic liquids in fuel cells. Using dielectric spectroscopy, herein we report the observation of highly decoupled conductivity in a newly synthesized protic ionic conductor. We show that its proton transport is strongly decoupled from the structural relaxation, in terms of both temperature dependence and characteristic rates. This finding offers a fresh look on the charge transport mechanism in PILs and also provides new ideas for design of anhydrous materials with exceptionally high proton conductivity.

Biobutanol is a green solvent commonly used as gasoline additive. In this study, it is proposed the separation of azeotropic mixtures of butanol and n‐butyl ether (DBE) using ionic liquids (ILs). Suitable anions [AC]− and [H2PO4]− were screened by COSMO‐RS, and the effect of carbon chain length on the separation effect was investigated using quantum chemical calculations. It was found that the anion was primarily responsible for the separation effect, which grew as the carbon chain grew. Molecular dynamics simulations were used to verify the separation performance of the selected ILs. The separation effect of ILs was further verified using vapor–liquid phase equilibrium (VLE) experiments. The extractive distillation process with [PrMIM][AC] as the extractant was investigated to demonstrate the feasibility of ILs for the separation of butanol and DBE. This study analyzes the whole process from microscopic mechanism of action, which provides new ideas for the separation of alcohol‐ether systems. [ABSTRACT FROM AUTHOR]

• Recovering 2-Methoxyethanol from wastewater has environmental and economic benefits. • Mixed solvents based on ionic liquids are used for extractive distillation. • The interaction mechanism is analyzed from the microscopic perspective. • Research process strengthening technology to save energy and reduce consumption. • The processes are considered from economic, environmental, and exergy. 2-Methoxyethanol is an important solvent with wide application prospects. Recovering 2-Methoxyethanol from wastewater has significant environmental and economic benefits. In this work, quantum chemistry methods are used to calculate the surface electrostatic potential, mutual penetration analysis, and reduced density gradient-independent gradient model of solvents and azeotrope. From the perspective of the mechanism of action, suitable extractants are selected. With the minimum total annual cost as the goal, the splendid process parameters and the excellent ratio of mixed solvents (30 % 1-ethyl-3-methylimidazole acetate + 70 % N, N-dimethyl acetamide) are acquired. Moreover, two reinforcing processes for energy saving and consumption reduction are also researched. All processes are appraised from three aspects: economy, environment and exergy. The results show that the total annual cost and gas emission of mixed solvent extraction distillation are reduced by 26.79 % and 35.45 %, respectively, compared with the process with NMP as an entrainer. Compared with the process with [EMIM][AC] as an entrainer, the total annual cost and gas emissions are reduced by 44.99 % and 25.04 %, respectively. Relative to mixed solvent, the total annual cost and gas emissions of the heat pump combined with mixed solvent extractive distillation technology decreased by 6.77 % and 21.78 % respectively, while that of the heat integration process decreased via 9.93 % and 12.30 % respectively. From the point of view of environmental sustainability, the process effect combined with the heat pump is better, and from the point of view of economic benefits, the heat integration process has better performance. This study reveals the intrinsic relationship between the structure of mixed solvents and explores the intensification of the process, which provides a theoretical basis for the industrial separation of 2-Methoxyethanol/water azeotrope. [ABSTRACT FROM AUTHOR]

To efficiently recover dipropyl ether/isopropanol from wastewater, realizing resource recycling and clean production, a viable solution for extractive distillation with mixed solvent (Glycerin: [EMIM][SCN] = 0.254: 0.746) was proposed. Quantitative and qualitative methods were used to screen solvents. Based on COSMO-RS, the selectivity of species in 352 ILs was calculated. The interaction relationship between the microscopic molecular structure and separation performance was researched, and the process mechanism of solvents separating the ether-containing ternary azeotropes was revealed. The use of genetic algorithms for multi-objective optimization determined the splendid process parameters. The scheme was evaluated in terms of economic benefits, environmental impact, and exergy losses. Compared with the pressure swing extractive distillation of a single solvent, the total annual cost and gas emission of the technology using mixed entrainers decreased sharply. Combined with Heat-integrated can realize the low-cost recovery of dipropyl ether/isopropanol from wastewater, which has a guiding role in the industrial separation of ternary azeotrope. • Separation dipropyl ether/isopropanol from wastewater used mixed entrainer based on ionic liquids. • Quantitative and qualitative methods were used to screen ionic liquids and organic entrainers. • Revealed the separation mechanism of ether containing ternary azeotropes. • The scheme was evaluated in terms of multiple performance. • Researched process intensification to save energy and reduce consumption. [ABSTRACT FROM AUTHOR]

Liquid–liquid extraction technology based on ionic liquids (ILs) is an efficient and environmentally friendly method to recover Au(III). This work aims to separate Au(III) from hydrochloric acid media using a novel IL [DBA-Pyr][NTf2], which is a pyrrolidinium-based IL functionalized with amide groups. Firstly, experiments have been carried out under optimal conditions, including the concentration, acidity and temperature. It turns out that low concentrations of hydrochloric acid help in Au(III) extraction, while the increase of chloride ion concentrations has an adverse effect. Then, through Job's method, extraction complexes with a molar ratio of [DBA-Pyr][NTf2]-to-Au(III) of 1 : 1 were determined. And, the anion exchange extraction mechanism was confirmed by FT-IR, UV-Vis, and 13C NMR spectroscopies and an electrostatic potential energy (ESP). Under the optimal extraction conditions, it has excellent selectivity to Au(III) compared to both base metal ions and platinum group metals (PGMs). Furthermore, Au(III) could also be recovered from the IL phase using an aqueous solution of thiourea in 95.6% with high selectivity. After 4 cycle experiments, an extraction efficiency of more than 90% is still maintained. The results show that [DBA-Pyr][NTf2] has potential application prospects in Au(III) recovery from hydrochloric acid media. [ABSTRACT FROM AUTHOR]

β-Diketones are often used to separate brine with a high sodium-to‑lithium ratio but cannot be widely used because of their high toxicity and water solubility. In this work, a functionalized ionic liquid was synthesized from 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1-hexyl-3-methylimidazolium chloride, which was verified by FT-IR and 1H NMR spectroscopy. An organic phase system was formed with this ionic liquid as the extractant and 2-octanone as the diluent, which had the advantage of achieving good extraction and separation performances without co-extractant. In addition, the brine used in this work is the real Chaka salt lake brine in Tibet, which provides a reference value for industrial application of separation of metal ions. The experimental conditions were optimized and the single-stage extraction efficiency of Li+ reached up to 94 %. Using LiCl solution and HCl as the washing and stripping reagents, the washing efficiency of Na+ and stripping efficiency of Li+ were above 98 % and 99 %, respectively. The raffinate was used to regenerate the organic phase, which reduced the use of alkaline reagents. Over 10 cycles of the extraction process, the extraction efficiency of Li+ maintained at approximately 86 %. The extraction mechanism was identified as ionic association using slope analysis and ultraviolet and infrared measurements. • A novel extraction system was developed for selective extraction of lithium from Tibetan brine. • The single-stage extraction efficiency of Li+ with the extraction system reached up to 94 %. • The impurity ions could be washed out by using LiCl solutions. • The raffinate could be used to regenerate the organic phase. • The extraction system showed good reusability over 10 cycles of the extraction process. [ABSTRACT FROM AUTHOR]

An electrochemical NO2 gas sensor was fabricated by using high temperature co-fired ceramic (HTCC) process with zirconia ceramics, conductive metal paste and room temperature ionic liquid as the main raw materials. The electrochemical performance of the sensor electrode and the output and response characteristics of the sensor were studied. The results showed that the room temperature ionic liquid 1-butyl-3-methylimidazolium bis-trifluoromethylsulfonyl imide salt used in the experiment was suitable as the electrolyte of the electrochemical NO2 gas sensor, and the suitable working voltage was 1.2 V; when the detection range of the sensor was 0~0.010% (volume fraction), and the accuracy was 1.5% FS. The response time (τ90) of the sensor was 25 s, which was superior to the traditional chamber electrochemical gas sensor. [ABSTRACT FROM AUTHOR]

The novel heteropolyacid ionic liquid 1-methylimidazolium silicotungstate ([Mmim] 4 SiW 12 O 40) was synthesized using a one-step method and subsequently characterized. This compound was then employed as a co-extractant for the removal of lithium from salt lake brine having a high Mg/Li molar ratio, in conjunction with tributyl phosphate (TBP) and γ-heptanolide as the extractant and diluent, respectively. The optimal extraction conditions gave a single-stage lithium ion extraction efficiency of approximately 60 %. More environmentally friendly and efficient processes were also developed. In one approach, a portion of the aqueous phase containing only HCl and LiCl after stripping was used for washing along with an aqueous HCl solution as the stripping agent and Mg(OH) 2 for regeneration. In the alternative method, NaCl and LiCl were used as washing agents while Na 2 CO 3 was employed for stripping and regeneration, reducing the time required without the need for strong acids or bases. This system showed good extraction efficiency stability over 10 consecutive cycles. The mechanism of this process was explored using Fourier transform infrared spectroscopy and 31P nuclear magnetic resonance spectroscopy and the binding capacity of TBP for the metals was found to decrease in the order of Li+ > Na+ > Mg2+ > K+. • The proposed heteropolyacid ionic liquid was synthesized by one-step method. • The single-stage extraction efficiency of lithium ion was approximately 60 %. • The proposed extraction system showed high selectivities for Mg2+, Na+ and K+. • Na 2 CO 3 was used as stripping agent for shorting the process flow. • The proposed extraction system showed good reusability and stability. [ABSTRACT FROM AUTHOR]

Polymerized ionic liquids (PolyILs)are promising candidates forenergy storage and electrochemical devices applications. Understandingtheir ionic transport mechanism is the key for designing highly conductivePolyILs. By using broadband dielectric spectroscopy (BDS), rheology,and differential scanning calorimetry (DSC), a systematic study hasbeen carried out to provide a better understanding of the ionic transportmechanism in PolyILs with different pendant groups. The variationof pendant groups results in different dielectric, mechanical, andthermal properties of these PolyILs. The Walden plot analysis showsthat the data points for all these PolyILs fall above the ideal Waldenline, and the deviation from the ideal line increases upon approachingthe glass transition temperature (Tg).The conductivity for these PolyILs at their Tgs are much higher than the usually reported value ∼10–15S/cm for polymer electrolytes, in which the ionictransport is closely coupled to the segmental dynamics. These resultsindicate a decoupling of ionic conductivity from the segmental relaxationin these materials. The degree of decoupling increases with the increaseof the fragility of polymer segmental relaxation. We relate this observationto a decrease in polymer packing efficiency with an increase in fragility. [ABSTRACT FROM AUTHOR]

Disposable recycling of Au(III), Pd(II) and Pt(IV) from Acidic Medium using UCST-Type IL. [Display omitted] • The temperature-controlled phase transition system was used for Au(III), Pd(II) and Pt(IV) recovery. • The ability of ILs to form solvated hydrogen bonding is correlated with their corresponding UCST. • Anion exchange mechanism was verified by UV–vis, IR, NMR and LC-MS analysis and quantum chemical calculations. • A technical route for effective separation of Au(III), Pd(II) and Pt(IV) was proposed by selecting suitable stripping agents. The development of efficient ionic liquids (ILs) for disposable separation and recovery of various precious metals was of great importance, but still faced difficult challenges. A phase change temperature-controlled system composed of IL and HCl solution was developed for the extraction and separation of Au(III), Pd(II) and Pt(IV) from secondary resources. UCST (upper critical solution temperature)-type IL ([1,4,7-TMTA][Tf 2 N]) possessed outstanding selectivity of precious metals and the property of temperature-controlled phase transition. The ability of ILs to form solvated hydrogen bonds was confirmed by quantum-chemical calculation to be correlated with their corresponding UCST. Different experimental parameters were optimized to explore the extraction behavior of IL. It is noteworthy that homogeneous liquid-liquid extraction system (HLLE) constructed by UCST-type IL could significantly enhance the extraction kinetic of Au(III), Pd(II) and Pt(IV) by decreasing phase interface resistance. For Au(III), Pd(II) and Pt(IV), when the system temperatures were higher than 40 °C, 49 °C and 65 °C, the maximum values were 98.5%, 98.3% and 93.2% at the highest efficiency. In addition, the extraction mechanism of anion exchange was revealed by UV–vis, IR, NMR and LC-MS spectrometry. At last, Au(III), Pd(II) and Pt(IV) could be selectively separated from multi-metal solutions where impurity ions coexist by K 2 C 2 O 4 , NH 3 ·H 2 O and CS(NH 2) 2 /HCl, respectively. After 5 cycles, the extraction performance of [1,4,7-TMTA][Tf 2 N] maintained. In summary, this paper overcame the obstacle of slow kinetics of solvent extraction technology, and pointed out a way for polymetallic co-extraction and separation in HLLE system. [ABSTRACT FROM AUTHOR]

For sustainable development and environmental protection, recovery of critical metals, especially for gold, from secondary resources, has recently attracted substantial attention. In this work, two novel temperature-responsive ionic liquids (TRILs), [EA-TMEDA][Tf 2 N] 2 and [EA-TMHDA][Tf 2 N] 2 , were designed and firstly synthesized for Au(III) extraction from hydrochloric acid medium. The optimum extraction conditions for Au(III) were selected by optimizing the amount of extractant, acidity and other factors. In optimal conditions, TRILs showed excellent extraction performance for Au(III), which could reach 97.5% with [EA-TMEDA][Tf 2 N] 2 and 91% with [EA-TMHDA][Tf 2 N] 2 , respectively. They also exhibited great selectivity in multi-metal solution such as Cu(II), Mn(II) and Co(II). The thermomorphic behaviors were investigated around the upper critical solution temperature (UCST) by the characterization methods of variable-temperature 1H NMR and dynamic light scattering (DLS). The extraction mechanism was also determined as anion exchange mechanism through the maximum metal loading experiments, UV–vis, FT-IR and 13C NMR characterization. In addition, Au(III) could be almost completely stripped by C 2 H 2 O 4 from the loaded IL phase and there was no significant reduction in efficiency after 5 cycles. Hence, the new TRILs offered outstanding extraction performance for the greener and sustainable extraction of Au(III), and will have broad application prospects in the extraction field. Cycling recovery of Au(III) by temperature-responsive ionic liquids. [Display omitted] • Novel temperature-responsive ionic liquids were firstly synthesized and used for Au(III) extraction. • The water-ILs systems displayed adjustable thermomorphic behaviors. • The thermomorphic behaviors were investigated by the variable-temperature 1HNMR and dynamic light scattering (DLS). • [EA-TMEDA][Tf 2 N] 2 and [EA-TMHDA][Tf 2 N] 2 showed the excellent Au(III) extraction ability from secondary resources without adding organic solvents. • Au(III) was stripped by H 2 C 2 O 4 solution and maintained 5 cycles of extraction tests. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3 piperazine-based ionic liquids were screened out for Au(III) and Pt(IV) recovery. • Ionic liquids can be used as both extractant and hydrophobic phase. • Quantum chemical calculation provided theoretical support for this anion exchange mechanism. • The thermodynamic and kinetic properties of extraction were focused research. • Each extraction ability maintained after 5 turns of extraction cycle experiments. Selective recovery of gold and platinum from secondary resources is of great significance under the crisis of resource shortage. Hence, the optimal extractant 1-(2-(dimethylamino) ethyl)-4-methyl-piperazin bis(trifluoromethylsulfonyl)imide ([C 6 -Et-TMEDA-PIP][Tf 2 N] 2) was synthesized and screened out from five piperazine-based ionic liquids (ILs) to construct an IL-water system for Au(III) and Pt(IV) extraction. ILs have high hydrophobicity and low viscosity at room temperature, which can be used as both extractant and hydrophobic phase. The effects of IL dosage, metal concentration and acidity on the extraction efficiency were investigated. Under the optimal conditions, the extraction efficiency of 98.5% (Au(III)) and 97.5% (Pt(IV)) can be achieved. The anion exchange mechanism was verified through the combination of Ultraviolet visible spectroscopy (UV–vis), Nuclear magnetic spectra (NMR) and quantum chemical calculations. Besides that, the two-factor optimization of the extractant dosage and HCl concentration was carried out by Response surface methodology (RSM), and the effective separation of Au(III) and Pt(IV) was successfully achieved. Au(III)/ Pt(IV) was extracted into the IL phase as [Et-TMEDA-PIP+][AuCl 4 -] and can easily be stripped by reduction to Au(0)/Pt(Ⅱ) with H 2 C 2 O 4 /CS(NH 2) 2 -HCl, and each extraction ability maintained after 5 turns of extraction cycle experiments. Since the excellent behaviors showed in the multi-metal selective extraction and cycle experiments, the [C 6 -Et-TMEDA-PIP][Tf 2 N] 2 was regarded as the most potential system for Au(III) and Pt(IV) recovery from HCI medium. [ABSTRACT FROM AUTHOR]

Abstract: An efficient, practical and environmentally benign synthesis of 2-substituted benzothiazoles was developed through RuCl3-catalyzed oxidative condensation of 2-aminothiophenol with aldehyde in ionic liquid by using air as the oxidant. With this procedure, a series of 2-substituted benzothiazoles and benzothiazole/pyrimidine nucleoside hybrids with antimicrobial activities were efficiently prepared from easily accessible starting materials. [Copyright &y& Elsevier]

[Display omitted] The separation of the ternary azeotrope system is still a topic worth studying. An effective method based on a mixed ionic liquids (ILs) extractant was proposed and applied to the separation of isopropanol (IPA), n-hexane (NH) and water (H 2 O) systems. Firstly, the organic solvent and ILs with better separation effects for the two components of the ternary azeotropic system were screened out by relative volatility calculation, quantum chemistry and molecular dynamics calculation. Based on the synergistic effect of dimethyl sulfoxide (DMSO) and 1-ethyl-3-methylimidazolium thiocyanate ([EMIMSCN]), a mixed ILs extractant was designed. It was then applied to three extractive distillation (ED) processes. Aiming at the minimum total process cost and gas emission, an optimization strategy was designed to achieve multi-objective optimization of process flow, the optimal composition and dosage of the mixed extractant were determined. The process results showed that the total annual cost (TAC) and gas emissions from mixed extractive distillation (MED) were 795406.85 $/y and 1536.84 kg/y, and the process energy consumption was 1987.99 kW. Compared with the ED process with DMSO as an extractant, the MED process can save 40.05 % TAC and reduce 30.39 % gas emission and energy consumption. The mixed extractant was carefully studied, and the addition of ILs was analyzed to increase the relative volatility between IPA and H 2 O separated by the extractant. The sensitivity analysis of the key variables of the MED process was carried out. The results show that the feed position of the extractant has the greatest influence on the objective function. Finally, the MED and the mixed extractive distillation under reduced pressure (RPMED) process were intensified, and the heat pump coupled thermal integrated Heat-integrated mixed extractive distillation (HPH-MED) process was determined to be the best process based on environmental pollution and energy consumption considerations. The TAC of the process is 767298.474 $/y, the gas emission is 753.84 kg/y, and the energy consumption of the process is 975.13 kW. Compared with the MED process, TAC is reduced by 3.53 %, and total gas emissions and energy consumption are reduced by 50.95 %. [ABSTRACT FROM AUTHOR]

Inorder to understand the nature of the exceedingly low ionic conductivityof aprotic ammonium ionic liquids (ILs), we have measured the chargetransport and structural dynamics of methyltrioctylammonium bis(trifluoromethylsulfonyl)imide[m3oa][ntf2] over a broad temperature range using broadband dielectricspectroscopy, depolarized dynamic light scattering (DDLS), rheology,and pulsed field gradient nuclear magnetic resonance. We demonstratethat the low level of ionic conductivity in this material is due tothe combined effects of reduced ion mobility as well as reduced freeion concentration relative to other types of ILs. Furthermore, detailedanalysis of the DDLS spectra reveals a slow process in addition tothe structural α relaxation that we attribute to reorientationalmotion of alkyl aggregates. These findings indicate that hydrophobicaggregation strongly influences the charge transport mechanism ofaprotic ammonium ionic liquids with long aliphatic side chains. [ABSTRACT FROM AUTHOR]

Abstract: A novel methodology for the synthesis of 2-benzoylbenzothiazoles and 2-benzylbenzothiazoles through FeCl3·6H2O catalyzed, air oxidized tandem process from commercially available 2-aminothiophenols and phenylacetaldehydes by using an ionic liquid as both reaction medium and co-catalyst was developed. [ABSTRACT FROM AUTHOR]

Abstract: An efficient and environmentally benign synthesis of 1,2-allenic ketones via RuCl3-catalyzed oxidation of homopropargyl alcohols in ionic liquid with tert-butyl hydroperoxide (TBHP) as the oxidant was reported for the first time. With its reasonable efficiency and green nature, this oxidation provides a novel alternative route to 1,2-allenic ketones. [Copyright &y& Elsevier]

• A novel ionic liquid of [Bmim]Bph 4 was used as co-extractant for extraction of Li+. • The single-stage Li/Mg separation factor was higher than 2500. • Li 2 CO 3 was obtained and the process flow was reduced with Na 2 CO 3 as stripping agent. • The binding capacity of TBP to metal ion followed the sequence Li+ ≫ Na+ > K+ ≈ Mg2+. • The whole extraction process with novel extraction system was green and efficient. A novel ionic liquid named 1-butyl-3-methylimidazolium tetraphenylboron ([Bmim]Bph 4) containing a stereo symmetric structure of Bph 4 - was synthesized and used as co-extractants with TBP and CH 2 BrCl as extractant and diluent for selective extraction of lithium ions from salt lake brines with high molar ratio of magnesium to lithium. The effects of extraction conditions containing molar ratio of co-extractant to lithium ion, volume percentage of TBP and O/A phase ratio on extraction performance were investigated. Under the optimal extraction conditions, the maximum separation factor of lithium to magnesium reached up to 2754 after one single-stage extraction process. After four stages of counter-current extraction process, the extraction efficiency of Li+ reached up to 99.47%. Then the washing and stripping conditions were optimized with the combination of LiCl and NaCl solution as the washing agent and Na 2 CO 3 solution as the stripping agent. After that, 10 cycles of the whole extraction experiments were carried out and the organic phase exhibited excellent reusability and stability. Since no acid and alkaline were used throughout the extraction process, the novel extraction process is greener and more environmentally friendly than the traditional solvent extraction process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel gemini-type benzimidazole ionic liquid was applied for gold(III) extraction. • Thermodynamic parameters(Δ H θ , Δ G θ and Δ S θ) were obtained from thermodynamic data. • [C 6 BIM 2 ][NTf 2 ] 2 showed excellent gold(III) extraction ability from secondary resources. • Gold(III) was stripped by CS(NH 2) 2 / HCl solution and maintained 5 cycles of extraction tests. In this study, a novel gemini-type benzimidazole ionic liquid [C 6 BIM 2 ][NTf 2 ] 2 was synthesized for efficient extract gold(III) from hydrochloric acid medium. Firstly, a series of parameters (e.g., vibrating time, the extractant concentration, acidity and salinity) were optimized and obtained the optimal extraction condition. Under this condition, the extraction efficiency can reach 98.42%, along with the distribution ratio of 186.87. Through the response surface methodology (RSM) model optimization, the amount of [C 6 BIM 2 ][NTf 2 ] 2 corresponding to different HCl concentration was determined for gold(III) extraction during actual operation. Then, verified the anion exchange mechanism with the aid of Job's method, UV–vis, FT-IR and 13C NMR. Thermodynamic parameters were calculated and implied that the extraction reaction was an exothermic and spontaneous process. Furthermore, organic phase loaded with gold(III) was easy to be completely stripped by CS(NH 2) 2 / HCl solution and its extraction ability was kept constant after 5 cycles extraction experiments. Meanwhile, [C 6 BIM 2 ][NTf 2 ] 2 has a superb ability to select gold(III) in the multi-metal solution. In general, [C 6 BIM 2 ][NTf 2 ] 2 showed distinguished selectivity and extraction ability for gold(III) from secondary resources, which was claimed to be a promising new style extractant. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structure-extraction performance relationship of ILs was systematically clarified. • ILs with lower solubility exhibited better extraction efficiency for Au(III). • The proposed structure-performance relationship demonstrated high universality. • [EB-IM][NTf 2 ] shows superior capacity (432.84 mg/g) and kinetics (1 min) for Au(III). • [EB-IM][NTf 2 ] possesses great practical application potential to e-waste. Ionic liquids (ILs) are regarded as an ideal candidate for recycling precious metals due to their green and tunable characteristics. However, the lack of understanding of structure-performance relationships still restricts the development and practical application of higher-performance ILs. Here, we aim to investigate the structure-extraction performance relationship, and develop a solvent-free extraction system for extracting gold from e-waste. The results demonstrate that the maximum loading capacity of imidazolium-based ILs follows the order of [EB-IM][NTf 2 ] (432.84 mg·g−1) > [EP-IM][NTf 2 ] (376.57 mg·g−1) > [EA-IM][NTf 2 ] (311.68 mg·g−1). The influence mechanism of substituents on extraction was examined through DFT calculation and quantitative NMR (q NMR). Our findings reveal that an increase in carbon chain length of ILs leads to a decrease in electrostatic potential (ESP) value, weaker binding energy, and reduced solubility. Remarkably, the decrease of solubility has a positive effect on improving extraction efficiency. Importantly, the proposed structure–activity relationship is universal. Moreover, [EB-IM][NTf 2 ] exhibited remarkable selectivity (β Au/Cu = 4.14 × 104, β Au/Ni = 2.46 × 103), recyclability (over 5 cycles) and good economic viability in waste SIM cards, obtaining high-purity gold with 23.78 karat. Overall, this study not only offers valuable guidance for the design of high-performance ILs, but also demonstrates the industrial prospect of ILs for recovering gold from e-waste. [ABSTRACT FROM AUTHOR]

• The structure–activity relationship between ILs and separated azeotrope is explored. • An efficient MSED for azeotrope separation using ILs mixed solvent is proposed. • The proposed process is optimized by nonlinear multi-objective optimization. • The feasibility of the established process is evaluated from multiple perspectives. Efficient recovery of isopropyl acetate and isopropanol from wastewater during esterification is important. An efficient separation process using ionic liquid mixed solvent extractive distillation (MSED) to separate azeotropic mixtures was proposed. The selectivity of 169 ionic liquids was calculated based on the COSMO–segment activity coefficient model for prescreening ionic liquids. The influence of the structure of the ionic liquids on the separation performance was further explored through molecular dynamics to determine 1-ethyl-3-methylimidazole acetate ([EMIM][AC]) as the best solvent. The vapor–liquid equilibrium of the system under the influence of [EMIM][AC] was measured to verify the model used for the calculation. A multi-objective genetic algorithm was used for optimizing the process parameters with the total annual cost (TAC) and gas emission as objective functions. An energy-saving heat-pump-assisted heat-integrated extractive distillation (HPHIED) process was proposed to realize heat recovery in MSED. The results showed that the TAC and gas emissions of MSED were 26.83% and 25.32%, respectively, lower than those of the single-organic solvent extractive distillation process. The TAC and gas emissions of HPHIED process were 11.02% and 35.83%, respectively, lower than those of MSED. [ABSTRACT FROM AUTHOR]

Schematic diagram of extraction process for Nd(III). [Display omitted] • The novel type carboxylic acid ILs were synthesized for recovering Nd(III). • The ILs get rid of the dependence on diluent in the extraction process. • The ILs solve the emulsification problem caused by traditional extractant. • The stripping acidity is low, which can reduce the production cost. • The ILs have strong circulating regeneration capacity. The development of an environmentally friendly extractant for selective recovery of rare earth elements is critical but still faces significant challenges. Two low viscosity carboxylic acid based ionic liquids [A336][BTA] and [A336][OTA] were synthesized for selective extraction of Nd(III) from waste NdFeB magnets. First, the extraction behaviors of two kinds of ionic liquids were compared under different conditions, such as time, pH value of aqueous phase, dosage of ionic liquids, and concentration of salting-out agent. The optimal extraction condition of [A336][OTA] was optimized by response surface methodology, and the extraction efficiency reached 99.1%. The extraction mechanism was proposed as ion association by UV–Vis spectrum, IR spectrum and 1H NMR, and was supported from that perspective of quantum chemical calculation. The extraction thermodynamics, kinetics and isothermal model were studied in detail. [A336][OTA] maintained an extraction efficiency of 95.6% even after seven cycles. The extractant shows good selective separation performance in waste NdFeB magnets, and is an extractant with good application prospect. This work has provided an environmentally friendly extractant for the recovery of Nd(III) from waste NdFeB magnets. [ABSTRACT FROM AUTHOR]