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Abstract: As an effective extraction method, aqueous two-phase extraction systems based on imidazolium ionic liquids have been used, in this work, to extract proteins of bovine serum albumin, trypsin, cytochrome c and γ-globulins. Effects of the ionic liquids concentration, pH value, and temperature of the systems on the extraction efficiencies have been investigated. Experimental results show that 75–100% of the proteins could be extracted into the ionic liquid-rich phase in a single-step extraction. The extraction efficiency of cytochrome c was changed slightly with the increase of pH values. Extraction efficiencies of the proteins were found to increase with increasing temperature and increasing alkyl chain length of cation of the ionic liquids. Thermodynamic studies indicated that hydrophobic interactions were the main driving force, although electrostatic interactions and salting-out effects were also important for the transfer of the proteins. Importantly, conformation of the proteins was not affected after extraction into the upper ionic liquid-rich phase as determined by UV–visible (UV–vis) and Fourier transform infrared (FT-IR) spectroscopy of the proteins. The enzyme activity of native trypsin and the trypsin in ionic liquids was determined using N-α-benzoyl-l-arginine ethyl ester as a substrate. This novel process is suggested to have important applications for the separation of proteins. [Copyright &y& Elsevier]

[Display omitted] • Hybrid materials with photothermal conversion performance were prepared for low-energy desorption of NH 3. • Temperature of rGO@MOF-303(Al)-8% could be raised to about 75 °C in 10 min. • About 68% of NH 3 could be effectively desorbed from the adsorbent in 2-hour irradiation. • Excellent desorption performance of NH 3 under sunlight irradiation is attributed to the rapid temperature rise of the adsorbent. The capture, storage and release of NH 3 play a pivotal role in sustainable energy applications. However, to simultaneously achieve high adsorption capacity and low energy desorption remains a challenge. In this work, a novel class of hybrid materials with photothermal conversion performance have been developed by doping redox graphene and metal–organic framework of MOF-303(Al). It is found that the optimized rGO@MOF-303(Al)-8% exhibits high NH 3 uptake (17.0 mmol g−1) at 25.0 °C and 1.0 bar and exceptional photothermal conversion performance. Under the irradiation of simulated sunlight, its temperature can be raised to about 75 °C in 10 min. Even under direct natural sunlight irradiation, a stable equilibrium temperature of 53 °C may be achieved. Based on this excellent photothermal conversion performance, we investigated the desorption behavior of ammonia under visible light irradiation for the first time. We found that due to the breakdown of hydrogen bonds of NH 3 and N-N, N–H sites of rGO@MOF-303(Al)-8% caused by the rapid rise of temperature, approximately 68% of NH 3 could be effectively desorbed in 2-hour irradiation under ambient conditions. In addition, the optimized adsorbent demonstrated remarkable cycling stability. After undergoing 10 cycles, high adsorption capacity and efficient light-induced desorption of NH 3 were still maintained Thus, the present study provides a novel concept for high-capacity adsorption and low-energy desorption of NH 3 and other industrial gases. [ABSTRACT FROM AUTHOR]

It is always difficult to separate scandium from yttrium and lanthanides due to their similar physicochemical properties. In this work, a selective separation strategy for Sc (III) from yttrium and lanthanides in aqueous solution was developed by using ionic liquids 1-alkylcarboxylic acid-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([(CH 2 ) n COOHmin][Tf 2 N]) (n = 3, 5, 7) as extractants and 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C n mim][Tf 2 N]) (n = 4, 6, 8, 10) ionic liquids as diluents. The extraction parameters such as phase valume ratio, equilibrium time, pH value of the aqueous phase, alkyl chain length of the extractants and diluents, and system temperature were investigated systematically. It was shown that the extraction efficiency of Sc (III) increased with the increase of aqueous phase pH value, and was as high as 99.5% at pH 4.2. Sc (III) could be extracted selectively from yttrium and lanthanides by simple tuning of pH value of the aqueous phase, and the separation factor was 10 3 . After the extraction, stripping of Sc (III) from the ionic liquids was attempted by using dilute aqueous HNO 3 . In addition, an ion exchange mechanism of the proton of extractants and the cation of the diluents was proposed from a series of control experiments. Since both the proton of the extractants and cation of the diluents participated in the extraction process, amount of the ionic liquids transferred to water phase can be greatly reduced compared with the cation exchange based metal extraction using only ionic liquid extractants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Al-based MOFs with different number of active sites were developed for efficient adsorption and selective separation of CO 2. • MOF-303(Al) with multiple adsorption sites exhabited a high CO 2 capacity and selectivity of CO 2 to N 2 and CH 4. • MOF-303(Al) can be recycled more than 50 times by a energy-saving desorption process. • Multiple sites interactions of CO 2 with MOF-303(Al) is the key driven force for the adsorption and selective separation. Efficient capture and selective separation of CO 2 is of great significance for alleviating the greenhouse effect. However, it is still a challenge to achieve efficient, reversible and selective capture of CO 2. Here, stable Al-based MOFs with multiple adsorption sites were constructed for capture and selective separation CO 2. It was found that MOF-303(Al) with multiple active sites (μ-OH, N-H, N-N and H-C) demonstrated a high CO 2 capacity of 5.1 mmol/g, and can be recycled for more than 50 times. Moreover, MOF-303(Al) shows excellent selective separation performance of CO 2 from CO 2 /CH 4 and CO 2 /N 2 mixtures, which could be used as a potential material for natural gas purification. Mechanism results revealed that the excellent CO 2 adsorption and selective separation performance is arose from the multiple adsorption sites (μ-OH, N-H, N-N and C-H) of MOF-303(Al), where the contribution of μ-OH and N-H adsorption sites are higher than that of N-N and H-C sites. [ABSTRACT FROM AUTHOR]

Phenolic compounds are an important class of compounds for organic chemical industry. In their traditional production processes, strong acid and base have to be used for the separation of phenolic compounds from oils, which often causes serious environmental problems. In this work, choline derivative salts [N 1,1, n C 2 OH]Cl ( n = 1, 4, 6, 8) have been used as new extractants for the separation of 26 kinds of phenolic compounds from model oil (toluene) by forming deep eutectic solvents (DESs). It is found that only 16 kinds of phenolic compounds can be removed from toluene with single-step removal efficiency from 28.1% to 94.7%, strongly depending on the chemical structure of phenolic compounds. The nature, position and number of substituent groups in the phenolic compounds have a great effect on their removal efficiency. Far infrared spectroscopy and density functional theory calculations indicate that hydrogen bonds formed between –OH of the phenolic compounds and anion of the choline derivative salts is the main driving force for such DES-based separation. The correlation observed experimentally between structure of phenolic compounds and their removal efficiencies has been discussed from hydrogen bonding in DESs, electrostatic interaction of cation and anion of the choline salts, and solvation of the phenolic compounds and choline salts in the oil. [ABSTRACT FROM AUTHOR]

Carboxyl functional poly(ionic liquid)s@MOF composites were proposed as a universal adsorption platform to efficiently remove metal ions from water. [Display omitted] • Carboxyl functional ionic liquids guest molecules were incorporated into porous MOF host molecules through in situ polymerization. • Exposing more active sites is beneficial to capture metal ions. • Poly(ionic liquid)s@MOFs exhibit excellent adsorption capacity and recyclability due to the synergistic effect. • The coordination and electrostatic interaction between the carboxyl group and metal ions are the main adsorption mechanism. • This study proposes a new strategy for fabrication functional porous materials to remove metal ions with remarkable efficiency. Development of porous adsorption materials tethered with functional groups was favorable to establish a more efficient, stable and broad-spectrum metal ions removal strategy from water. In this work, carboxyl functional poly(ionic liquid)s@MOF composites were prepared through in situ polymerization of ILs monomers inside MOF pores. Their thermophysical property, structure and morphology were characterized by different techniques. These PILs@MOF composites were proposed as universal and efficient adsorbents to remove selected rare earth metal ions (La3+, Sm3+, Nd3+) and heavy metal ions (Pb2+, Cd2+) from water medium. Effect of pH value and composite dosage on the adsorption efficiency were studied in detail. The optimized adsorption efficiency as high as 99.8 % could be found for the selected metal ions by PIL@MIL-101. In addition, the isotherms, kinetics and thermodynamic parameters of the adsorption process were also determined, and these results imply that the Langmuir model and pseudo-second-order model fitted well with the experimental data. Thermodynamic parameters revealed spontaneous and exothermic nature of the adsorption process. A plausible mechanism for the adsorption process was suggested by the electrostatic interaction and coordination between the carboxyl group and metal ions with the aid of FTIR and XPS measurements. Finally, recycling experiments were performed to demonstrate the recyclability and stability of PIL@MOF composites undergoes at least five adsorption–desorption runs. The current research presented a series of poly(ionic liquid)s@MOF composites as a universal adsorption platform that demonstrated great potential for removing metal ions with remarkable efficiency. [ABSTRACT FROM AUTHOR]

Abstract: It has been reported that ionic liquids (ILs) are commonly toxic in nature, and thus the removal of ILs in various environmental systems would be of great significance. In this work, an ultrasonic irradiation and zero-valent iron activated carbon (ZVI/AC) micro-electrolysis system was applied to degradation of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) residues in water. The experimental conditions were optimized, and the degradation processes were investigated by using UV, HPLC and GC–MS techniques. It was found that more than 95% of [C4mim]Cl could be degraded in aqueous solution and 81% of [C4mim]Cl could be mineralized within 110min, and the degradation could be described by a pseudo-first-order kinetics. The presence of hydroxyl radical scavenger can greatly reduce the reaction rate but could not prevent degradation of [C4mim]Cl. GC–MS analyses demonstrated that this degradation led to the formation of 1-butyl-3-methyl-2,4,5-trioxoimidazolidine, 1-butyl-3-methylurea and N-butylformamide. On the basis of these intermediates, degradation pathway was also suggested. These results indicate that ZVI/AC micro-electrolysis with ultrasonic irradiation degradation could serve as an efficient treatment technology for removing [C4mim]Cl from wastewater. [Copyright &y& Elsevier]

Abstract: In this paper, investigations have been carried out to determine the suitability of imidazolium-based ionic liquids (ILs), 1-methyl-3-alkylimidazolium hexafluorophosphate [C n mim][PF6] (n =4, 6, 8) and 1-methy-3-alkylimidazolium tetrafluoroborate [C n mim][BF4] (n =6, 8), in replacing volatile organic solvents for liquid–liquid extraction of selected endocrine-disrupting phenols from aqueous solutions. New experimental data have been reported for the extraction of phenol, bisphenol A, pentachlorophenol, 4-octylphenol and 4-nonylphenol by the ILs. The results showed that distribution ratios of the endocrine-disrupting phenols were influenced significantly by pH of the aqueous phase, nature of the ILs, chemical structure of the phenols, and the presence of some salts in aqueous solutions. It was found that in the range of pH <7, most of the phenols were extracted quantitatively from aqueous solution into the ILs. The selective separation of some of the phenols from their binary mixtures was also investigated, and the possible driven forces for the extraction were discussed based on the hydrogen-bonding and hydrophobic interactions between the ILs and the phenols. It is expected that these results are promising for the liquid–liquid extraction, separation and preconcentration of endocrine-disrupting phenols in analytical science and related industrial process. [Copyright &y& Elsevier]

Alkanolamines/phenols DESs exhibit UCST-type phase behavior in water and have been applied for selective separation of aromatic amino acids from water. [Display omitted] • Temperature-switchable DESs are used as novel extraction solvents. • Aromatic amino acids can be selectively separated by using UCST-type DESs. • The separation factor is about 20 times that in ionic liquids extraction solvents. Amino acids are vital compounds in animal and human nutrition. However, it is still a great challenge to develop a cost-effective process for selective separation of amino acids. In the present study, a class of deep eutectic solvents (DESs) with short-chain alkanolamines as hydrogen bond acceptors (HBAs) and phenolic compounds as hydrogen bond donors (HBDs) have been explored for selective separation of aromatic amino acids for the first time. It is found that these DESs exhibit upper critical solution temperature (UCST)-type phase behavior in water, and their phase transition temperature is related with the pK a values of HBAs and HBDs as well as the hydrophobicity of HBDs. The UCST-type phase separation process is investigated by dynamic light scattering (DLS), FT-IR spectroscopy and temperature-variable 1H NMR in details, and the stability of the DESs in water is also examined. Interestingly, these UCST-type DESs/water systems are applicable to selective separation of aromatic amino acids. The separation factor between L-tryptophan and L-tyrosine as well as between L-tryptophan and L-phenylalanine can reach up to 476.1 and 87.9, respectively, which is about 20 and 19 times that reported in ionic liquids-based extraction solvents. [ABSTRACT FROM AUTHOR]