•Resin was used to recover three ILs from glucose for the first time.•Adsorption, desorption and reuse of IL were all investigated in detail.•Real samples in hydrolysis and extraction validated the adsorption performance.•The purity of recovered IL was confirmed by HPLC and 1HNMR.The recycling of ionic liquids (ILs) is an essential process to recover them from complex systems for repeated use, which is very crucial for its “green” feature. Saccharides are a kind of common coexisting constituents with ILs in many applications. The study used ion-exchange resins to recover three kinds of benzothiazolium ionic liquids from coexisting glucose. Five ion-exchange resins with different function groups and ionic form were investigated by mixing with the solution of ILs and glucose in batch. Influencing factors were also investigated in detail for adsorption of ionic liquid from glucose aqueous solution. Among them, only D001 resin showed the weak adsorption capacity for glucose. Under the optimal conditions, the maximum adsorption ratio of [HBth][CF3SO3] was 98.58%. Moreover, desorption of target ILs and reuse of resins were also investigated, and the maximum desorption ratio of [HBth][CF3SO3] was 98.6%. After the ILs were applied in the extraction of saccharides in Lycium barbarum L. and hydrolysis of pretreated bagasse cellulose, the adsorption ratio of [HBth][CF3SO3] was 91.1% and [HBth][CH3SO3] was 90.8% by the recovery method respectively.

•Bionic multi-tentacled ionic liquid sorbent was prepared for the first time.•It has excellent abilities of selective absorption as well as fine separation.•Properties, performance and mechanism were investigated comprehensively.•Bioactivity was also evaluated for the separation and had good result.For the first time, a new kind of bionic multi-tentacled ionic liquid-modified silica gel was synthesized and used as selective adsorbent in the preparative separation of tea polyphenols (TP) from green tea leaves. It was found that silica particles with polyvinyl alcohol chains modified by N-methyl imidazole proline salt (PVA·Im+·Pro−@SiO2) had the excellent performance in selective adsorption as well as fine separation for target compounds. The new adsorbent exhibited high adsorption capacity and good reusability, meanwhile the antioxidant activity of TP could be improved through its efficient enrichment. It properties and adsorption mechanism were also investigated comprehensively and compared with those reported sorbents. Finally, the preparative separation of individual catechin from crude extracts was successfully achieved on the chromatographic column packed with PVA·Im+·Pro−@SiO2 particles and four main constituents were obtained successively. The study was expected to provide a new way for the effective separation of similar bioactive compounds.Download high-res image (203KB)Download full-size image

•New method of sequential extraction based on ILs was developed at the first time.•Good selectivity was found to realize the separation of two kinds of constituents.•Related conditions and process were investigated by many methods.•The recovery of ionic liquids and products was studied and compared detailedly.In recent years, ionic liquids (ILs) have received more attentions in green extraction and separation process as a kind of novel environment-friendly solvent, and their application in the field of natural products needs to be extended. In this paper, a new method of the sequential extraction for stilbene glycoside and anthraquinones from Polygonum multiflorum was developed for the first time and different ionic liquids was used and compared. It was found two benzothiazolium ILs including [BBth][Br] and [HBth][p-TSA] had good selectivity and high efficiency. In addition, the important extraction conditions were also investigated and optimized. Compared with the traditional acid/alcohol-water extraction process, the extraction assisted by ionic liquid not only can obtain higher yield in shorter time, but also can realize the selective extraction for two different kinds of constituents with less consumption. Furthermore, the recovery of target compounds and recycling of ionic liquid were also studied and it was found that solvent extraction combined with cation-exchange resin had the ideal recovery performance.

•Liquid-liquid equilibrium data for the MIL-based ATPs at 298.15 K were measured.•Three equations were successfully applied for the binodal curve correlation.•The phase behavior was compared from binodal curves.•Three theoretical equations were successfully used to fit the tie-line data.Functionalized magnetic ionic liquids (MILs)([C2TMG][TEMPO-OSO3], [C3TMG][TEMPO-OSO3], [C4TMG][TEMPO-OSO3]) and three inorganic salts (K2HPO4/K2CO3/Na2CO3) were used to form aqueous two-phase system at 298.15 K. Three classical experienced equations were applied for the correlations of the binodal curves. All of them demonstrated satisfactory performance in data association. The binodal curves were investigated in detail. Both K2HPO4 and K2CO3 was excellent phase forming salts for all the three MILs. Both of them can meet the need of practical applications. There is a narrow biphasic region for the MIL + Na2CO3 + water system because of a relatively low solubility of salt in water. Additionally, tie-line data were experimentally obtained for the three MILs with K2HPO4 or K2CO3 at 298.15 K. Three empirical formulas including Othmer-Tobias equation, Bancroft equation together with another equation derived from binodal theory were used to fit the tie-line data. Consequently, Othmer-Tobias has shown ideal correlation performance and the reliability of our experimental tie-line data can be ensured. Hopefully, these aqueous two-phase equilibrium data should be useful in the areas of chemical separation, purification and analysis.

•A new organic magnetic ionic liquid was synthesized and characterized.•A novel method of MILATPs-HPLC was established to analysis CAP.•Satisfactory performance and ideal magnetic response were obtained.•Good microextraction ability was verified by actual water samples.A novel organic magnetic ionic liquid based on guanidinium cation was synthesized and characterized. A new method of magnetic ionic liquid aqueous two-phase system (MILATPs) coupled with high-performance liquid chromatography (HPLC) was established to preconcentrate and determine trace amount of chloramphenicol (CAP) in water environment for the first time. In the absence of volatile organic solvents, MILATPs not only has the excellent properties of rapid extraction, but also exhibits a response to an external magnetic field which can be applied to assist phase separation. The phase behavior of MILATPs was investigated and phase equilibrium data were correlated by Merchuk equation. Various influencing factors on CAP recovery were systematically investigated and optimized. Under the optimal conditions, the preconcentration factor was 147.2 with the precision values (RSD%) of 2.42% and 4.45% for intra-day (n = 6) and inter-day (n = 6), respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.14 ng mL−1 and 0.42 ng mL−1, respectively. Fine linear range of 12.25 ng mL−1–2200 ng mL−1 was obtained. Finally, the validated method was successfully applied for the analysis of CAP in some environmental waters with the recoveries for the spiked samples in the acceptable range of 94.6%–99.72%. Hopefully, MILATPs is showing great potential to promote new development in the field of extraction, separation and pretreatment of various biochemical samples.

•SiO2·Trop+·Pro− was prepared, identified and used for the first time.•SiO2·Trop+·Pro−-Cu2+ was used in enantioseparation for the first time.•The mode of ‘reuse after adsorption’ was developed and applied.•Multifunction of the material was focused for metal ions and d,l-amino acids.•Mechanism of enantioseparation was discovered by comparison experiments.Tropine-type chiral ionic liquid with proline anion was immobilized on silica gel by chemical modification method for the first time, which was proved by elemental, infrared spectrum and thermogravimetric analysis. Secondly, the performance of this kind of ionic liquid-modified silica gel was investigated in the adsorption of some metal ions, which included Cu2+, Fe3+, Mn2+ and Ni2+. Then the effects of time, initial concentration and temperature on adsorption for Cu2+ ions were studied in detail, which was followed by the further research of adsorption kinetics and thermodynamics. The adsorption could be better described by pseudo-second-order kinetics model and that the process was spontaneous, exothermic and entropy decreasing. In the mode of ‘reuse after adsorption’, the ionic liquid-modified silica gel with saturated adsorption of Cu2+ was finally used in resolution of racemic amino acids for the first time. The static experiment showed that adsorption rate of two enantiomers was obviously different. Inspired by this, the complex was packed in chromatographic column for the separation of racemic amino acids and d-enantiomers were firstly eluted by water or ethanol. Steric hindrance was found as one of key influencing factors for its effect on the stability of the complex.

•A series of new ionic liquids with tropine as cation nucleus were synthesized.•The structures of ionic liquids were characterized by 1H NMR, 13C NMR, MS, and IR.•Polarity, Brønsted acidities and the properties of thermodynamics were measured.•Association and transfer of ionic liquids in water at 298.15 K were investigated.•The influence of IL structure on its physicochemical properties was discussed.In this study, a series of new ionic liquids (ILs) with tropine as cationic nucleus and hexafluorophosphate as anion were synthesized. As two types of functional groups, aliphatic chains and benzyl with different substituents have been linked on the tropine nucleus in order to modulate the physicochemical properties of the ILs. The whole family of ILs was comprehensively identified by FT-IR, NMR and MS. Furthermore, the thermal properties of these ILs were evaluated by different scanning calorimetry (DSC) together with their melting points and enthalpy of fusion. Then the polarities of these tropine-type ILs were investigated and discussed. Resultantly, it was proved that their polarity was comparable with that of short-chain alcohols. Moreover, the Hammett function values of these involved ILs were determined to describe their Brønsted acidities. Finally, molar conductivities (Λ) of the tropine-type ILs in dilute solutions at 298.15 K were determined. The data were correlated with the Arrhenius–Ostwald model to obtain limiting molar conductivities (Λ∞) and association constants (KA). The influences of the branch chain of ILs on the ion transfer and association were also discussed. It was found that the size of cation was the main factor influencing the ion transfer. And the weak ion association of tropine-type ILs in water was proved by KA, which was less than 7 L·mol− 1.

•Ionic liquid-modified silicas were firstly used to adsorb Salvia phenolic acids.•These phenolic acids was firstly preparatively separated on SiO2·Im+·PF6− column.•Acidity of these phenolic acids was firstly determined for separation mechanism.•There are systematic characterization, investigation and instructive findings.•SiO2·Im+·PF6− shows good adsorption, desorption and reusability for phenolic acids.In this work, six kinds of different ionic liquid-modified silica were synthesized and characterized with infrared spectroscopy, thermogravimetric analysis, elemental analysis, N2 adsorption–desorption isotherms and particle size distribution. Then they were used as adsorbents for the preparative separation of water-soluble phenolic acids from Salvia militiorrhiza Bunge for the first time. The effects of various parameters including functional groups of adsorbents, adsorption time, initial concentration, solid–liquid ratio and temperature were investigated in detail. It was found that silica modified with N-methylimidazolium hexafluorophosphate (SiO2·Im+·PF6−) had most excellent adsorption capacity for target compounds, which reached 99.81 mg/g under the conditions of adsorption time of 30 min, initial sample concentration of 350 mg/L and solid–liquid ratio of 1:1 (mg/mL). Studies showed that the equilibrium data fitted well with Langmuir model of adsorption and the adsorption kinetics was more accurately described by pseudo-second-order model. Thermodynamics parameters including the change of enthalpy, entropy and Gibbs free energy were also analyzed. Furthermore, the water-soluble phenolic acids of Salvia militiorrhiza Bunge were successfully preparatively separated on the normal pressure chromatographic column packed with the SiO2·Im+·PF6− particles to obtain protocatechuic aldehyde, sodium danshensu, rosmarinic acid, lithospermic acid and salvianolic acid B successively. The separation mechanism was investigated on the basis of experimental results and the reusability of the ionic liquid-modified silica gel was also explored. This study provides an useful reference for the preparation separation of natural products and indicates that the ionic liquid-modified silica can be applied in the separation of water-soluble phenolic acids with great prospects.

Considering the possible comprehensive utilisation of bioactive constituents in the sugarcane industry, the flavonoids and anthocyanins in raw juice and various intermediate products within the sugar-making process were first analysed by HPLC-UV/DAD. The analysis was intended to reveal their distribution across the whole production chain. As their contents decreased during sugar production, a new strategy was developed and optimised to recover flavonoids and anthocyanins from raw juice, using A D141-type macroporous adsorptive resin for enrichment. The optimum process parameters were feeding with a pH value of 5.21, weight ratio of resin to crude sample of 20 (w/w), followed by adding 30% ethanol 3.57 times the column volume for anthocyanins with a flow rate of 1.69 bed volumes/h, then 100% ethanol 4.00 times the column volume for flavonoids with a flow rate of 2.36 bed volumes/h. Upon employing this method, an increase in efficiency was realised.

Isobaric vapor−liquid equilibrium (VLE) data were measured at 101.3 kPa by using an improved Rose equilibrium still for three binary systems, acetonitrile (1) + 1-propanol (2), acetonitrile (1) + dimethyl sulfoxide (DMSO) (3), and 1-propanol (2) + DMSO (3), and for one ternary system, acetonitrile (1) + 1-propanol (2) + DMSO (3). The VLE data of the binary systems were examined by thermodynamic consistency tests and satisfactorily correlated by Wilson and NRTL models. The parameters of two models obtained from the binary data were used to predict the ternary VLE data. The prediction yielded reasonable results for the ternary system.

•Ionic liquids solvents could extract flavonoids and anthocyanins simultaneously.•Sugarcane tip was found with the highest antioxidant bioactivity.•D141 macroporous resin offered the best adsorption and desorption performance.•Pseudo-first-order kinetics model was favorable for illustrating adsorption process.•Equilibrium experimental data were well-fitted to the Langmuir isotherms.The application of ionic liquids (ILs) and macroporous resins for systematic separation of flavonoids and anthocyanins from Chinese sugarcane (Saccharum sinensis Roxb.) has been studied. The results show that the 0.8 M 1-butyl-3-methylimidazolium hexafluorophosphate aqueous solution ([C4MIM] [PF6]–water) has the highest yield among all the ILs and sugarcane tip is found with highest antioxidant bioactivity. D141 resin has the best adsorption and desorption performance for flavonoids and anthocyanins. And the pseudo-first-order kinetics model is the most favorable tool for illustrating the whole adsorption process. Furthermore, the equilibrium experimental data are well-fitted to the Langmuir isotherms. The values of ΔH, ΔG and ΔS suggest that the adsorption process is exothermic and the main driving force is hydrophobic interaction. Dynamic adsorption and desorption experiments prove that the flavonoids and anthocyanins can be completely eluted with the ethanol–water (70:30, v/v) of 5 BV and lower flow rate is more benefit to desorption process.