Application of Poly(ethylene glycol)-based Aqueous Biphasic Systems as Reaction and Reactive Extraction Media

The Research and Mechanism of Extracting Vitamin B6 Using Aqueous Two-Phase Systems

The aim of this work is to investigate the quaternary systems which contain (polyethylene glycol/isopropyl alcohol) + ethanol + salt (Na2SO4/Na2CO3) + water to understand their liquid-liquid equilibrium (LLE) and salting-out ability and apply them to definite uses. For this purpose, phase diagrams and liquid-liquid equilibrium (LLE) data of the investigated quaternary systems were experimentally determined at 308.15, 318.15, and 328.15 K. Binodal curves were fitted to three empirical nonlinear equations, whereas tie-lines were fitted to the Setschenow-type equation and another two-parameter equation. All the models were successfully correlated with the experimental data. What is more, factors such as temperature, different organic solvent, and type of salt are studied. It was demonstrated that temperature has no influence in binodal curves and the salting-out ability follows the order Na2CO3 > Na2SO4. Finally, we chose the best system (isopropyl alcohol + ethanol + Na2CO3 + H2O) to find out the extraction efficiency when dealing with vitamin B6. The results show that when the temperature is 308.15 K and pH is 5.02, the extraction efficient can reach a top level. It serves as a theoretical basis for the extraction, separation, and purification.

One-pot oxidative cleavage of cyclic olefins for the green synthesis of dicarboxylic acids in Pickering emulsions in the presence of acid phosphate additives

Dicarboxylic acids were prepared by the oxidative cleavage of cyclic alkenes by adsorbing dodecyltrimethylammonium phosphotungstate particles and silica particles functionalized with octadecyl chains and sulfonic acid groups at the W/O interface.

Extraction in cholinium-based magnetic ionic liquid aqueous two-phase system for the determination of berberine hydrochloride in Rhizoma coptidis

A magnetic ionic liquids (MILs)-based aqueous two-phase system (MIL-ATPs) obtained by mixing with a series of inorganic salts, which involves five cholinium MILs with the piperidinyloxy radical anion is reported for the first time. Phase diagrams for the new ATPs were experimentally determined at different temperatures (298.15–318.15 K) and the liquid–liquid equilibrium data for two-phase systems were correlated according to the empirical nonlinear expression. The effects of the types of MILs, temperature and inorganic salts on the binodal curve are discussed in detail. The MIL-ATPs coupled with HPLC-UV analysis was developed in the quantitation of berberine hydrochloride in Rhizoma coptidis. Under optimal conditions, the partition coefficient of berberine hydrochloride was 127.68 with the precision values (RSD%) of 1.40% and 2.83% for intra-day (n = 6) and inter-day (n = 3), respectively. The limit of detection (LOD) and limit of quantification (LOQ) for berberine hydrochloride were 0.023 mg L⁻¹ and 0.077 mg L⁻¹, respectively. The recoveries were obtained in the acceptable range of 97.4–101.2%. Moreover, the content of berberine hydrochloride in the raw material of Rhizoma coptidis was measured as 123.95 mg g⁻¹ with this method. Finally, 99.8% MIL was recovered for cycle application after the removal of berberine hydrochloride by using D101 resin. This study provides a meaningful reference for the application of MIL-ATPs with great prospects.

Five cholinium type organic magnetic ionic liquids have been applied in ionic liquid-based aqueous two-phase systems by mixing with a series of inorganic salts, which is reported to extract berberine in quantitative analysis for the first time.

Liquid-Liquid Equilibrium Data for the Ionic Liquid N-Ethyl-Pyridinium Bromide with Several Sodium Salts and Potassium Salts

The liquid-liquid equilibrium (LLE) data for systems containing N-ethyl-pyridinium bromide ([EPy]Br), salt (Na2HPO4,K2HPO4,K2SO4,C4O6H4KNa), and water have been measured experimentally atT=298.15 K and the formations of these four aqueous two-phase systems (ATPSs) have been discussed. Also, the effective excluded volume (EEV) values obtained from the binodal models for the four systems were determined and the salting-out abilities of different salts follow the order ofK2SO4>K2HPO4>Na2HPO4>C4O6H4KNa. The solubility data were correlated by the Merchuk and other equations while the tie-line data by the Othmer-Tobias, Bancroft, two-parameter, and Setschenow-type equations. The correlation coefficients evidenced that experimental data fitted well to all these equations. These four salts were proved successfully to form ATPSs with N-ethyl-pyridinium bromide, making a significant contribution to the further study of this kind of ATPS.

Observation of poly(ethylene glycol) clusters with the chlorine anion in the gas phase under electrospray conditions

It is demonstrated herein that poly(ethylene glycol) (PEG) oligomers can form stable complexes with the chlorine anion in the gas phase as evidenced by results from electrospray ionization mass spectrometry (ESI-MS) and molecular dynamics simulation. While the formation of crown-ether-like structures by acyclic polyethers in their complexes with alkali metal cations coordinated by the ether oxygen atoms has been extensively studied, the possibility of forming 'inversed' quasi-cyclic structures able to bind a monoatomic anion has not been proved till now. We have observed the formation of stable gas-phase complexes of oligomers of PEG-400 with the Cl(-) anion experimentally by ESI-MS for the first time. It is suggested that a necessary precondition for obtaining the polyether-chlorine anion clusters is the prevention of the formation of neutral ion pairs. Molecular dynamics simulation has demonstrated the wrapping of the Cl(-) anion by the PEG chain, to stabilize the PEG(n)•Cl(-) clusters in the gas phase. The conformation of the polyether chain in such quasi-cyclic or quasi-helical complexes is 'inversed' compared with that in the complexes with cations: that is its hydrogen atoms are turned towards the central anion. Awareness of the possibility of the Cl(-) anion being trapped in quasi-cyclic PEG structures may be of practical importance when considering the intermolecular interactions of PEGs.

Extraction of trace acetylspiramycin in real aqueous environments using aqueous two-phase system of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and phosphate

The partitioning of acetylspiramycin was carried out in an aqueous two-phase system (ATPS) formed by a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoraborate, [Bmim]BF4) and NaH2PO4. This ATPS is a simple, non-toxic and effective sample pretreatment technique, which was developed for the simultaneous separation, enrichment and rapid analysis of acetylspiramycin coupled with molecular fluorescence spectrophotometry. Analysis of the liquid-liquid equilibrium of [Bmim]BF4-salt ATPS demonstrated that the salting-out ability of different salts may be related to the Gibbs energy of hydration of the ions. The effects of types of salts, concentration of NaH2PO4, and temperature were analysed. Under optimum conditions, the average extraction efficiency and partition coefficient were 90.14% and 91.1, respectively. Thermodynamic functions provide some information about the molecular mechanism involved in acetylspiramycin transfer to the top phase, suggesting an important acetylspiramycin-[Bmim]BF4 interaction. The method yielded a linear range in the concentration from 1.0 to 10.0 µg mL−1 of acetylspiramycin, and the limit of detection was 0.02 µg mL−1. This method could be successfully applied for the analysis of acetylspiramycin in lake water, river water and groundwater. The proposed extraction technique appears to be suitable as a first step for the separation of macrolide antibiotics from real aqueous environments.