Shiping Hu

Liquid-liquid equilibrium of novel aqueous two-phase systems and evaluation of salting-out abilities of salts

AbstractBinodal data are beneficial to the design of aqueous two-phase extraction and the establishment of thermodynamic models. For the 2-propanol + Li2SO4/Na2SO4/ (NH4)2SO4/K3PO4 + water systems and 1-propanol + K3PO4/K3C6H5O7/(NH4)3C6H5O7 + water systems, binodal data were determined at 298.15 K. The binodal data were correlated by a theoretical equation on the basis of statistical geometry. The salting-out abilities of salts and the phase-separation abilities of alcohols were evaluated by the effective excluded volume of salt and the binodal curves plotted in molality. A simple Hofmeister series of cations and anions were obtained. The organic salt, K3C6H5O7, shows as high a salting-out ability as K3PO4.

Application of Water-Miscible Alcohol-Based Aqueous Two-Phase Systems for Extraction of Dyes

The water-miscible alcohols (ethanol, 1-propanpol, 2-propanol) were used to form aqueous two-phase systems with K2HPO4 and Na2HPO4. Meanwhile, the organic citrates were also investigated as the phase-separation salts. The effects of the types and concentrations of phase-forming substances as well as temperature on the formation of aqueous two-phase systems were discussed. The alcohol (ethanol, 1-propanpol, 2-propanol)–salt (K2HPO4, K3C6H5O7, (NH4)3C6H5O7) aqueous two-phase systems were used to extract Rhodamine B and methyl orange in aqueous solution. It proved that the water-miscible alcohol–salt (inorganic salt, organic salt) aqueous two-phase systems can be both used to extract hydrophilic targets directly without adding any reaction reagents. The aqueous two-phase extraction process was also discussed.

Preconcentration and separation of trace acetylspiramycin in environmental samples by use of ionic liquid-(NH 4 ) 2 SO 4 aqueous two-phase flotation system

Ionic liquid aqueous two-phase flotation (ILATPF) consisting of ionic liquid aqueous two-phase system (ILATPS) and solvent sublation (SS), which is a novel, non-toxic and green sample pretreatment technique coupled with molecular fluorescence spectrophotometry, was developed for the simultaneous separation, enrichment and rapid analysis of acetylspiramycin. In this ILATPF system of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4)/(NH4)2SO4, the effects of the solution pH, condition for phase separation, sublation time and gas flow rate were investigated and discussed in details, and the optimal conditions for ILATPF were obtained. Under the optimum conditions, this method was successfully applied to analysis of acetylspiramycin in environmental samples with the recovery of 85.8-90.4%, the detection limit of 0.04 μg/mL, and the relative standard deviation of 4 μg/mL for 10 parallel determination was lower than 0.33%. This method showed to be promising for separation and enrichment of trace acetylspiramycin as well as other substances in the environment.

Preconcentration and separation of trace roxithromycin by [Bmim]BF 4 - Na 2 CO 3 Aqueous two-phase flotation system

Combining solvent sublation with ionic liquid aqueous two-phase extraction (ILATPE), ionic liquid aqueous two-phase flotation (ILATPF) was proposed for preconcentration and separation of antibiotics in environment. The new technique was applied to preconcentrate and separate trace roxithromycin (ROX) in the environment using 1-butyl-3-methylimidazolium-tetrafluoroborate ([Bmim]BF4) ionic liquid as a green sublation solvent prior to molecular fluorescence spectrometry determination. Several factors affecting the extraction efficiency containing pH, conditions for phase separation, sublation time and gas flow rate were investigated and discussed in detail. The determination of ROX from practical samples offered satisfying extraction efficiency under the optimal conditions. The limit of detection (LOD) was 0.04 μg mL-1 and the relative standard deviation of 0.4 μg mL-1 ROX for 10 parallel determinations was lower than 0.77%. The concentration multiple of this method was 22.25 which was much larger than that of ILATPE.