Dongli Zhang

Enrichment of Aromatic Compounds Using Ionic Liquid and Ionic Liquid-Based Aqueous Biphasic Systems

Both hydrophibic [C8mim][PF6] and [C4mim]Cl/(K2CO3, K2HPO4 or K3PO4) aqueous biphasic system (ABS) were employed for the enrichment of aromatic compounds including nitrobenzene, 4-nitrophenol, phenol and aniline from aqueous solutions. In [C8mim][PF6] enrichment system, the distribution ratio (D) of nitrobenzene and aniline increase with the increasing of pH values of aqueous phase from 2 to 8, but there is no obvious change for 4-nitrophenol and phenol. And the D values of the aromatic compounds decrease with the phase ratio change from 1/5 to 1/30 (IL phase volume/aqueous phase volume). In [C4mim]Cl/(K2CO3, K2HPO4 or K3PO4), the distribution ratio increase with the increasing of the salts concentrations. The distribution ratio order in [C8mim][PF6] and [C4mim]Cl/kosmotropic salt ABS is nitrobenzene > phenol > aniline > 4-nitrophenol. It is expected that these results are promising for the removal of the aromatic compounds from water, especially for sample enrichment in analytical science.

Separation of ternary systems of hydrophilic ionic liquid with miscible organic compounds by RPLC with refractive index detection

A rapid and simple analytical method was developed for the simultaneous and quantitative determination and separation of hydrophilic imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl; 1-hexyl-3-methylimidazolium chloride, [C(6)mim]Cl; 1-octyl-3-methylimidazolium chloride, [C(8)mim]Cl; 1-allyl-3-methylimidazolium chloride, [Amim]Cl; or 1-allyl-3-methylimidazolium bromide, [Amim]Br) with miscible ethyl acetate and EtOH and their mixtures using reverse phase liquid chromatography coupled with refractive index detection (RPLC-RI). The influence of 60 to 100% (volume percentage) methanol in the mobile phase on the IL systems ([C(4)mim]Cl, [C(6)mim]Cl, [C(8)mim]Cl, [Amim]Br, or [Amim]Cl)-ethyl acetate-EtOH was investigated. The optimum mobile phase for the system [C(8)mim]Cl-ethyl acetate-EtOH, [C(4)mim]Cl-ethyl acetate-EtOH, [Amim]Br-ethyl acetate-EtOH and [Amim]Cl-ethyl acetate-EtOH was methanol/water (60:40, v/v), and methanol/water (70:30, v/v) for [C(6)mim]Cl-ethyl acetate-EtOH. Under optimum mobile phase conditions for each system, the RSD of the retention time ranged from 0.02 to 0.04%, and the RSDs of the peak area percent ranged from 0.23 to 1.85%, which showed good reproducibility of the RPLC-RI method. The RPLC-RI method can determine IL, ethyl acetate, and EtOH simultaneously in 5 min, and the analytes, especially IL, can be eluted completely. The results show that the RPLC-RI method can be used to separate and determine ILs in mixtures with organic compounds simultaneously and quantitatively.

Kinetics of Cerium(IV) and Fluoride Extraction from Sulfuric Solutions Using Bifunctional Ionic Liquid Extractant (Bif-ILE) [A336][P204]

Abstract The extraction kinetics of Ce(IV) and Ce(IV)-F − mixture systems from sulfuric solutions to n -heptane solution containing Bif-ILE [A336][P204] ([trialkylmethylammonium][di-2-ethylhewanxylphosphinate]) with a constant interfacial area cell with laminar flow were studied, just to elucidate the extraction mechanism and the mass transfer models. The data were analyzed in terms of pseudo-first-order constants. The effects of stirring speed, specific interfacial area and temperature on the extraction rate in both systems were discussed, suggesting that the extractions were mixed bulk phases-interfacial control process. Supported by the experimental data, the corresponding rate equations for Ce(IV) extraction system and Ce(IV)–F − mixture extraction system were obtained. The experimental results indicated the rate-controlling step. The kinetics model was deduced from the rate-controlling step and consistent with the rate equation.

Applying Aqueous Biphasic Systems for Partitioning N-Methylimidazolium Grafted Merrifield Resin Microparticles

Abstract The partition behavior of Merrifield resin and two derivatives, RCl and RPF6, has been investigated in a variety of aqueous biphasic systems (ABS). The composition of ABS, different anions of the resins, and the graft ratio were found to be important for controlling the partition behavior of Merrifield resin, RCl, and RPF6 in three types of ABS: PEG-4000/Dextran-20000, PEG-4000/K2CO3, and C4mimCl/K2CO3. It was found that a 10.86% graft ratio of RCl showed a satisfactory separation for the Merrifield resins and N-methylimidazolium grafted Merrifield resins in PEG-4000/Dextran-20000 ABS. It was speculated that RCl or RPF6 has a strong interaction with Dextan-20000 and [C4mim]Cl, but very weak interaction with PEG-4000. Therefore, it was likely that the N-methylimidazolium grafted Merrifield resin was partitioned to the bottom Dextran-rich phase.