Deqian Li

The inner synergistic effect of bifunctional ionic liquid extractant for solvent extraction

The inner synergistic effect of bifunctional ionic liquid extractant (Bif-ILE) for solvent extraction is reported for the first time using [tricaprylmethylammonium][di-2-ethylhexylphosphinate] ([A336][P204]) as n extractant for Eu(III), which can be attributed to better stability and hydrophobicity of the complex formed by [A336][P204] with Eu(III). Some other Bif-ILEs are also found to have the similar inner synergistic effect. Distribution coefficient, stripping property and extraction mechanism of the novel extraction protocol are discussed in this report. The study contributes towards acquiring a new understanding of synergistic extraction and task specific ionic liquid (TSIL), furthermore, providing a positive influence on their potential application in analytical chemistry.

Application and Perspective of Ionic Liquids on Rare Earths Green Separation

This review summarizes recent applications of ionic liquids (ILs) as ‘green’ solvents and extractants in the extraction and separation of Rare Earths (REs), which are widely used in a variety of high-tech products in mining, separation, and smelting can greatly damage the environment. Conventional imidazolium-based ILs as diluents are more active than non-coordinating solvents such as kerosene and n-heptane in the extraction of REs including the co-existing thorium. Imidazolium cations can be involved in REs cation exchange or in forming new complexes with REs(III) ions. Quaternary ammonium- and phosphonium-based ILs with functional anions could be considered as bifunctional IL extractants (Bif-ILEs) for the separation of REs due to their following properties: the capacity to undergo facile synthesis route, high extraction ability and selectivity, low acid-base consumption, and easy stripping. The inner synergistic neutral complex extraction of Bif-ILEs will effectively avoid the production of ammonia-nitrogen or high content of Na+ or Ca2+ in wastewater, which is partly caused by the “saponification” of acidity extractant, such as P507, during the REs industrial separation process. The large amount of wastewater production must be prohibited because of “Emission Standards of Pollutants from Rare Earths Industry” promulgated by Chinas Ministry of Environment Protection (MOP) in 2011. Serving as extractants, additives, and templates, ILs are likewise used in the preparation of functionalized adsorption materials (i.e., sol-gel silica, Amberlite XAD series resins, IL modified Merrifield resin). These adsorption materials also show high efficiency in the enrichment of dilute leach liquor of the weathered crust elution-deposited REs ore and the enhanced separation of high-value adding heavy REs. The huge environmental challenges from highly polluted REs hydrometallurgy in China require the greener separation technique to solve these issues, and the novel ILs-based separation materials and techniques in both liquid/liquid and liquid/solid extraction and separation of various REs resources are expected to demonstrate the potential practical applications in the future.

Separation of cobalt and nickel using inner synergistic extraction from bifunctional ionic liquid extractant (Bif-ILE)

The inner synergistic extraction of [tricaprylmethylammonium][sec-octylphenoxy acetate] ([A336][CA-12]) is studied for cobalt and nickel separation. Distribution ratios of [A336][CA-12] for Co(2+) or Ni(2+) are by far higher than those of tricaprylmethylammonium sulfate ([A336](2)SO(4)), sec-octylphenoxy acetic acid (CA-12), mixture of [A336](2)SO(4) and CA-12 at the acidities from 1x10(-5) mol L(-1) to 1x10(-3) mol L(-1). The synergy coefficients of [A336][CA-12] for Co(2+) are higher than the synergy coefficients of [A336][CA-12] for Ni(2+), which can be used for the Co(2+) and Ni(2+) separation. Some thermodynamic properties of the inner synergistic extraction using [A336][CA-12] for Co(2+) and Ni(2+) are also studied, such as influence of temperature, thermodynamic functions, extraction mechanism, separation factors and stripping properties.

Solvent extraction of Scandium(III) by Cyanex 923 and Cyanex 925

The extraction equilibria of Sc(III), Zr(IV), Ti(IV), Th(IV), Fe(III) and Lu(III) from sulphuric or hydrochloric acid media by Cyanex 923 (mixture of straight chain alkylated phosphine oxides) and Cyanex 925 (mixture of branched chain alkylated phosphine oxides) were studied at various aqueous acidities. The extractant Cyanex 923 demonstrated better scandium loading and selectivity for TI(IV). Fe(III) and Lu(III) than Cyanex 925. The effects of extractant concentration on the extractions of sulphuric acid and Sc(III) by Cyanex 923 were examined. The stoichiometries of the extraction reactions were postulated based on slope analysis. The experimental results indicate that Cyanex 923 can be employed to recover scandium directly from the hydrolytic mother solution arising from TiO2 production via the sulphate process. The parameters studied were scandium loading capacity, phase ratio, concentrations of Ti(IV) scrubbing and Sc(III) stripping agents. A new solvent extraction technology of scandium recovery was developed. The purity of the final Sc(III) product is above 95% with a yield > 94%

Synergistic Extraction and Separation of Heavy Lanthanide by Mixtures of Bis(2,4,4‐trimethylpentyl)phosphinic Acid and 2‐Ethylhexyl Phosphinic Acid Mono‐2‐Ethylhexyl Ester

Abstract The extraction of Yb3+ from chloride solution has been studied using mixtures of bis(2,4,4‐trimethylpentyl)phosphinic acid (Cyanex272) and 2‐ethylhexyl phosphinic acid mono‐2‐ethylhexl ester (P507). The results show that Yb3+ is extracted into heptane as YbA3(HA)3 with Cyanex272, YbL3(HL)3 with P507, and YbA2L4H3 with synergistic mixture. The equilibrium constants, formation constants, and thermodynamic functions have been determined. Extraction mechanism and extraction process are also proposed. The extraction of heavy lanthanide ions by mixtures of Cyanex272 and P507 is studied and the possibility of separating heavy rare earth ions is discussed.

Kinetics of Cerium(IV) Extraction from H2SO4–HF Medium with Cyanex 923

Studies of the extraction kinetics of cerium(IV) from H(2)SO(4)-HF solutions with Cyanex 923 in n-heptane have been carried out using a constant interfacial area cell with laminar flow. The experimental hydrodynamic conditions were chosen so that the contribution of diffusion to the measured rate of reaction was minimized. The data were analyzed in terms of pseudo-first order constants. The results were compared with those of the system without HF. It was concluded that the addition of HF reduces the activation energy for the forward rate from 46.2 to 36.5 kJ mol(-1) while it has an opposite effect on the activation energy for the reverse process(the activation energy increased from 23.3 to 90.8 kJ mol(-1)). Thus, HF can accelerate the rate of cerium(IV) extraction. At the same time, the extraction rate is controlled by a mixed chemical reaction-diffusion rather than by a chemical reaction alone. A rate equation has also been obtained.

Two MnII2LnIII4 (Ln = Gd, Eu) hexanuclear compounds of p-tert-butylsulfinylcalix[4]arene

Two 3d-4f heterometallic compounds of p-tert-butylsulfinylcalix[4]arene were synthesized by the solvothermal method and characterized by some hinged double-dumbbell-like subunits in which two perpendicular dumbbell entities were constructed by an in-between isosceles triangle Mn(II)Ln(III)(2), and two tail-to-tail calixarene molecules, and hinged by the lanthanide-sulfinyl group bonding. The magnetic properties of the title compounds were examined.

Synergistic extraction of lanthanum(III) from chloride medium by mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 and triisobutylphosphine sulphide

Abstract The synergistic effect of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 (HPMBP) and triisobutylphosphine sulphide (TIBPS, B) is investigated in the extraction of lanthanum(III) from chloride solution. Lanthanum(III) is extracted by the mixture as LaCl 2 ·PMBP·B 0.5 instead of La(PMBP) 3 ·(HPMBP) which is extracted by HPMBP alone. The equilibrium constants and thermodynamic functions such as Δ G , Δ H and Δ S are determined. The extraction of other rare earth ions by mixtures of HPMBP and TIBPS is also studied and the possibility of separating rare earth ions is discussed.

A Unique Mn2Gd2 Tetranuclear Compound of p-tert-Butylthiacalix[4]arene

A calixarene complex with tetragonal Mn(II 2Gd(III)2 tetranuclear units was synthesized in solvothermal conditions, where the addition of a small amount of water was crucial for the formation of the target compound. In the structure, two tail-to-tail p-tert-butylthiacalixarenes are located in a C-shaped mode with a dihedral angle of 14.29 degrees but not in the conventional antiparallel arrangement and form a sandwich-like subunit with an in-between Mn2Gd2 unit. Both calixarenes assume similar cone shapes of C2v symmetry but are pinched to different extents. The extended structure is constructed by supramolecular stacking of the sandwich-like units with the interstices filled by the solvent. The magnetic property of the title compound has been examined.

Assembly of ‘discrete’ (H2O)16water clusters within a supramolecular compound of calixarene

A ‘discrete’ (H2O)16cluster, featuring four basic cyclic nine-membered rings and a twelve-membered ring, illustrates a new mode of supramolecular association of water molecules.