Green and efficient extraction strategy to lithium isotope separation with double ionic liquids as the medium and ionic associated agent

The paper reported a green and efficient extraction strategy to lithium isotope separation. A 4-methyl-10-hydroxybenzoquinoline (ROH), hydrophobic ionic liquid—1,3-di(isooctyl)imidazolium hexafluorophosphate ([D(i-C₈)IM][PF₆]), and hydrophilic ionic liquid—1-butyl-3-methylimidazolium chloride (ILCl) were used as the chelating agent, extraction medium and ionic associated agent. Lithium ion (Li⁺) first reacted with ROH in strong alkali solution to produce a lithium complex anion. It then associated with IL⁺ to form the Li(RO)₂IL complex, which was rapidly extracted into the organic phase. Factors for effect on the lithium isotope separation were examined. To obtain high extraction efficiency, a saturated ROH in the [D(i-C₈)IM][PF₆] (0.3 mol l^?1), mixed aqueous solution containing 0.3 mol l^?1 lithium chloride, 1.6 mol l^?1 sodium hydroxide and 0.8 mol l^?1 ILCl and 3:1 were selected as the organic phase, aqueous phase and phase ratio (o/a). Under optimized conditions, the single-stage extraction efficiency was found to be 52 %. The saturated lithium concentration in the organic phase was up to 0.15 mol l^?1. The free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) of the extraction process were ?0.097 J mol^?1, ?14.70 J mol K^?1 and ?48.17 J mol^?1 K^?1, indicating a exothermic process. The partition coefficients of lithium will enhance with decrease of the temperature. Thus, a 25 °C of operating temperature was employed for total lithium isotope separation process. Lithium in Li(RO)₂IL was stripped by the sodium chloride of 5 mol l^?1 with a phase ratio (o/a) of 4. The lithium isotope exchange reaction in the interface between organic phase and aqueous phase reached the equilibrium within 1 min. The single-stage isotope separation factor of ⁷Li–⁶Li was up to 1.023 ± 0.002, indicating that ⁷Li was concentrated in organic phase and ⁶Li was concentrated in aqueous phase. All chemical reagents used can be well recycled. The extraction strategy offers green nature, low product cost, high efficiency and good application prospect to lithium isotope separation.     

The preparation of sol-gel materials doped with ionic liquids and trialkyl phosphine oxides for yttrium(III) uptake

A new material (IL923SGs) composed of ionic liquids and trialkyl phosphine oxides (Cyanex 923) for Y(III) uptake was prepared via a sol-gel method. The hydrophobic ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate (C₈mim⁺PF₆⁻) was used as solvent medium and pore templating material. The extraction of Y(III) by IL923SGs was mainly due to the complexation of metal ions with Cyanex 923 doped in the solid silica. Ionic liquid was stably doped into the silica gel matrix providing a diffusion medium for Cyanex 923, and this will result in higher removal efficiencies and excellent stability for metal ions separation. IL923SGs were also easily regenerated and reused in the subsequent removal of Y(III) in four cycles.     

Polymer/colloid dual-phase electrolyte membrane for rechargeable lithium batteries

In this work, a polymer/ceramic phase-separation porous membrane is first prepared from polyvinyl alcohol–polyacrylonitrile water emulsion mixed with fumed nano-SiO₂ particles by the phase inversion method. This porous membrane is then wetted by a non-aqueous Li–salt liquid electrolyte to form the polymer/colloid dual-phase electrolyte membrane. Compared to the liquid electrolyte in conventional polyolefin separator, the obtained electrolyte membrane has superior properties in high ionic conductivity (1.9 mS?cm^?1 at 30 °C), high Li⁺ transference number (0.41), high electrochemical stability (extended up to 5.0 V versus Li⁺/Li on stainless steel electrode), and good interfacial stability with lithium metal. The test cell of Li/LiCoO₂ with the electrolyte membrane as separator also shows high-rate capability and excellent cycle performance. The polymer/colloid dual-phase electrolyte membrane shows promise for application in rechargeable lithium batteries.     

Highly Efficient Diglycolamide‐Based Task‐Specific Ionic Liquids: Synthesis,Unusual Extraction Behaviour,Irradiation, and Fluorescence Studies

Two new diglycolamide‐based task‐specific ionic liquids (DGA? TSILs) were evaluated for the extraction of actinides and lanthanides from acidic feed solutions. These DGA? TSILs were capable of exceptionally high extraction of trivalent actinide ions, such as Am³⁺, and even higher extraction of the lanthanide ion, Eu³⁺ (about 5–10 fold). Dilution of the DGA? TSILs in an ionic liquid, C₄mim⁺ ? NTf₂^?, afforded reasonably high extraction ability, faster mass transfer, and more efficient stripping of the metal ion. The nature of the extracted species was studied by slope analysis, which showed that the extracted species contained one NO₃^? anion, along with the participation of two DGA? TSIL molecules. Time‐resolved laser fluorescence spectroscopy (TRLFS) analysis showed a strong complexation with no inner‐sphere water molecule in the Eu^III? DGA? TSIL complexes in the presence and absence of C₄mim⁺ ? NTf₂^? as the diluent. The very high radiolytic stability of DGA? TSIL 6 makes it one of the most‐efficient solvent systems for the extraction of actinides under acidic feed conditions.     

A further understanding of the cation exchange mechanism for the extraction of Sr2+ and Cs+ by ionic liquid

The cation exchange mechanism was further investigated during the extraction of Sr 2+ and Cs+ using the extractant dicyclo- hexano-18-crown-6 (DCH18C6) in an ionic liquid (IL)1-ethyl-3-methyimidazolium bis[(trifluoromethyl)sulfonyl]imide (C2 mimNTf2 ). The concentrations of both the cation C2 mim + and the anion NTf2 in aqueous phase were detected. The con-centration of NTf2 in the aqueous phase decreased as Sr2+ or Cs+ exchanged into the IL phase. Addition of C2 mim + or NTf2 as well as the variation of the solubility of C2 mimNTf2 influenced the extraction efficiency of Sr2+ or Cs+ .     

Kinetic and galvanostatic studies of a polymer electrolyte for lithium-ion batteries

Quaternary polymer electrolyte (PE) based on poly(acrylonitrile) (PAN), 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid (EMImBF₄), sulfolane (TMS) and lithium hexafluorophosphate salt (LiPF₆) (PAN-EMImBF₄-sulfolane-LIPF₆) was prepared by the casting technique. Obtained PE films of ca. 0.2–0.3 mm in thickness showed good mechanical properties. They were examined using scanning electron microscopy (SEM), thermogravimetry (TGA, DSC), the flammability test, electrochemical impedance spectroscopy (EIS) and galvanostatic charging/discharging. SEM images revealed a structure consisting of a polymer network (PAN) and space probably occupied by the liquid phase (LiPF₆ + EMImBF₄ + sulfolane). The polymer electrolyte in contact with an outer flame source did not ignite; it rather underwent decomposition without the formation of flammable products. Room temperature specific conductivity was ca. 2.5 mS cm^?1. The activation energy of the conding process was ca. 9.0 kJ mol^?1. Compatibility of the polymer electrolyte with metallic lithium and graphite anodes was tested applying the galvanostatic method. Charge transfer resistance for the C₆Li → Li⁺ + e^? anode processes, estimated from EIS curve, was ca. 48 Ω. The graphite anode capacity stabilizes at ca. 350 mAh g^?1 after the 30th cycle (20 mA g^?1).     

Low temperature nanostructured lithium titanates: controlling the phase composition, crystal structure and surface area

Low temperature lithium titanate compounds (i.e., Li₄Ti₅O₁₂ and Li₂TiO₃) with nanocrystalline and mesoporous structure were prepared by a straightforward aqueous particulate sol–gel route. The effect of Li:Ti molar ratio was studied on crystallisation behaviour of lithium titanates. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powders were crystallised at the low temperature of 500 °C and the short annealing time of 1 h. Moreover, it was found that Li:Ti molar ratio and annealing temperature influence the preferable orientation growth of the lithium titanate compounds. Transmission electron microscope (TEM) images showed that the average crystallite size of the powders annealed at 400 °C was in the range 2–4 nm and a gradual increase occurred up to 10 nm by heat treatment at 800 °C. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had mesoporous and nanocrystalline structure with the average grain size of 21–28 nm at 600 °C and 49–62 nm at 800 °C depending upon the Li:Ti molar ratio. Moreover, atomic force microscope (AFM) images confirmed that the lithium titanate films had columnar like morphology at 600 °C, whereas they showed hill-valley like morphology at 800 °C. Based on Brunauer–Emmett–Taylor (BET) analysis, the synthesized powders showed mesoporous structure containing pores with needle and plate shapes. The surface area of the powders was enhanced by increasing Li:Ti molar ratio and reached as high as 77 m²/g for the ratio of Li:Ti = 75:25 at 500 °C. This is one of the smallest crystallite size and the highest surface areas reported in the literature, and the materials could be used in many applications such as rechargeable lithium batteries and tritium breeding materials.     

The role of organic acids on <Superscript>226</Superscript>Ra transfer factor in corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

Enrichment of lithium isotopes by displacement chromatography on strong acid cation exchanger was investigated. Narrow particle fraction of Dowex 50 WX 2 cation exchanger having diameter of 150–200 µm and total exchange capacity of 1.31 meq mL^?1 was used as stationary phase. As a mobile phase, 1 mol L^?1 solution of ammonium nitrate solution was used. Shape and position of Li chromatographic peak, was determined by atomic emission spectroscopy (AES). Isotope ratio was estimated by ICP–MS after 1, 8 and 10 enrichment steps. Value of separation factor for ⁶Li in one step was determined to be 1.027.     

Effect of Salts (NaCl and Na2CO3) on Callus and Suspension Culture of Stevia rebaudiana for Steviol glycoside Production

Steviol glycosides are natural non-caloric sweeteners which are extracted from the leaves of Stevia rebaudiana plant. Present study deals the effect of salts (NaCl and Na₂CO₃) on callus and suspension culture of Stevia plant for steviol glycoside (SGs) production. Yellow-green and compact calli obtained from in vitro raised Stevia leaves sub-cultured on MS medium supplemented with 2.0 mg l^?1 NAA and different concentrations of NaCl (0.05–0.20 %) and Na₂CO₃ (0.0125–0.10 %) for 2 weeks, and incubated at 24?±?1 °C and 22.4 μmol m^?2 s^?1 light intensity provided by white fluorescent tubes for 16 h. Callus and suspension biomass cultured on salts showed less growth as well as browning of medium when compared with control. Quantification of SGs content in callus culture (collected on 15th day) and suspension cultures (collected at 10th and 15th days) treated with and without salts were analyzed by HPLC. It was found that abiotic stress induced by the salts increased the concentration of SGs significantly. In callus, the quantity of SGs got increased from 0.27 (control) to 1.43 and 1.57 % with 0.10 % NaCl, and 0.025 % Na₂CO₃, respectively. However, in case of suspension culture, the same concentrations of NaCl and Na₂CO₃ enhanced the SGs content from 1.36 (control) to 2.61 and 5.14 %, respectively, on the 10th day.     

Preparation and proton conductivity evaluation of a silicate gel composite doped with a metal–Schiff-base–POM-MOF

A silica gel composite (denoted as 1–SG) doped with a proton-conductive metal–Schiff-base–POM-MOF, {[Cu₃(L)₂(H₂O)₄][Cu(DMF)₄(SiW₁₂O₄₀)]·9H₂O} _n (1) (where L is N, N′-bis[1-(2-methoxyphenol-6-yl)-methylidene] hydrazine hydrate, DMF is dimethyl formamide, POM-MOF is polyoxometalates-based metal–organic framework), was prepared by sol–gel method. The structure of as-synthesized 1–SG was confirmed by infrared spectrometry and X-ray powder diffraction, and its proton conductivity was calculated based on electrochemical impedance spectroscopic measurement. It was found that the structural characteristics of complex 1 are retained successfully in the silica gel skeleton of as-prepared 1–SG. Besides, though 1–SG contains just 6.25 wt% complex 1, it exhibits good proton conductivities of as much as 1.51 × 10^?3–1.26 × 10^?2 S cm^?1 in the temperature range of 25–100 °C under a relative humidity of 98 %; and in particular, it shows better proton conductivity than both complex 1 and silica gel at the same conditions, due to the presence of a large number of micropores and mesopores filled with “liquid”.     

Enhanced lithium-ion intercalation and conduction of transparent tantalum oxide films by lithium addition with an atmospheric pressure plasma jet

An investigation is conducted on enhancing lithium-ion intercalation and conduction performance of transparent organo tantalum oxide (TaO _y C _z ) films, by addition of lithium via a fast co-synthesis onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates at the short exposed durations of 33–34 s, using an atmospheric pressure plasma jet (APPJ) at various mixed concentrations of tantalum ethoxide [Ta(OC₂H₅)₅] and lithium tert-butoxide [(CH₃)₃COLi] precursors. Transparent organo-lithiated tantalum oxide (Li _x TaO _y C _z ) films expose noteworthy Li⁺ ion intercalation and conduction performance for 200 cycles of reversible Li⁺ ion intercalation and deintercalation in a 1 M LiClO₄-propylene carbonate electrolyte, by switching measurements with a potential sweep from ?1.25 to 1.25 V at a scan rate of 50 mV/s and a potential step at ?1.25 and 1.25 V, even after being bent 360° around a 2.5-cm diameter rod for 1000 cycles. The Li⁺ ionic diffusion coefficient and conductivity of 6.2?×?10^?10 cm²/s and 6.0?×?10^?11 S/cm for TaO _y C _z films are greatly progressed of up to 9.6?×?10^?10 cm²/s and 7.8?×?10^?9 S/cm for Li _x TaO _y C _z films by co-synthesis with an APPJ.     

A Sensitive Method for Determination Glycolic Acid, Mono- and Di-Chloroacetic Acids in Betaine Media Using Amino-Functionalized SBA-15 as a Sorbent and HPLC Assay

In this paper, amino-modified nanoporous silica (APS-SBA-15) was synthesized as a new solid-phase sorbent for the extraction of glycolic acid, monochloroacetic acid, and dichloroacetic acid in synthetical betaine products. Octadecyl silica cartridge was used to reduce the concentration of matrix betaine. PS-Ag⁺ pre-treatment cartridge was applied to remove high Cl^? concentration. The obtained effluent sample was passed through of the APS-SBA-15 sorbent. The effect of pH, flow rate of sample and eluent, and type and volume of the eluent were investigated and optimized. Chloroacetate and glycolate were eluted with 0.8 mol L^?1 solution of HClO₄ and measured by HPLC with a UV–vis detector. At optimum effective parameters, preconcentration factor of 129 was achieved in this method. The detection limits of mono- and dichloroacetic acid and glycolic acid were 13, 3.7, and 8.6 ng L^?1, respectively.     

Intermolecular complexes of nido-C<Subscript>2</Subscript>B<Subscript>3</Subscript>H<Subscript>7</Subscript> with HF and LiH molecules: the theoretical studies,bonding properties and natural bond orbital (NBO) analysis

The changes in stabilization energy upon the formation of intermolecular hydrogen, dihydrogen and lithium bond complexes between C₂B₃H₇, LiH and HF have been investigated using MP2 method with aug-cc-pVDZ basis set. The interaction of HF with nido-C₂B₃H₇ could occur through the formation of B–H^?δ···^+δH–F, C–H^+δ···F^?δ–H and B–C···H–F classical and non-classical hydrogen bonds. The B–C bonds in backbone of the C₂B₃H₇ as electron donor interact with σ* orbital of HF as electron acceptor. Also interaction of LiH with nido-C₂B₃H₇ resulted in B–C···Li–H and B–H···LiH lithium bonds as well as C–H···H–Li dihydrogen bond complexes. In some of these complexes, LiH interacts with B–C bonds. Results are indicating that more stable complexes belong to interaction of HF and LiH with backbone of the nido-C₂B₃H₇. The AIM and NBO methods were used to analyze the intermolecular interactions; also the electron density at the bond critical point and the charge transfer of obtained complexes were studied.     

Adsorption of Li by a lithium ion-sieve using a buffer system and application for the recovery of Li from a spent lithium-ion battery

A lithium ion-sieve manganese oxide (MO) derived from Li-enriched MO was prepared by the glycolic acid complexation method. The Li adsorption performance in a LiCl–NH₃·H₂O–NH₄Cl buffer solution, simulated a spent lithium-ion battery (LIB) processing solution, and actual spent LIB processing solution were studied. An adsorption capacity of 27.4 mg/g was observed in the LiCl–NH₃·H₂O–NH₄Cl buffer solution (Li concentration of 0.2 mol/L, pH?=?9), and the adsorption behavior conformed to the Langmuir adsorption isotherm equation with a linear correlation coefficient (R²) of 0.9996. An adsorption capacity of 19 mg/g was observed in the simulated buffer spent battery solution (Li concentration of 0.15 mol/L, pH?=?7), and an adsorption capacity of 17.8 mg/g was observed in the actual spent battery solution (Li concentration of 0.15 mol/L, pH?=?7). X-ray diffraction, scanning electron microscope, and infrared spectrum results revealed that the structure and morphology of MO are stable before and after adsorption, and the adsorption of MO in all of the abovementioned buffer systems conforms to the Li⁺–H⁺ ion-exchange reaction mechanism. The lithium ion-sieve MO demonstrates promise for the recovery of lithium from spent LIBs.     

Insights into the Mechanism of Extraction of Uranium (VI) from Nitric Acid Solution into an Ionic Liquid by using Tri‐n‐butyl phosphate

We present new results on the liquid–liquid extraction of uranium (VI) from a nitric acid aqueous phase into a tri‐n‐butyl phosphate/1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (TBP/[C₄mim][Tf₂N]) phase. The individual solubilities of the ionic‐liquid ions in the upper part of the biphasic system are measured over the whole acidic range and as a function of the TBP concentration. New insights into the extraction mechanism are obtained through the in situ characterization of the extracted uranyl complexes by coupling UV/Vis and extended X‐ray absorption fine structure (EXAFS) spectroscopy. We propose a chemical model to explain uranium (VI) extraction that describes the data through a fit of the uranyl distribution ratio D_U. In this model, at low acid concentrations uranium (VI) is extracted as the cationic complex [UO₂(TBP)₂]²⁺, by an exchange with one proton and one C₄mim⁺. At high acid concentrations, the extraction proceeds through a cationic exchange between [UO₂(NO₃)(HNO₃)(TBP)₂]⁺ and one C₄mim⁺. As a consequence of this mechanism, the variation of D_U as a function of TBP concentration depends on the C₄mim⁺ concentration in the aqueous phase. This explains why noninteger values are often derived by analysis of D_U versus [TBP] plots to determine the number of TBP molecules involved in the extraction of uranyl in an ionic‐liquid phase.     

Liquid–Liquid Equilibria for Extraction of Citrus Essential Oil Using Ionic Liquids

The object of this study was to measure the liquid–liquid equilibria (LLE) data of binary mixtures containing ionic liquids and citrus essential oil. We investigated linalool as the citrus essential oil, and 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([C _n MIM]⁺[TFSI]^?) as the ionic liquid. Firstly, the experimental apparatus and procedure for the LLE measurement of mixtures containing ionic liquids were verified by measuring the LLE of the binary mixture 1-hexyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([C₆MIM]⁺[TFSI]^?) + 1-hexanol as a reference test system recommended by Marsh et al. (Pure Appl Chem 81:781–789, 2009). Next, the LLE data for IL + linalool were obtained, and the LLE data of two binary mixtures 1-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([C₄MIM]⁺[TFSI]^?) or [C₆MIM]⁺[TFSI]^? + linalool were determined. The experimental LLE data were satisfactorily represented by the non-random two-liquid model.     

New NASICON type oxyanion high capacity anode, Li2Co2(MoO4)3, for lithium-ion batteries: preliminary studies

We describe in this paper the lithium insertion/extraction behavior of a new NASICON type Li₂Co₂(MoO₄)₃ at a low potential and explored the possibility of considering this new oxyanion material as anode for lithium-ion batteries for the first time. Li₂Co₂(MoO₄)₃ was synthesized by a soft-combustion glycine-nitrate low temperature protocol. Test cells were assembled using composite Li₂Co₂(MoO₄)₃ as the negative electrode material and a thin lithium foil as the positive electrode material separated by a microporous polypropylene (Celgard® membrane) soaked in aprotic organic electrolyte (1 M LiPF₆ in EC/DMC). Electrochemical discharge down to 0.001 V from OCV (～3.5 V) revealed that about 35 Li⁺ could ^possibly be inserted into Li₂Co₂(MoO₄)₃ during the first discharge (reduction) corresponding to a specific capacity amounting to 1,500 mAh g^?1. This is roughly fourfold higher compared to that of frequently used graphite electrodes. However, about 24 Li⁺ could be extracted during the first charge. It is interesting to note that the same amount of Li⁺ could be inserted during the second Li⁺ insertion process (second cycle discharge) giving rise to a second discharge capacity of 1,070 mAh g^?1. It was also observed that a major portion of lithium intake occurs below 1.0 V vs Li/Li⁺, which is typical of anodes being used in lithium-ion batteries.     

Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/rice husk-based maco-/mesoporous carbon bone nanocomposite as superior high-rate anode for lithium ion battery

Rice husks (RHs), a kind of biowastes, are firstly hydrothermally pretreated by HCl aqueous solution to achieve promising macropores, facilitating subsequently impregnating ferric nitrate and urea aqueous solution, the precursor of Fe₃O₄ nanoparticles. A Fe₃O₄/rice husk-based maco-/mesoporous carbon bone nanocomposite is finally prepared by the high-temperature hydrothermal treatment of the precursor-impregnated pretreated RHs at 600 °C followed by NaOH aqueous solution treatment for dissolving silica and producing mesopores. The macro-/mesopores are able to provide rapid lithium ion-transferring channels and accommodate the volumetric changes of Fe₃O₄ nanoparticles during cycling as well. Besides, the macro-/mesoporous carbon bone can offer rapid electron-transferring channels through directly fluxing electrons between Fe₃O₄ nanoparticles and carbon bone. As a result, this nanocomposite delivers a high initial reversible capacity of 918 mAh g^?1 at 0.2 A g^?1 and a reversible capacity of 681 mAh g^?1 remained after 200 cycles at 1.0 A g^?1. The reversible capacities at high current densities of 5.0 and 10.0 A g^?1 still remain at high values of 463 and 221 mAh g^?1, respectively.     

Determination of Estrogens in Water Samples by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with High Performance Liquid Chromatography

Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]) ionic liquid as extraction solvent, five estrogens including estrone (E₁), 17β-estradiol (E₂), estriol (E₃), 17α -ethynylestradiol (EE₂), and diethylstilbestrol (DES) in water samples were determined by dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography with a photodiode array detector and a fluorescence detector (HPLC-DAD-FLD). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C₆MIM][PF₆] dispersed entirely into the sample solution with the help of a disperser solvent (acetone). Parameters including both extraction and disperser solvents and their volumes, extraction and centrifugal time, sample pH, and salt effect were investigated and optimized. Under the optimized conditions, 110–349 fold enrichment factors of analytes were obtained. The calibration curves were linear in the concentration range of 0.2–100 µg L^?1 for E₂, E₃, and EE₂ detected with FLD, and 1–100 µg L^?1 for E₁ and DES detected with DAD. The correlation coefficient of the calibration curve was between 0.9990 and 0.9997. The limits of detection (LOD, S/N = 3) for the five estrogens were in the range of 0.08–0.5 µg L^?1. The relative standard deviations (RSD) for six replication experiments at the concentration of 5.0 µg L^?1 were ≤5.7%. The proposed method was applied to the analysis of three water samples from different sources (river water, waste water, and sea water). The relative recoveries of spiked water samples are satisfied with 89.3–102.4% and 88.7–105.2% at two different concentration levels of 5.0 and 50.0 µg L^?1, respectively.     

Low-temperature thermodynamics of Ln(Me2dtc)3(C12H8N2) (Me2dtc = dimethyldithiocarbamate, Ln = La, Pr, Nd, Sm)

The heat capacities of Ln(Me₂dtc)₃(C₁₂H₈N₂) (Ln = La, Pr, Nd, Sm, Me₂dtc = dimethyldithiocarbamate) have been measured by the adiabatic method within the temperature range 78–404 K. The temperature dependencies of the heat capacities, C _p,m [La(Me₂dtc)₃(C₁₂H₈N₂)] = 542.097 + 229.576 X ? 27.169 X ² + 14.596 X ³ ? 7.135 X ⁴ (J K^?1 mol^?1), C _p,m [Pr(Me₂dtc)₃(C₁₂H₈N₂)] = 500.252 + 314.114 X ? 17.596 X ² ? 0.131 X ³ + 16.627 X ⁴ (J K^?1 mol^?1), C _p,m [Nd(Me₂dtc)₃(C₁₂H₈N₂)] = 543.586 + 213.876 X ? 68.040 X ² + 1.173 X ³ + 2.563 X ⁴ (J K^?1 mol^?1) and C _p,m [Sm(Me₂dtc)₃(C₁₂H₈N₂)] = 528.650 + 216.408 X ? 16.492 X ² + 12.076 X ³ + 4.912 X ⁴ (J K^?1 mol^?1), were derived by the least-squares method from the experimental data. The heat capacities of Ce(Me₂dtc)₃(C₁₂H₈N₂) and Pm(Me₂dtc)₃(C₁₂H₈N₂) at 298.15 K were evaluated to be 617.99 and 610.09 J K^?1 mol^?1, respectively. Furthermore, the thermodynamic functions (entropy, enthalpy and Gibbs free energy) have been calculated using the obtained experimental heat capacity data.