Lithium Ions In Aqueous Solution Research Articles

Tri(ethylene glycol) modified HYC‐100 resin for lithium ion recovery from aqueous solution

AbstractPolymeric resin has shown great application in recovery the lithium ion from aqueous solution due to their structure's tunability and reusability. However, the conventional resins such as commercial HYC‐100 is suffering by its low lithium adsorption capacity and slow inclusion rate. Herein, a series of HYC‐100 modified resins (MRs) using oligo(ethylene glycol) as crosslinker were synthesized and their adsorption capacities for lithium ion in aqueous solution (pH 9.1, ionic concentration 500 mg/L, 25°C) were determined by adding 1 g resin to 500 mL lithium chloride aqueous solution. The new formed cyclic structure from oligo(ethylene glycol) provides lithium ion binding sites which play an important role for lithium ion adsorption. The tri(ethylene glycol) modified resin (3EGMR) showed the highest capacity to be 18 mg/g, which was three times more than that of HYC‐100 (5 mg/g). Therefore, Scale‐up experiment was conducted by using 20 L reactor and the adsorption capacity is satisfactory. This work might pave a new avenue to develop new polymeric resin to enhance the lithium ion adsorption performance.

Nuclear magnetic resonance spin-lattice relaxation of lithium ions in aqueous solution by NMR and molecular dynamics.

We study the aqueous solvation dynamics of lithium ions using nuclear magnetic resonance spectroscopy, molecular dynamics, and viscosity measurements. Several relaxation mechanisms are examined to explain the strong increases of spin-lattice relaxation toward high concentrations. The use of both 6Li and 7Li isotopes is helpful to identify the quadrupolar contribution to the relaxation rate. In particular, it is found that the quadrupolar interaction constitutes the strongest contribution above a concentration of ∼10 molal. The next-strongest contribution arises from interactions that scale with the square of the gyromagnetic ratio (mostly the dipolar interaction), and the experimental relaxation rates appear to be fully accounted for when these mechanisms are combined over the concentration range up to the saturation concentration. The study of solvation dynamics, particularly at high concentrations, could be of relevance for electrolyte dynamics in aqueous Li-ion rechargeable batteries.

Lithium isotope separation by electromigration

Lithium-6 and lithium-7 with high abundance can be used in fusion (6Li > 30%) and fission (7Li > 99.9%) respectively. Lithium isotope separation with nature abundance always inspires people's interest. In this work, lithium isotope separation by electromigration from lithium-loaded organic phase to aqueous solution was investigated. It was found that immigrant lithium ions in aqueous solution enriched lithium-7 at 1.5 V and enriched lithium-6 at 20 V. After electromigration, the lithium isotope value in aqueous solutions could reach −21.5. The results confirmed the isotopic separation effect of lithium ions electromigration which attributed to dissociating difference of lithium isotopic ions-crown ethers complex.

Effect of chemical treatments on lithium recovery process of activated carbons

In this work, surface characteristics of chemically treated activated carbons (ACs) were studied for lithium ion in aqueous solution. From the results, it was found that the chemical treatments introduced functional groups onto the ACs surfaces. The amount of lithium ion recovery was enhanced by basic treatments. Also, we characterized lithium ion adsorption-desorption efficiency. The lithium adsorption-desorption efficiency exhibited good stability after five adsorption–desorption cycles. Consequently, it could be concluded that lithium ion recovery behaviors are greatly influenced by the basic characteristics of AC surfaces, resulting in enhanced electron acceptor-donor interaction at interfaces.

Study of lithium ion intercalation/de-intercalation into LiNi1/3Mn1/3Co1/3O2 in aqueous solution using electrochemical impedance spectroscopy

The mechanism of lithium ion intercalation/de-intercalation into LiNi1/3Mn1/3Co1/3O2 cathode material prepared by reactions under autogenic pressure at elevated temperatures method is investigated both in aqueous and non-aqueous electrolytes using electrochemical impedance spectroscopy (EIS) technique. In accordance with the results obtained an equivalent circuit is used to fit the impedance spectra. The kinetic parameters of intercalation/de-intercalation processes are evaluated with the help of the same equivalent circuit. The dependence of charge transfer resistance (R ct), exchange current (I 0), double layer capacitance (C dl), Warburg resistance (Z w), and chemical diffusion coefficient (D Li+) on potential during intercalation/de-intercalation is studied. The behavior of EIS spectra and its potential dependence is studied to get the kinetics of the mechanism of intercalation/de-intercalation processes, which cannot be obtained from the usual electrochemical studies like cyclic voltammetry. The results indicate that intercalation and de-intercalation of lithium ions in aqueous solution follows almost similar mechanism in non-aqueous system. D Li+ values are in the range of 10−8 to 10−14 cm2 s−1 in aqueous 5 M LiNO3 and that in non-aqueous 1 M LiAsF6/EC+DMC electrolyte is in the order of 10−12 cm2 s−1 during the intercalation/de-intercalation processes. A typical cell LiTi2 (PO4)3/5 M LiNO3/LiNi1/3Mn1/3Co1/3O2 is constructed and the cycling stability is compared to that with an organic electrolyte.

Theoretical Estimation of Lithium Isotopic Reduced Partition Function Ratio for Lithium Ions in Aqueous Solution

The reduced partition function ratio for lithium ions in an aqueous solution is derived from the extrapolation of the values of the reduced partition function ratio ( ) of hydrated lithium ion clusters [Li(H2O)n]+ up to n = 6. In [Li(H2O)n]+ clusters, the values can be calculated from the normal vibration frequencies according to Bigeleisen and Mayer's theory. To obtain the values of , the normal vibration frequency calculations were carried out for optimized structures of [Li(H2O)n]+ (n = 1−6) using the RHF/6-31+G(d), RHF/6-31++G(d,p), RHF/6-311+G(d) and MP2/6-31+G(d) methods by means of the ab initio molecular orbital method. All of those structures having high symmetry were confirmed to have real harmonic frequencies at the RHF/6-31+G(d) and RHF/6-31++G(d,p) levels. For the two RHF methods, the value of increases to about 1.07 with an increase of the hydration number n, and reaches maximum at n = 4. In the most stable isomers of [Li(H2O)n]+ clusters for n = 5 and 6, respectively, the first hydration shell is saturated with the four water molecules, and the size dependence of the values converges for n ≥ 4. The converged value 1.07 can, therefore, be regarded as the reduced partition function ratio for lithium ions in aqueous solution, and gives the upper limit of the isotopic separation factor in an aqueous solution−exchanger system.

Spectrophotometric determination of lithium ion using a water-soluble octabromoporphyrin in aqueous solution

A water-soluble porphyrin, (2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin; H 2obtpps 4−) was synthesized and developed for the determination of lithium ion in aqueous solution. The octabromo groups lower the basicity of the porphyrin by their electron-withdrawing effect, and enable the porphyrin to react with the lithium ion in alkaline solution to form the lithium complex along with a shift of absorption maximum: λ max/nm (log ε/mol −1 dm 3 cm −1) of the lithium porphyrin are 490.5 nm (5.31) and 734 nm (4.36). Sodium and potassium ions did not react with the porphyrin. The equilibrium constant for the reaction Li ++Hobtpps 5−⇌[Li(obtpps)] 5−+H + was found to be 10 −8.80 and the conditional formation constant of the [Li(obtpps)] 5− at pH 13 is 10 4.21. The above results were applied to the determination of lithium ion in aqueous solution. The interference from transition and heavy metal ions was masked by using N, N′-1,2-ethanediylbis[ N(carboxylmethy)glycinato]magnesium(II) ([Mg(edta)] 2−) solution. Absorbance at 490 nm was measured against a blank solution. A calibration graph was linear over the range of 0.007–0.7 μg cm −3 (1×10 −6–1×10 −4 mol dm −3) of lithium(I) with a correlation factor of 0.967. Lithium ion less than ppm level was determined spectrophtometrically in aqueous solution. The proposed method was applied to the determination of lithium in human serum and sea water samples.

Trace Analysis of Lithium with a Water-Soluble Porphyrin

A water-soluble porphyrin (2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin ; H2obtpps4-; H2P4-) was synthesized and developed for the determination and separation of lithium ion in aqueous solution. The octabromo groups lower the basicity of the porphyrin by their electron-withdrawing effect, and enable the porphyrin to react with lithium ion in alkaline aqueous solution to form the lithium complex along with a shift of absorption maxima; λmax (log ∈/mol-1 dm3 cm-1) of the lithium porphyrin are 490.5 nm (5.31) and 734 nm (4.36). Sodium and potassium ions did not react with the porphyrin. The equilibrium constant for the reaction Li+ + HP5- ⇌ [LiP]5- + H+ was found to be 10-8.79 and the conditional formation constant of the [LiP]5- at pH 13 is 104.21. The [LiP]5- can be extracted into chloroform as an ion-pair complex with tetrabutylammonium ion (X+) and the extracted X5LiP dissociates to X4LiP- and X+ in chloroform. The extraction constant for the reaction of [LiP5-]a + 5[X+]a ⇌ [X4LiP-]o + [X-]o was found to be (8.4 ± 0.7) × 1012 mol-4 dm12, where subscripts of a and o denote chemical species in aqueous and organic phases, respectively. The above results were developed for the determination of lithium in serum, sea water and hot spring water samples at a range of 0.07–0.7 mg dm-3 (1 × 10-5 - 1 × 10-4 mol dm-3). The interference of heavy metal ions was masked by N,N'-1,2-ethanediylbis[N-(carboxylmethyl)glycinato]magnesium(II) ([Mg(edta)]2- or H4edta if sample contain magnesium(II) ion.

Lithium(I) Porphyrin Complex for the Spectrophotometric Determination of Lithium Ion in Aqueous Solution.

A water-soluble octabromoporphyrin has been synthesized and developed for the determination of lithium ion in aqueous solution. The porphyrin reacts with lithium ion in alkaline solution to form the lithium complex along with a shift of absorption maximum to shorter wave length. But sodium and potassium ions do not react with the porphyrin. The equilibrium constant of the Li(I) porphyrin complex was determined and applied to the determination of lithium(I) in natural water. Interference of metal ions was removed by ligand buffer of Mg-EDTA complex.

Synthesis of a small azacage which can selectively encapsulate a lithium ion in aqueous solution

Synthesis of 4,10-dimethyl-1,4,7,10,15-penta-azabicyclo[5.5.5]heptadecane (L) which encapsulates a lithium ion in aqueous solution and the crystal structure of [LiL][ClO4] are reported.