Influence of co-ions in the eluent on the separation factor of lithium isotopes

The influence of co-ions in the eluent on the separation factor () of lithium isotope separation has been studied by ion exchange chromatography. A strongly acid cation exchange resin (Dowex 50W-X8) was used for the separation of lithium isotopes. The co-ions used in eluent were H⁺, K⁺, Ba²⁺, Cu²⁺, Al³⁺ and Cr³⁺ as their chlorides. From the experiments, it was found that⁶Li was enriched in the resin phase and⁷Li in solution phase. At the same distribution coefficient (K_d=30), the separation factor increased linearly with the charge of co-ion (=1.0022 to 1.0039).     

Influence of chelating agents in eluent on the separation factor of lithium isotopes

The influence of chelating agents on the separation factor, , of lithium isotopes separation was studied by ion exchange elution chromatography. Eluents contained the chelating agent having different number of coordination sites. The chelating agents used in eluent were Na-glycine (Na–Gly), 2Na-iminodiacetic acid (2Na-IDA), 3Na-nitrilotriacetic acid (3Na-NTA), and 4Na-ethylenediaminetetraacetic acid (4Na-EDTA). The ion exchanger was Dowex 50W-X8, sulfonic acid type, sodium form. As a result,⁶Li was enriched in resin phase, and⁷Li was in solution phase. The separation factor, , was gradually increased with increasing number of coordination site (=1.0022–1.0038) at the same distribution coefficient and with increasing distribution coefficients (=1.0017–1.0026) at the same concentration of chelating agents.     

The Influence of Electric Parameters on the Dynamics of the Electrokinetic Decontamination of Soils

Elution chromatographic separation of lithium isotopes was carried out with aminobenzo-15-crown-5 bonded merrifield resin. This resin have a capacity of 0.24 meq/g dry resin. By column chromatography using 1.0M NH₄Cl solution as an eluent, a single separation factor 1.026 was obtained from the elution curve and isotope ratios according to the Glucckauf theory. The heavier isotope, ⁷Li was concentrated in the resin phase, while the lighter isotope, ⁶Li enriched in the solution phase.     

Syntheses and separating properties of triazacrown and AM18C6 bonded Merrifield peptide resins

Separation of lithium and magnesium isotopes by cation exchange elution chromatography was carried out with a synthesized 1,13,16-trioxa-4,7,10-triazacyclooctadecane (N₃O₃)-4,7,10-trimerrifield peptide resin and with a 2^′-aminomethyl-18-crown-6 (AM18C6) bonded Merrifield peptide resin. The resins have a capacity of 0.1 and 2.3 meq/g dry resin. A single stage separation factor of lithium isotopes, 1.018 was obtained by the Glueckauf theory from the elution curve and isotopic assays. The heavier isotope, ⁷Li was concentrated in the resin phase, while the lighter isotope, ⁶Li concentrated in the solution phase. On the other hand, the heavier isotopes of magnesium were concentrated in the solution phase, while the lighter isotopes were concentrated in the resin phase. The separation factors of ²⁴Mg-²⁵Mg, ²⁴Mg-²⁶Mg, and ²⁵Mg-²⁶Mg isotope pair fractionations were 1.012, 1.022, and 1.012, respectively.     

Separation of lithium isotopes by NTOE-bonded Merrifield peptide resin

A study of the elution chromatographic separation of lithium isotopes was carried out with NTOE-bonded Merrifield peptide resin. This resin had a capacity of 0.29 meq/g dry resin. Upon column chromatography [0.2 cm(I.D)×32 cm (height)] using 1.0M NH₄Cl solution as an eluent, a single separation factor of 1.026 was obtained by the Glueckauf theory. The heavier isotope, ⁷Li was concentrated in the resin phase, while the lighter isotope, ⁶Li was enriched in the solution phase.     

Enrichment of lithium isotopes by a triazacrown trimerrifield peptide resin

A study on the elution chromatographic separation of lithium isotopes was carried out with a triazacrown trimerrifield peptide resin. The capacity of the triazacrown trimerrifield peptide resin has a value of 0.08 meq/g. Upon column chromatography [0.2 cm (I.D)×35 cm (height)] using 4.0M NH₄Cl solution as an eluent, the single stage separation factor of 1.028 was obtained by the Glueckauf theory. The heavier isotope, ⁷Li, was concentrated in the resin phase, while the lighter isotope, ⁶Li, was enriched in the solution phase.     

Separation of lithium isotopes by elution chromatography with an AB18C6 bonded Merrifield peptide resin

Cation exchange chromatographic separation of lithium isotopes was carried out with an 4'-aminobenzo-18-crown-6(AB18C6) bonded Merrifield peptide resin. This resin has a capacity of 2.25 meq/g dry resin. Upon column elution chromatography, a single stage separation factor of 1.0095, was obtained by the Glueckauf theory from the elution curve and isotopic assays. The heavier isotope, ⁷Li, was concentrated in the resin phase, while the lighter one, ⁶Li, concentrated in the solution phase.     

A green strategy for lithium isotopes separation by using mesoporous silica materials doped with ionic liquids and benzo-15-crown-5

Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C₈mim⁺PF₆ ^?, C₈mim⁺BF₄ ^? or C₈mim⁺NTf ₂ ^? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N₂ gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope ⁷Li was concentrated in the solution phase while the lighter isotope ⁶Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of ⁶Li–⁷Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li_0.5)₂(B15)₂(H₂O)]⁺ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L^?1 HCl and reused in the consecutive removal of lithium ion in five cycles.     

Separation of lithium isotopes with the N3O2 trimerrifield peptide resin

A study on the separation of lithium isotopes was carried out with 1,13-dioxa-4,7,10-triazacyclopentadecane-4,7,10-trimerrifield peptide resin [N₃O₂3M]. The resin having N₃O₂ as an anchor group has a capacity of 0.2 meq/g dry resin. Upon column chromatography [0.1 cm (I.D)×30 cm (height)] using 1.0M NH₄Cl solution as an eluent, a single separation factor of 1.00104 was obtained from the elution curve and isotope ratios based on theGlueckauf theory. The heavier isotope,⁷Li concentrated in the resin phase, while the lighter isotope,⁶Li enriched in the solution phase.     

Separation of lithium isotopes by NDOE bonded Merrifield peptide resin

The novel NDOE (1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane) ion exchange resin was prepared. The ion exchange capacity of NDOE azacrown ion exchanger was 0.2 meq/g dry resin. A study on the separation of lithium isotopes was carried out with NDOE novel azacrown ion exchange resin. The lighter isotope,⁶Li concentrated in the solution phase, while the heavier isotope,⁷Li is enriched in the resin phase. By column chromatography (0.1 cm I.D.×32 cm height) using 2.0M NH₄Cl as an eluent, a separation factor,a=1.0201 was obtained.     

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.     

Separation of lithium isotopes by N4S2 azacrown ion exchanger

The novel N₄S₂ azacrown ion exchange resin was prepared. The ion exchange capacity of N₄S₂ ion exchanger was 0.34 meq/g dry resin. A study on the separation of lithium isotopes was carried out with N₄S₂ azacrown ion exchange resin. The lighter isotope,⁶Li is concentrated in the resin phase, while the heavier isotope,⁷Li is enriched in the solution phase. With column chromatography [0.1 cm (I.D.)×32 cm (height)] using 2.0M NH₄Cl as an eluent, separation factor, a=1.034 was obtained.     

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.     

Simultaneous production of89Zr and90,91m92mNb in α-particle activated yttrium and their subsequent separation by TOA

A study on the separation of lithium isotopes was carried out with an ion exchange resin having 1,7,13-trioxa-4,10,16-triazacyclooctadecane (N₃O₃) as an anchor group. The lighter isotope,⁶Li concentrated in the resin phase, while the heavier isotope,⁷Li is enriched in the fluid phase. Upon column chromatography [0.6 cm (I. D.)×20 cm (height)] using 1.0M ammonium chloride solution as an eluent, single separation factor, , 1.068 (⁶Li/⁷Li)_resin/(⁶Li/⁷Li)_solution was obtained by theGlueckauf method from the elution curve and isotope ratios.     

Separation of lithium isotope by azacrown tetramerrifield peptide resin

A study on the separation of lithium isotope was carried out with N₄O azacrown ion exchange resin. The lighter⁶Li isotope concentrated in the solution phase, while the heavier⁷Li isotope is enriched in the resin phase. Upon column chromatography (0.3 cm I.D.×15.5cm height) using 0.5M NH₄Cl as an eluent, single separation factor, α=1.00127 was obtained.     

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.     

Photoefficiency of gamma-radiation recording and limits of detection for individual elements in activation analysis using Ge(Li) semiconductor detectors

The photoefficiency and source utilization coefficients for 3.5, 28 and 45 cm³ Ge(Li) detectors were determined. Values of the source utilization coefficient were obtained as a function of the measurement geometry. Limits of detection were determined for 30 elements with long-lived isotopes and 38 elements with short-lived isotopes.     

Separation and concentration of cobalt from ammoniacal solutions containing cobalt and nickel by emulsion liquid membranes using 5,7-dibromo-8-hydroxyquinoline (DBHQ)

The separation and concentration of cobalt from ammoniacal solutions containing nickel and cobalt by an emulsion liquid membranes (ELMs) using 5,7-dibromo-8-hydroxyquinoline as extractant has been presented. Membrane solution consists of a diluent (kerosene), a surfactant (Span 80), a modifier (tributylphosphate), and an extractant (DBHQ). Very dilute sulphuric solution containing EDTA as complexing agent, buffered at pH 5.0, has been used as a stripping solution. pH of ammoniacal feed solution containing cobalt and nickel was adjusted to 9.0 with hydrochloric acid. The important variables governing the permeation of cobalt have been studied. These variables are membrane composition, pH of the feed solution, cobalt and nickel concentrations of the feed solution, mixing speed, surfactant concentration, extractant concentration, EDTA concentration and pH of the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively extract 99.0% of cobalt from ammoniacal feed solution containing Co²⁺ and Ni²⁺ ions. The separation factors of cobalt with respect to nickel, based on initial feed concentration, have experimentally found to be of as high as 247.5 for about equimolar Co–Ni feed solutions.     

Extractive separation of lithium isotopes by 4-tert-butylbenzo-15-crown-5

Based on the principle of an empirical equation, an extractive process has been developed for separating isotopes of lithium. A 2.5M aqueous solution of lithium perchlorate was contacted with twice its volume of 1.0M solution of 4-tert-butylbenzo-15-crown-5 in nitrobenzene at 25 °C to obtain a lithium isotope separation factor of 1.036 and a percent extaction of lithium reaching 45%. With 13 stages of extraction, the concentration of lithium perchlorate in the raffinate was reduced from 2.5M to 2.5×10^–4M to meet the needs of recycling cascade. With 4 stages of scrubbing by use of identical volumes of water at 60 °C, the overall recovery of lithium was found to be >99%.     

Chromatographic Zinc Isotope Separation by Chelating Exchange Resin

Zinc isotope separations were studied by displacement chromatography using the chelating properties of malate, citrate and lactate exchange resin and EDTA as ligands. After each chromatographic operation, the heavier zinc isotopes were found to preferentially fractionated into the carboxylate complex solution phase. The separation coefficients (ε) for zinc isotope separation had the largest value and were obtained for the isotopic pairs ⁶⁸Zn/⁶⁴Zn (7.16 × 10^?4) and ⁶⁶Zn/⁶⁴Zn (3.08 × 10^?4), respectively, at 298 ± 1 K. The separation coefficient per unit mass differences (ε/ΔM) for the isotopic pair of ⁶⁸Zn/⁶⁴Zn was found to range around 1.55 × 10^?4.