Hydrothermal extraction of potassium,sodium, rubidium and cesium from rocks by lithium hydroxide and determination at very low natural levels

The selective extraction of Na, K, Rb and Cs from rocks is described. The method is particularly designed for low levels of rubidium and cesium in basic and ultrabasic rocks. The rocks are decomposed with lithium hydroxide solution at 180°C. Only part of the aluminium and chromium accompany the alkali metals into solution; all other rock constitutents are left behind as insoluble lithium silicate, hydroxides of divalent metals, etc. Concentration of rubidium and cesium too low to be determined directly by flame emission spectrometry are pre-concentrated up to 25-fold by liquid-liquid extraction. Quantitative recovery (>99.5%) of the two metals is achieved by coprecipitation with potassium tetraphenylboron within the organic phase (di-isobutyl ketone) for subsequent back-extraction and dissolution in an acidic aqueous phase. Detection limits are 1 mg kg^?1 Na or K, 0.1 mg kg^?1 Rb and 0.05 mg kg^?1 Cs in the rock for the direct determination and 0.003 mg kg^?1 Rb and 0.001 mg kg^?1 Cs after preconcentration. Methods are described for the purification of lithium hydroxide and the potassium nitrate used as carrier. Results are presented for the Na₂ O, K₂O, Rb and Cs contents and the K/Rb values for 23 geochemical references samples (basic and ultrabasic rocks, and iron formation samples).     

Separation of cesium-137 from uranium fission products via a Neoflon® column supporting tetraphenylboron

Cesium is a member of the Group I alkali metals, very reactive earth metals that react vigorously with both air and water. The chemistry of cesium is much like the chemistry of neighboring elements on the periodic table, potassium and rubidium. This close relation creates many problems in plant-life exposed to cesium because it is so easily confused for potassium, an essential nutrient to plants. Radioactive ¹³⁴Cs and ¹³⁷Cs are also chemically akin to potassium and stable cesium. Uptake of these radioactive isotopes from groundwater by plant-life destroys the plant-life and can potentially expose humans to the radioactive affects of ¹³⁴Cs and ¹³⁷Cs. Much experimental work has been focused on the separation of ¹³⁷Cs from uranium fission products. In previous experimental work performed a column consisting of Kel-F supporting tetraphenylboron (TPB) was utilized to separate ¹³⁷Cs from uranium fission products. It is of interest at this time to attempt the separation of ¹³⁴Cs from 0.01M EDTA using the same method and Neoflon in the place of Kel-F as the inert support. The results of this experiment give a separation efficiency of 88% and show a linear relationship between the column bed length and the separation efficiency obtained.     

Rapid determination of 137Cs in environmental samples--purification of 137Cs by ammonium molybdophosphate column separation]

A rapid method for the determination of 137Cs in environmental samples was proposed. The principal technic employed in this study is based on column separation of 137Cs using ammonium molybdophosphate mixed with glass fiber to eliminate contribution of natural radionuclides such as 40K and 87Rb. The separation of cesium from potassium and rubidium was performed by the elution with 0.5m ammonium nitrate solution. The time required for separation of cesium was five hours as compared with the conventional cation exchange separation which required thirteen hours. The chemical yield of cesium carrier was normally more than 90 percent. The results obtained were compared with that by the conventional methods using Bio-Rex cation exchange separation and the good agreement between the two methods was obtained.     

Raman spectra of isotopic bisulfite and disulfite ions in alkali salts and aqueous solution

The Raman spectra of solid lithium, sodium, potassium, cesium, rubidium, and ammonium disulfite and of rubidium and cesium bisulfite were recorded and compared with the spectrum of an aqueous solution saturated with 1.2m K₂S₂O₅. Deuterium, ³⁴S₈, and ¹⁸O₂ were used to label cesium bisulfite, CsHSO₃, cesium disulfite, Cs₂S₂O₅, and potassium disulfite. All six fundamentals of the bisulfite ion were observed and assigned. Eleven of the fifteen expected fundamentals of the disulfite ion were observed and correlated to older experimental data, as well as recent calculations. Isotope shifts confirm assignments in the SO stretching region. In the low frequency region, assignment is less conclusive and two frequencies have been tentatively reassigned.     

Partial molar volumes of monovalent ions in ethanolamine and water + ethanolamine mixtures at 25°C

Precise densities for sodium of chloride, bromide and iodide and potassium iodide in ethanolamine and water+ethanolamine mixtures (15, 30, 50, 60, 70, 80 and 90 mass% ethanolamine) up to a maximum salt molality of 0.15 mol-kg⁻¹ are reported from measurements at 25°C using a vibrating tube densimeter. The electrolyte apparent molar volumes were calculated and extrapolated to infinite dilution using the Masson equation to yield the limiting electrolyte partial molar volumes. The limiting ionic partial molar volumes V _ion ^o were estimated using Mukerjee's method. A correspondence principle proposed earlier for predicting ionic entropies could be used for the estimation of V _ion ^o for rubidium and cesium salts. The estimates of the contributions from geometric and the electrostrictive effects to V _ion ^o are also reported. The variations in these contributions with the change in solvent composition are discussed in terms of the changes in the solvent structure.     

A study of the hydration of the alkali metal ions in aqueous solution

The hydration of the alkali metal ions in aqueous solution has been studied by large angle X-ray scattering (LAXS) and double difference infrared spectroscopy (DDIR). The structures of the dimethyl sulfoxide solvated alkali metal ions in solution have been determined to support the studies in aqueous solution. The results of the LAXS and DDIR measurements show that the sodium, potassium, rubidium and cesium ions all are weakly hydrated with only a single shell of water molecules. The smaller lithium ion is more strongly hydrated, most probably with a second hydration shell present. The influence of the rubidium and cesium ions on the water structure was found to be very weak, and it was not possible to quantify this effect in a reliable way due to insufficient separation of the O-D stretching bands of partially deuterated water bound to these metal ions and the O-D stretching bands of the bulk water. Aqueous solutions of sodium, potassium and cesium iodide and cesium and lithium hydroxide have been studied by LAXS and M-O bond distances have been determined fairly accurately except for lithium. However, the number of water molecules binding to the alkali metal ions is very difficult to determine from the LAXS measurements as the number of distances and the temperature factor are strongly correlated. A thorough analysis of M-O bond distances in solid alkali metal compounds with ligands binding through oxygen has been made from available structure databases. There is relatively strong correlation between M-O bond distances and coordination numbers also for the alkali metal ions even though the M-O interactions are weak and the number of complexes of potassium, rubidium and cesium with well-defined coordination geometry is very small. The mean M-O bond distance in the hydrated sodium, potassium, rubidium and cesium ions in aqueous solution have been determined to be 2.43(2), 2.81(1), 2.98(1) and 3.07(1) ?, which corresponds to six-, seven-, eight- and eight-coordination. These coordination numbers are supported by the linear relationship of the hydration enthalpies and the M-O bond distances. This correlation indicates that the hydrated lithium ion is four-coordinate in aqueous solution. New ionic radii are proposed for four- and six-coordinate lithium(I), 0.60 and 0.79 ?, respectively, as well as for five- and six-coordinate sodium(I), 1.02 and 1.07 ?, respectively. The ionic radii for six- and seven-coordinate K(+), 1.38 and 1.46 ?, respectively, and eight-coordinate Rb(+) and Cs(+), 1.64 and 1.73 ?, respectively, are confirmed from previous studies. The M-O bond distances in dimethyl sulfoxide solvated sodium, potassium, rubidium and cesium ions in solution are very similar to those observed in aqueous solution.     

Highly conducting solid electrolytes based on poly (ethylene oxide-co-propylene oxide)

The conducting properties of solid electrolytes comprising random poly(ethylene oxide-co-propylene oxide) (of 84 : 16 monomer units mole ratio) and lithium, sodium, potassium, cesium, and rubidium salts have been studied. The systems containing some lithium or sodium salts achieved conductivity levels as high as 10^?5–10^?4 S/cm at ambient temperature and greater than 10^?3 S/cm at 100°C. However, the systems with rubidium and cesium salts exhibit conductivities a few orders of magnitude smaller. DSC studies show that the electrolytes studied are characterized by a high content of an amorphous phase (95–100%). It is suggested that the copolymer exhibits lower complexing abilities than that of poly(ethylene oxide), which results in a higher flexibility of electrolytes containing small cations and poor dissociation of the salts having large cations. © 1995 John Wiley & Sons, Inc.     

Determination of traces of rubidium in high purity cesium chloride by electrothermal atomic absorption spectrometry (ETAAS) using boric acid as a modifier

The use of boric acid as a modifier for the determination of trace amount of rubidium in high purity cesium chloride matrix by electrothermal atomic absorption is described. It was found that the negative influence of the chloride matrix could not be eliminated using stabilized temperature platform (STPF) alone. Due to the high dissociation energy (D₀ = 427 kJ mol⁻¹) of rubidium chloride, it was difficult to dissociate in the gas phase and hence is lost. Elimination of interferences was achieved by the addition of boric acid as a chemical modifier. Diluted cesium chloride samples (5%, m/v) were analyzed applying the standard addition method. The characteristic mass of 24 pg was obtained. The detection limit of the proposed method is around 26 ng g⁻¹. The developed method was applied to the determination of traces of rubidium in high purity cesium chloride samples. The data obtained by this method were in good agreement with those obtained by other independent method like FAAS.     

Development of reliable analytical method for extraction and separation of thorium(IV) by Cyanex 272 in kerosene

A simple and selective spectrophotometric method has been developed for the extraction and separation of thorium(IV) from sodium salicylate media using Cyanex 272 in kerosene. Thorium(IV) was quantitatively extracted by 5 × 10⁻⁴ M Cyanex 272 in kerosene from 1 × 10⁻⁵M sodium salicylate medium. The extracted thorium(IV) was stripped out quantitatively from the organic phase with 4.0 M hydrochloric acid and determined spectrophotometrically with arsenazo(III) at 620 nm. The effect of concentrations of sodium salicylate, extractant, diluents, metal ion and strippants has been studied. Separation of thorium(IV) from other elements was achieved from binary as well as multicomponent mixtures such as uranium(VI), strontium(II), rubidium(I), cesium(I), potassium(I), Sodium(I), lithium(I), lead(II), barium(II), beryllium(II) etc. Using this method separation and determination of thorium(IV) in geological and real samples has been carried out. The method is simple, rapid and selective with good reproducibility (approximately ±2%).     

Thermogravimetric investigation of the alkali metal diliturates

Thermolysis curves for lithium, sodium and cesium diliturates have been obtained. Lithium and sodium diliturates form monohydrates from aqueous solutions while potassium, rubidium, and cesium, diliturates are anhydrous.The cesium and rubidium diliturates form rapidly, are quite dense, and easily handled. Both diliturates are thermally stable to about 300°. Methods for the thermogravimetric determination of rubidium and, cesium have been developed and found to be quite accurate.     

Viscosity of cesium halides,rubidium nitrate,and rubidium lodide in diethyleneglycol and aqueous diethyleneglycol at 25°C

The viscosity of cesium chloride, bromide, and iodide, rubidium nitrate and rubidium iodide in diethyleneglycol, and aqueous diethyleneglycol (20% by weight) at 25°C and at concentrations varying from 0.01 to 0.1M are reported. The results are interpreted in terms of the structure-making/structure-breaking capacity of the electrolyte by estimating theB coefficient of the Jones-Dole equation.     

t-BAMBP萃取法分离提取高钾卤水中铷

为解决盐湖卤水中的铷与大量的性质极为相近的碱金属元素钾、钠、锂、铯共存给分离带来的困难,以t-BAMBP为萃取剂,萃取分离了高钾卤水中铷钾,考察了稀释剂种类、萃取剂浓度、碱度、相比、时间等相关因素对分离的影响。结果表明,选定二甲苯体系,1 mol/Lt-BAMBP,碱度1 mol/L NaOH,相比3/1,萃取时间2 min等条件下获得纯度达99.8%RbCl。铷萃取率97.0%,反萃取率98.4%,总回收率为95.5%。     

Separation of alkali metals by extraction chromatography with dipicrylamine and nitrobenzene

An extraction chromatographic method to separate rubidium and cesium using a nitrobenzene solution of ammonium dipicrylaminate has been developed. The procedure is used in connection with a concentration-dependent radioisotope distribution method for determining traces of cesium in rubidium salts. A frontal chromatographic enrichment method to eliminate excess sodium, lithium and calcium salts has been worked out. The results are compared with the conclusions drawn from the extraction mechanism and with other separation procedures. Part VIII of the series “The method of concentration-dependent distribution in the quantitative use of radioisotopes”; for Part VII, seeChem. Listy, 61 (1967) 440.     

Synthesis and Ion Mobility in Glasses of ZrF<Subscript>4</Subscript>–BiF<Subscript>3</Subscript>–Rb(Cs)F Fluoride Systems

A new procedure has been suggested for the synthesis of bismuth fluorozirconate glasses in the ZrF₄–BiF₃–MF systems (M = Rb, Cs), which is based on the use of the relatively moisture-resistant Rb₂ZrF₆ and Cs₂ZrF₆ fluorides rather than extremely hygroscopic rubidium and cesium fluorides. The types of ion motions, trends in ion mobility dynamics, and factors determining this dynamics as a function of the glass composition have been elucidated. A rather high ionic conductivity of glasses above 470 K, σ ≥ 10^–4 S/cm, makes them promising candidates for use in design of functional materials.     

FIA Potentiometric and Solvent Extraction Studies of Alkali Metal and Alkaline Earth Cation Complexation by bis(Tert-butylbenzo)-21-crown-7

Abstract

A flow injection analysis study of the potentiometric selectivity of bis[4(5)-tert-butylbenzo]-21-crown-7 (D(tBB)21C7) for cesium over the other alkali metal cations and three alkaline earth cations has been conducted. A PVC matrix membrane containing D(tBB)21C7 as an ionophore was coated on the tip of a silver wire incorporated in a flow cell. No selectivity for cesium over rubidium and only low selectivity over potassium were noted. However, very high selectivities for cesium over sodium, lithium, strontium, calcium, and magnesium were observed. Selectivity of D(tBB)21C7 in the solvent extraction of alkali metal cations was determined by the picrate extraction method. The percent extraction into deuteriochloroform decreased in the order cesium, rubidium > potassium » sodium » lithium. Thus good agreement was observed between the responses of D(tBB)21C7 towards alkali metal cations in polymeric membrane electrodes and in solvent extraction.     

GC–MS Method Development for the Analyses of Thiophenes from Solvent Extracts of Tagetes patula L

A method for isotachophoretic determination of potassium and ammonium cations in fertilizers and silage was developed. A capillary of 0.4 mm i.d. and 100 mm effective length made of fluorinated ethylene–propylene copolymer was filled with an electrolyte system consisting of 10 mmol L⁻¹ RbOH + 0.1% (w/v) hydroxyethylcellulose, adjusted to pH 9.0 with l-histidine (leading electrolyte) and 10 mmol L⁻¹ lithium citrate (terminating electrolyte). Using contactless conductivity detection, the calibration curves in the tested concentration range up to 0.5 mmol L⁻¹ were linear for both cations. The concentration detection limits for potassium and ammonium were 2.9 and 2.7 μmol L⁻¹, respectively. RSD values of step lengths (n = 6) were 1.3% for potassium and 1.5% for ammonium. The separation time was about 20 min. Similar results were obtained with cesium cation used as the leading ion, however, in the system with rubidium better resolution of other cations present in tested matrices was reached. The elaborated method is simple to perform, sufficiently sensitive and accurate and can be recommended as an alternative procedure to the methods used so far for the determination of potassium and ammonium.

     

Phase equilibria and critical phenomena in the rubidium nitrate-water-acetonitrile system

Phase equilibria and critical phenomena were studied from -5 to 120°C in the rubidium nitrate-water-acetonitrile system, in which the liquid binary subsystem is characterized by liquid-liquid phase separation with an upper critical solution point (UCSP), using a visual polythermal method. We found that rubidium nitrate has a salting out effect on water-acetonitrile solutions and causes them to demix at any temperature in the specified range. Acetonitrile distribution coefficients between aqueous and organic monotectic phases were calculated for various temperatures. The minimum value was observed for 20.0°C. Six isothermal phase diagrams of the system were plotted to verify a fragment of the global scheme of the topological transformation of phase diagrams for salt-binary solvent ternary systems with salting out. The salting out effects of potassium, rubidium, and cesium nitrates on water-acetonitrile mixtures were comparatively analyzed.     

Ion exchange separation of different oxidation states of sulphur formed by35Cl(n,p)35S reaction in alkali halides

Cesium and potassium were determined in muscle-tissues of squid, dover sole, albacore, and bocaccio by NAA. Potassium was measured instrumentally, while cesium was radio-chemically separated. For the separation of cesium, hydrated antimony pentoxide (HAP) was used to retain²⁴Na, and ammonium molybdophosphate (AMP) was used to absorb quantitatively the radiocesium,^134mCs. The cesium and potassium contents were based on measuring the short-lived radionuclide of cesium, 2.90 h-^134mCs, and 12.4 h-⁴²K. The mean concentrations of cesium found, based on 3–4 replicate measurements for each fish, were: 4.18±0.32 ng/g squid, 11.51±0.30 ng/g dover sole, 43.64±1.03 ng/g albacore, and 56.85±3.61 ng/g bocaccio. The mean concentrations of potassium found were: 1.28±0.10 mg/g squid, 2.78±0.29 mg/g dover sole, 3.69±0.06 mg/g albacore, and 4.18±0.10 mg/g bocaccio.     

Fast concentration of dissolved forms of cesium radioisotopes from large seawater samples

The method developed for cesium concentration from large freshwater samples was tested and adapted for analysis of cesium radionuclides in seawater. Concentration of dissolved forms of cesium in large seawater samples (about 100 L) was performed using composite absorbers AMP-PAN and KNiFC-PAN with ammonium molybdophosphate and potassium–nickel hexacyanoferrate(II) as active components, respectively, and polyacrylonitrile as a binding polymer. A specially designed chromatography column with bed volume (BV) 25 mL allowed fast flow rates of seawater (up to 1,200 BV h^?1). The recovery yields were determined by ICP-MS analysis of stable cesium added to seawater sample. Both absorbers proved usability for cesium concentration from large seawater samples. KNiFC-PAN material was slightly more effective in cesium concentration from acidified seawater (recovery yield around 93 % for 700 BV h^?1). This material showed similar efficiency in cesium concentration also from natural seawater. The activity concentrations of ¹³⁷Cs determined in seawater from the central Pacific Ocean were 1.5 ± 0.1 and 1.4 ± 0.1 Bq m^?3 for an offshore (January 2012) and a coastal (February 2012) locality, respectively, ¹³⁴Cs activities were below detection limit (<0.2 Bq m^?3).