Recovery Of Strontium Research Articles

Sorption Recovery of Strontium from Seawater

Sorption recovery of strontium from seawater and prospects of using selective sorbents for treatment of seawater or mixtures of liquid radioactive wastes (LRW) with seawater to remove 90Sr are examined. A comparative analysis is made of characteristics of various sorbents. The most of the sorbents studied demonstrate low distribution coefficients and selectivity with respect to strontium, being unable to provide efficient removal of 90Sr from seawater. The exceptions are new sorption reagents developed by the authors, which show promise for treatment of LRW to remove strontium. The possible mechanism of strontium sorption with these sorbents is suggested.

Preparation of strontium carbonate from celestite

A novel method for the preparation of strontium carbonate from celestite ore has been investigated. The ore is reduced by brown coal at a temperature of 1000°C for a period of 3 h. The reduced product is leached with water at a liquid : solid ratio of 3 : 1 at 90°C and the slurry is then leached with hydrochloric acid at a solid : liquid ratio of 2 : 1. By controlling the pH at 1.5-2 and adding 20% H2O2 at the rate of 0.5 dm3/m3 of solution the oxidation process HS-→So is accomplished. Barium is precipitated with dilute sulphuric acid; and more than 90% Ca2+ + Mg2+ (and Fe) is removed when the pH is increased to 12. Addition of 1.2 times the theoretically required amount of NH4HCO3 at a solution strength of 2 mol/l at 60°C and at pH in the range 9-11 results in the precipitation of SrCO3. The precipitate is washed and dried at 220-250°C. The proposed flowsheet is simple, has low consumption of acid and alkaline reagents, gives a high recovery of strontium and accepts a wide range of raw material.

Strontium and Calcium Complexation by Humic Acid

The binding of strontium by humic acid was studied in systems designed to model soil leaching conditions. Ultrafiltration experiments were conducted for a wide range of CaCl and NaCl concentrations and for the pH range 4 to 7. It was found that the recovery of humic acid slowly decreased with increasing pH. This occurred because at neutral and basic solutions the increasing degree of ionization of the carboxylate groups leads to the full repulsion state of the humic acid and to increasing of the strontium binding (strontium recovery ∼60% at pH 7) with this natural polyelectrolyte. The strontium complexation in the presence of calcium was studied in different series of metal concentrations at pH 5 and the ionic strength 0.1M NaCl. The results were explained on the base of the metal ion charge neutralization model of humic complexation (CNM). Loading capacity (cca 40%) and complexation constants and Sr (3.51±0.27) and Ca (3.10±0.29) with Aldrich humic acid were found.

A process for the recovery of strontium from the urine of patients injected with 89Sr

89Sr is a beta used for palliation of pain in patients with metastatic bone cancer. After each intravenous administration, up to 80% of the isotope is eliminated in the urine. A simple chemical process is described, which permits the recovery and purification of the 89Sr from the urine.

The leaching of SrS with water and the precipitation of SrCO 3 from leach solution by different carbonating agents

The leaching of strontium sulfide (SrS) with water was investigated, and a comparison of Na 2CO 3 with CO 2 as a carbonating agent for the precipitation of SrCO 3 from leach solution was done. The effects of variables for leaching—temperature, retention time and solid to liquid ratio, and the effects of variables for precipitation—carbonation time, temperature, amount of carbonating agent and addition of oxygen to carbon dioxide, were studied. It was concluded that leaching of strontium sulfide is mainly dependent on the solubility of strontium hydroxide; however, SrS decomposes easily in hot water to give the hydrosulfide and the hydroxide. As a carbonating agent, Na 2CO 3 provides higher precipitation rates and higher strontium recovery but low SrCO 3 grade, whereas precipitation with CO 2 gives a high purity of product which is sufficient for most of the uses of SrCO 3. It was also found that oxygen, when used together with carbon dioxide in the carbonation column, increases the strontium recovery and decreases the carbonation time.

EVALUATION OF SYNTHETIC INORGANIC ION EXCHANGERS FOR CESIUM AND STRONTIUM REMOVAL FROM CONTAMINATED GROUNDWATER AND WASTEWATER

ABSTRACT The ion exchange testing of 30 synthetic adsorbents including layered and framework polyvalent metal silicates and phosphates, as well as amorphous exchangers was carried out. Their selectivity to alkali and alkaline earth metal cations in individual and complex solutions was determined. Several exchangers were found to have high selectivity for cesium and strontium. These exchangers are sodium phlogopite, layered sodium titanium silicate Na2TiSi2O7·2H2O, framework niobium (Na2Nb4Si2O15·4H2O, tentative formula), zirconium (Na2ZrSi3O9·H2O) and titanium (Na2Ti2SiO7·2H2O) silicates, and a layered δ-tin phosphate (Sn(HPO4)·2H2O). For all these materials cesium and strontium ion exchange capacities as a function of pH were determined. The effect of sodium, magnesium and calcium on Cs− and Sr2− ions sorption was also studied over the concentration range 0.005 M - 1 0 M and the explanations for the phenomena observed were proposed based on the knowledge of the crystal structure of the exchangers. Testing of the most promising exchangers for selective cesium and strontium recovery from ground water simulant in batch regime was carried out.

Extraction of Strontium from Acidic Nitrate Media Using a Modified PUREX Solvent∗

ABSTRACT A new process for the extraction and recovery of strontium from acidic waste streams is described. In this process, a modification of the previously described SREX (for strontium extraction) process, strontium is extracted from acidic (≥ 2 M nitric acid) solution using a 0.2 M solution of di-t-butylcyclohexano-18-crown-6 in any of a variety of phase modifier / paraffinic hydrocarbon mixtures, among them a PUREX-like diluent comprised of a 1.2 M solution of tri-n-butyl-phosphate in Isopar L. Tests of this process solvent on a synthetic dissolved sludge waste show that only strontium and barium are appreciably extracted by the crown ether under the experimental conditions. As expected, uranium and plutonium are extracted even in the absence of the crown ether.

Preconcentration of strontium by micelle modified solid phase extraction

The preconcentration of strontium using a solid phase separation technique with selective micelle forming complexant has been studied. Di-2-ethylhexylphosphoric acid and its thio- and dithio derivatives were used as modifiers. The goal of this work was to study the influence of physico-chemical parameters on recovery of strontium after its preconcentration on reverse phase (Si−C-18) using micelle modifiers.

Precipitation separation of strontium and calcium from acidic solutions using crown ether and tungstosilicic acid

Strontium forms a compound of composition (SrL)2A·nH2O with low solubility (5.0·10−6 mol Sr·dm−3) in the presence of 18-crown-6 (L) and tungstosilicic acid (H4A) in acid media, as has been found by radiometric precipitation titration. Formation of the compound with limited solubility was used for separation of strontium and calcium from 1 mol·dm−3 HCl. It is possible to separate strontium in the range from trace to 6 mmol·dm−3 in the presence of calcium with its concentration up to 0.2 mol ·dm−3 and the recovery determined was 95% of Sr and 5% Ca or 90% of Sr and 4% Ca, respectively. The ratio of Sr/Ca depends on the stability constants ratio of metal-L (²SR/²ca) in the case of gradual addition of L. Potassium up to the concentration of 0.05 mol·dm−3 does not influence recovery of strontium.

Under-determination of strontium-90 in soils containing particles of irradiated uranium oxide fuel

A much used method for the determination of 90Sr in soil depends on extraction of the soil with 6 mol l–1 HCl, followed by β-counting. For soils containing particles of irradiated uranium oxide, we postulate that this extraction could result in a variable underestimate owing to incomplete chemical recovery of strontium from the uranium oxide matrix. In experiments on two soils, collected from near Windscale (now Sellafield) in 1956 and near Chernobyl in 1990, about 25% of the total 90Sr present in the soil was recovered in 24 h by HCl extraction at room temperature, and the presence of high-radioactivity particles both before and after extraction was demonstrated by autoradiography. For a further 11 particle-containing Chernobyl soils, 90Sr determination, based on classical HCl extraction, yielded, on average, 54%(range 33–85%) of the total 90Sr, as determined by oxidative alkaline fusion. While we accept that HCl extraction is well established as a reliable method for the determination of soil 90Sr derived from weapons fallout, we conclude that more rigorous analytical pre-treatment is essential in instances where the 90Sr may be associated with fuel particles.

Counter-current ion-exchange separation of strontium from brines with acrylic-type cation-exchange resins

To solve the problem of strontium recovery from brines, polyacrylic acid cation-exchangers were used. Extraction of Sr 2+ from the Na +, Ca 2+ and Sr 2+ mixture was accomplished in a counter-current column into which the cation-exchanger (Na + form) and the salt solution to be separated were fed. A zone formed in the column, adjacent to the sorption front of the divalent ions, where the solution and the ion-exchanger contained concentrated strontium, separated from calcium. The solution from this zone was collected and the Sr 2+ ions were eluted from the ion-exchanger in a second counter-current column by a sodium solution containing calcium. The solution eluted from the second column was returned to the first separation column and the ion-exchanger was further regenerated from the mixed Ca 2+ and Na + form to the Na + form and returned to the separation column. All stages of the process were operated continuously and simultaneously. The extent of strontium extraction was about 98%.

Strontium Extraction by Aluminothermic Reduction

AbstractExperiments are performed in a mechanically agitated molten bath of aluminium to extract strontium from strontium carbonate by aluminothermic reduction. The molten aluminium contains additions of magnesium or bismuth. Magnesium is added to the melt for two reasons: to increase the reactivity and to lower the surface tension of the molten alloy. Bismuth is added to lower the surface tension without altering the reactivity of the melt. The experimental conditions are: temperature, 1000°C; pressure, 1 atm; contacting time, 1 h. Results show that with a Mg:Sr molar ratio of 10:1, strontium recovery from the strontium carbonate feed to the excess aluminium is greater than 50% Comparison between experiments with either magnesium or bismuth additions shows that the chemical effect of magnesium is predominant over the surface tension effect of bismuth or magnesium. Resume Des essais ont ete realises afin d'extraire par reduction aluminothermique le strontium du carbonate de strontium a l'interieur d'un ba...

SREX: A NEWPROCESS FOR THE EXTRACTION AND RECOVERY OF STRONTIUM FROM ACIDIC NUCLEAR WASTE STREAMS

ABSTRACT A new process for the extraction and recovery of strontium from acidic waste streams is described. In this process, called SREX (for Strontium Extraction), strontium is extracted from acidic ( ≥ 1 M HNO3) solution using a 0.20M solution of di-t-butylcyclohexano-18-crown-6 in 1-octanol. Extracted strontium is readily stripped from the organic phase using either water or dilute (<0.05 M) HNO3. Tests of the process on a synthetic dissolved sludge waste solution show that only strontium, barium, and technetium are appreciably extracted by the crown ether. Prolonged exposure of the process solvent to nitric acid at elevated temperatures or to ≤ 50 Wh/L γ radiation from a 60Co source produces essentially no deterioration in its performance. Benchtop batch countercurrent extraction experiments show that 99.7% of the strontium initially present in a feed solution can be removed in only three extraction stages.

REMOVAL OF FUMING NITRIC ACID VAPOR IN THE RADIOCHEMICAL DETERMINATION OF STRONTIUM

A safety separation of strontium from calcium substituted for the conventional dropwise addition of fuming nitric acid to the 90 Sr analyte solution was developed, based on addition of fuming nitric acid all at once to the solution, sealed with a thin film and then stirred. Decontamination and recovery of strontium of present procedure was virtually the same as those of the conventional procedure. The former prevents the external release of toxic fuming nitrogen dioxide vapor from the analyte solution, which contribute significantly to safety handling in view of radiochemical determination of strontium

Ion chromatographic separation for analysis of radiostrontium in nuclear reprocessing solutions of high ionic strength

Determination of90Sr in nuclear fuel reprocessing solutions can be facilitated by a preparatory separation using analytical ion chromatography (IC). Furthermore, a novel acid suppression system is described which permits IC separation even in the presence of very strong (0.33M) acid. Following acid suppression (where needed), Sr2+ is concentrated and separated from most other solution components by selective adsorption on cation concentrator columns. Cation species retained on the concentrator columns with strontium are subsequently separated on a cation IC column. The Sr2+ peak aliquot is collected for subsequent radiostrontium analysis by liquid scintillation counting of the beta activity. Results have shown quantitative separation and recovery of strontium. The entire separation system is automated under computer control and is able to handle samples of large (500 ml) and small (μl) sizes.

Effect of ultrasonication on extraction rate and on recovery of strontium from river sediment using flame atomic absorption spectrometry

The effects of ultrasonication on the selective extraction of adsorbed Sr and the recovery of total Sr from river sediment have been investigated using flame atomic absorption spectrometry. Results from ultrasonic extraction (UE) experiments were comparable to those of conventional procedures for adsorbed Sr but results for the recovery of total Sr in the river sediment were not satisfactory. The precision obtained from 13 replicate UEs yielded an average relative standard deviation of 11.8% for adsorbed Sr. The recoveries of total Sr from NIES certified reference material 2 (a pond sediment standard from the National Institute for Environmental Studies, Japan) using UE ranged from 65 to 107% with respect to the reference value.

THE EXTRACTION OF CESIUM AND STRONTIUM FROM ACIDIC HIGH ACTIVITY NUCLEAR WASTE USING A PUREX PROCESS COMPATIBLE ORGANIC EXTRACTANT

Purex process compatible organic systems which selectively and reversibly extract cesium and strontium from synthetic mixed fission product solutions containing3M HNO3, have been developed. This advance makes the development of continuous solvent extraction processes for their recovery more likely. The matrix solution from the Purex process consists of tributyl phosphate (TBP) and kerosene. For cesium and strontium recovery a macrocyclic polyether (crown compound) has been developed for each element. When used in conjunction with a liquid cation exchanger in the matrix solution, the crown compounds will extract either alkali metals or alkaline earths from the synthetic mixed fission product solution. The organic cation exchangers used in this research were didodecylnaphthalene sulfonic acid (DNS) and dinonylnaphthalene sulfonic acid (NNS). As was expected both zirconium and ruthenium also tend to be extracted due to the TBP in the matrix solution and to their complex chemistry. The most favorable cesium a...

The preparation of a rubidium-82 radionuclide generator

Abstract 82Sr has now been produced by the spallation of Molybdenum by protons of up to 800 MeV. The radiochemical recovery of strontium is described together with a description of the analytical techniques used to estimate recovered yields of the various radionuclides generated. A radionuclide generator is described for the rapid recovery of82Rb, the 1.25 min half-life decay product of82Sr. An outline is given of the quality control procedure adopted to ensure that the82Rb is suitable for clinical use.

Separation of strontium-89 and -90 from calcium in milk with a macrocyclic ether.

A small amount of strontium ion (20 mg) was simply separated from a large amount of calcium ion (0.5 to 13.6 g) by liquid--liquid extraction using dicyclohexyl 18-crown-6 chloroform solution. The extraction was applied to a part of the procedure for determining radiostrontium in ash of milk. The overall recovery of strontium was 75% on the average for 5 to 10 g of milk ash. Decontamination factors for Mg, Ca, Ru, I, Cs, Ba, and La in the final fraction were 1 x 10/sup 5/, 1 x 10/sup 4/, > 1 x 10/sup 6/, > 1 x 10/sup 6/, > 2 x 10/sup 6/, 2 x 10/sup 5/, and 3 x 10/sup 4/, respectively. The chemical procedure for three samples took about 2 days. 1 figure, 3 tables.

Carrier Determination in Radiostrontium Analyses Using Strontium-85

AbstractA radiometric method has been developed for determining strontium recovery in strontium-89 and strontium-90 analyses. This method makes possible the effective determination of strontium-85 in the presence of strontium-89 and -90 and vice versa. The strontium-85 activity per sample varies dir