Separation Of Radium Research Articles

Radium separation from thorium and manufacturing of targets by precipitation method

Radium separation from thorium and manufacturing of targets by precipitation method

Efficient separation of radium from natural thorium using a mesoporous silica-supported composite resin with sulfonic acid groups for the acquisition of targeted α-nuclides 212Pb

212Pb serves as one of the most important nuclides for targeted alpha therapy (TAT), with good potential in the treatment of malignant tumors. However, medical and clinical applications are seriously limited by its extremely short supply, which strongly depends on the acquisition of its parent nuclides such as 228Ra or 224Ra. To address this issue, we conducted a systematic investigation on the separation of trace radium from natural thorium using the ion exchange chromatography method, and a novel porous silica-based composite resin functionalized with sulfonic acid groups was prepared, characterized, and employed. Experimental results showed that the silica-supported resin was successfully prepared with the sulfonic acid groups, and possessed small particle size, mesoporous pore structure and large specific surface area. The resin exhibited high selectivity toward thorium compared with barium, and the separation factor reached 123 at low acidity and at low temperature. The resin demonstrated a fast adsorption speed and an excellent separation performance, and the adsorption mechanism was confirmed based on the ion exchange between the sodium carried and the target cations. On the basis, column experiments were further conducted and finally the separation of trace radium from thorium was realized using a small column filled with about 1.0 g resin. The chemical recovery of radium reached 97 %, and the decontamination factor for thorium exceeded 40,000. This work verifies the feasibility of directly extracting 228Ra and 224Ra from natural thorium using the sulfonic acid group functionalized materials in the dilute nitric acid solution, and presents an excellent material and systematic experimental data on the separation activities, rendering this study particularly significant.

Batch and column studies of radium, actinium, thorium and protactinium on CL resin in nitric acid, hydrochloric acid and hydrofluoric acid

CL resin (TrisKem International) was characterized for separations of radium, actinium, thorium and protactinium. Batch studies are presented for radium, actinium and thorium in HCl and HNO3 as well as for radium, thorium and protactinium in HF. The uptake of thorium from dilute HNO3 (≤ 10−4 M) and dilute HCl (≤ 10−4 M) was found to be very high (Dw > 100 in HNO3 and > 1000 in HCl). Kinetics studies on thorium were performed in HCl and HNO3 to determine suitably for column separations. Six column separation studies are presented including the separation of trace thorium from radium and actinium in dilute HCl and HNO3, the separation of radium from 1 mg 232Th in dilute HCl, the separation of thorium and radium in the presence of HCl and excess Cl−, the separation of radium, protactinium and thorium by retention of protactinium and the separation of protactinium and thorium by retention of thorium.

Metal Oxide Sorbents for the Separation of Radium and Actinium

The inorganic, normal-phase sorbents alumina, titania, and zirconia were evaluated and screened for the separation of Ba, La, 228Ra, 228Ac, and 212Pb in a dilute acid matrix. The results show that ...

The development of 228Ac isotopic generator

The paper describes a method of recovery of 228Ac tracer from an old thorium salt through sequential separation of 228Ra by sorption onto the MnO2-CTA disk from thorium solution followed by Ac/Ra separation using the Axionit 507 extraction chromatographic resin. It was shown that the optimal conditions of radium separation from thorium nitrate solution are pH 4.7–6.1 and EDTA as a complexing agent for thorium stabilization as Th4+ form at Th/EDTA molar ratio of 1:1. Since both 228Ra and 224Ra are separated from thorium solution, 25 days were calculated as the minimal time necessary for obtaining pure fraction of 228Ra. Separation of 228Ac from 228Ra generator solution by the Axionit 507 resin is possible at pH 2.4–2.9; actinium desorption can be performed by 4–10 mL of any mineral acid solution at pH 1–1.5. High selectivity of the Axionit 507 resin provided additional decontamination of 228Ra generator solution from 228Th. The 228Ac eluate with the average radionuclide purity of 98.8% containing no organic compounds and/or complexing agents was obtained.

Selective Separation of Radium and Actinium from Bulk Thorium Target Material

A complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material will be presented. The process may be applicable to the production of 225Ac and 227Ac via proton spallation on thorium targets. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Targeting the minor components (Ac,Ra) allows use of much smaller chromatographic columns than traditional nitrate based systems which target the bulk thorium. Additionally, the primary separation is performed from 0.1M Th, 0.6M sulfate, pH 1-2 instead of the more corrosive 3-8M HNO3 typically employed in solvent extraction or anion exchange based thorium separations. Actinium and radium are recovered from the cation exchange resin in a small volume of 5M HNO3 and directly purified via extraction chromatography with UTEVA and DGA resins without feed adjustment or evaporation. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity. The flowsheet has been tested at the Canadian Nuclear Laboratory (CNL) on 25 gram solid thorium targets irradiated at Fermi Lab. -Bond, A.H., Horwitz, E.P., McAlister, D.R., 2006. A Multicolumn Selectivity Inversion Generator for the Production of High Purity Actinium-225 for Use in Therapeutic Nuclear Medicine, United States patent number 7,087,206. (Licensed to NorthStar Medical Radioisotopes) -D.R. McAlister, E.P. Horwitz, “Selective Separation of Radium and Actinium from Bulk Thorium Target Material on Strong Acid Cation Exchange Resin from Sulfate Media,” Applied Radiation and Isotopes, 140, 18-23 (2018).

Selective Separation of Radium and Actinium from Bulk Thorium Target Material

A complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material will be presented. The process may be applicable to the production of 225Ac and 227Ac via proton spallation on thorium targets. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Targeting the minor components (Ac,Ra) allows use of much smaller chromatographic columns than traditional nitrate based systems which target the bulk thorium. Additionally, the primary separation is performed from 0.1M Th, 0.6M sulfate, pH 1-2 instead of the more corrosive 3-8M HNO3 typically employed in solvent extraction or anion exchange based thorium separations. Actinium and radium are recovered from the cation exchange resin in a small volume of 5M HNO3 and directly purified via extraction chromatography with UTEVA and DGA resins without feed adjustment or evaporation. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity. The flowsheet has been tested at the Canadian Nuclear Laboratory (CNL) on 25 gram solid thorium targets irradiated at Fermi Lab. -Bond, A.H., Horwitz, E.P., McAlister, D.R., 2006. A Multicolumn Selectivity Inversion Generator for the Production of High Purity Actinium-225 for Use in Therapeutic Nuclear Medicine, United States patent number 7,087,206. (Licensed to NorthStar Medical Radioisotopes) -D.R. McAlister, E.P. Horwitz, “Selective Separation of Radium and Actinium from Bulk Thorium Target Material on Strong Acid Cation Exchange Resin from Sulfate Media,” Applied Radiation and Isotopes, 140, 18-23 (2018).

Selective separation of radium and actinium from bulk thorium target material on strong acid cation exchange resin from sulfate media

This work presents a complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material, in a process that may be applied in a separation scheme for the production of 225Ac by proton spallation on thorium. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Following rinsing steps to remove residual thorium, actinium and radium are recovered from the cation exchange resin using 5 M HNO3. Further separations of actinium via extraction chromatography with UTEVA and DGA resins yield actinium in >92% yield, while providing additional decontamination from thorium and other spallation byproducts. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity.

Recovery of Ra-223 from natural thorium irradiated by protons

AbstractIrradiation of natural thorium with medium-energy protons is considered to be a prospective approach to large-scale production of225Ac and223Ra. In addition to the earlier-developed method of225Ac isolation, the present work focuses on the simultaneous recovery of.223Ra from the same thorium target. Radiochemical procedure is based on liquid-liquid extraction, cation exchange and extraction chromatography. The procedure provides separation of radium from spallation and fission products generated in the thorium target. High chemical yield (85– 90%) and radionuclide purity of223Ra (> 99.8% except224Raand225Ra isotopes) have been achieved.

Dissolution of [226Ra]BaSO4 and partial separation of 226Ra from radium/barium sulfate: A new treatment method for NORM waste from petroleum industry

Complete dissolution of [226Ra]BaSO4 precipitate was successfully performed using NaNO2 as a reducing agent in acidic solution at room temperature. Results showed a significant effect of acid and NaNO2 concentrations and temperature on the dissolution efficiency. The method was successfully used for separation of radium from NORM scale samples from the petroleum industry; sufficient volume reduction of NORM waste was achieved. The obtained 226Ra solution was purified using two separation methods. The dissolution method can be of great interest in the development of radiochemical analysis of radium isotopes.

Low-level 226Ra determination in groundwater by SF-ICP-MS: optimization of separation and pre-concentration methods

Abstract Background Inductively coupled plasma mass spectrometry (ICP-MS) techniques have been widely used for analysis of long-lived environmental radionuclides. In this paper, we present an optimization of the sector field (SF)-ICP-MS technique for the analysis of 226Ra in groundwater samples using a method of pre-concentration of radium in water samples. Methods The separation protocol and a sequential application of ion exchange and extraction chromatography have been optimized, and related polyatomic interferences and matrix effects affecting the 226Ra signal were investigated. Results Analyzing 12 replicates (water spiking at 22 fg g−1 of 226Ra), the 226Ra recovery efficiency close to 100 % has been obtained. The instrumental 226Ra detection limit of 0.09 fg g−1 (3σ criterion) and the absolute detection limit of 0.05 fg in a 25-mL groundwater sample have been reached. Conclusions An optimization of the radium separation method and a pre-concentration of radium in groundwater samples led to high radium recoveries, almost up to 100 %. The same could be said with respect to the separation of the interfering elements, important for the quantitative 226Ra analysis by SF-ICP-MS. The improvements in the separation and pre-concentration techniques also helped to improve the 226Ra detection limit down to 0.05 fg/25 mL of groundwater sample.

Analysis of radium-226 in high salinity wastewater from unconventional gas extraction by inductively coupled plasma-mass spectrometry.

Elevated concentration of naturally occurring radioactive material (NORM) in wastewater generated from Marcellus Shale gas extraction is of great concern due to potential environmental and public health impacts. Development of a rapid and robust method for analysis of Ra-226, which is the major NORM component in this water, is critical for the selection of appropriate management approaches to properly address regulatory and public concerns. Traditional methods for Ra-226 determination require long sample holding time or long detection time. A novel method combining Inductively Coupled Mass Spectrometry (ICP-MS) with solid-phase extraction (SPE) to separate and purify radium isotopes from the matrix elements in high salinity solutions is developed in this study. This method reduces analysis time while maintaining requisite precision and detection limit. Radium separation is accomplished using a combination of a strong-acid cation exchange resin to separate barium and radium from other ions in the solution and a strontium-specific resin to isolate radium from barium and obtain a sample suitable for analysis by ICP-MS. Method optimization achieved high radium recovery (101 ± 6% for standard mode and 97 ± 7% for collision mode) for synthetic Marcellus Shale wastewater (MSW) samples with total dissolved solids as high as 171,000 mg/L. Ra-226 concentration in actual MSW samples with TDS as high as 415,000 mg/L measured using ICP-MS matched very well with the results from gamma spectrometry. The Ra-226 analysis method developed in this study requires several hours for sample preparation and several minutes for analysis with the detection limit of 100 pCi/L with RSD of 45% (standard mode) and 67% (collision mode). The RSD decreased to below 15% when Ra-226 concentration increased over 500 pCi/L.

228Ra and 226Ra measurement on a BaSO4 co-precipitation source

One of the most commonly-used methods for determination of 226Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO4, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO4 co-precipitation methods which enable determination of 228Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for 226Ra, and can be used for re-analysis of already existing sources prepared by BaSO4 co-precipitation. The first adaptation uses detection of 228Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As 228Ac grows in quickly, taking less than 2 days to reach equilibrium with the 228Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO4 sources, allowing separation of thorium and subsequent determination of 228Th activity. Although ingrowth periods for 228Th can be lengthy, very low detection limits for 228Ra can be achieved with this technique.

Selective separation of radium and uranium from aqueous solutions by Chelex-100

The affinity of Chelex-100 for radium has been investigated as a function of pH and salinity compared to the Chelex-100 affinity for uranium to assess possible application of the resin for the selective separation of the two naturally occurring radionuclides from aqueous solutions. According to the experimental data the maximum chemical recovery of Chelex-100 is observed for uranium at pH 5 and for radium at pH 3 indicating a pH controlled selectivity of the resin for the two radionuclides. Moreover, the effect of salinity on the chemical recovery of radium is significant, resulting in a dramatic decrease of the former with increasing salinity. On the other hand, there is almost no effect of the salinity on the chemical recovery of uranium, indicating the higher affinity of Chelex-100 for uranium, which could be attributed to the formation of inner-sphere complexes of U(VI) with the iminoacetic moieties of the resin. The method has been successfully applied for the uranium separation from a radionuclide mixture.

High precision determination of 228Ra and 228Ra/ 226Ra isotope ratio in natural waters by MC-ICPMS

A new methodology has been developed for precise and accurate determination of 228Ra and the radium isotope ratio ( 228Ra/ 226Ra) by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) in natural water. The method was tested on waters from Lake Kinneret (The Sea of Galilee) and saline springs that flow into it. The radium is pre-concentrated from 60 L of Lake Kinneret water (or 2 L of the saline springs water) by co-precipitation with MnO 2. The separation of radium from the matrix elements was conducted by BioRad ® AG50W-X8 and Sr Spec ® resins. The instrumental limit of detection for 226Ra and 228Ra was 5 fg mL −1 (0.05 ppq) or 0.1 and 30 dpm L −1, respectively, and the absolute limit of detection 0.005 fg. Internal precision of the radium isotope ratio ( 228Ra/ 226Ra) in Lake Kinneret for 228Ra concentration as low as 0.10 fg L −1 (0.06 dpm L −1) was 2.8% (2 σ) and external precision was 10% (2 σ, n = 9).

Nanofiltration and low energy reverse osmosis in rejection of radioactive isotopes and heavy metal cations from drinking water sources

While nanofiltration (NF) and low energy reverse osmosis (LERO) have only moderate rejection for monovalent salts, they have been shown to be highly effective in water dehardening and in removal of polyvalent contaminant ion species. The present work is a part of a long-term investigation of the treatment of contaminated ground waters and certain grades of industrial waste waters for rejection of radioactive isotopes and heavy metal cations (HMC) and for determination of efficient and environmentally safe waste disposal methods. In fact several technical challenges remain with regards to the efficiency and cost of conventional methods for removal of certain contaminants, NF is thought to offer higher efficiency and lead to lower cost. Separation of radium (Ra 2+ 226 and Ra 2+ 228), uranium 238 (UO 2+ 2 or its carbonate complex anions at pH 7.5 to 8,UO 2 (CO 3 ) 2- 2 /UO 2 (CO 3 ) 4- 3 , Cd 2+ , Cu 2+ , Hg 2+ and other cations from mixture salt solutions was investigated as a function of water composition and concentration by NF and LERO. Results were compared to those of separation by conventional methods of chemical precipitation, softening with the hot lime method (HLM), coagulation, and separation by chelating ion-exchange resins (IERs) determined under the same conditions. Membrane methods gave higher rejection of radionuclides and HMCs ranging from 92% to 99%. Contaminant concentration in permeate water was lowered than the maximum contaminant level (MCL) of the US Environmental Protection Agency at system recoveries which attained 90%. In case of separation by IERs a loss of process efficiency which attained 24% was observed in view of interference with separation of similar valency ions such as Ca 2+ and SO 2- 4 . The higher the efficiency of the resin to retain the radionuclide, the more its regeneration was difficult, resulting in a higher volume of contaminated spent solution. With NF and LERO, on the other hand, parallel rejection of polyvalent ions did not practically impact that of radionuclides or HMCs, and membranes do not require regeneration. Results of rejection of radionuclides and HMCs showed several significant advantages of membrane methods over that by IER, coagulation, chemical precipitation, and softening. These are the absence of chemical dosing specific to rejection, absence of sludge formation which is contaminated and requires disposal, mechanism does not include slow steps like settling, no need of subsequent filtration or of expensive installations, and the ability to realize parallel water desalination. The study will extend to the evaluation of the waste disposal alternatives. In view of the concentration of the contaminants in the waste stream, selection of environmentally safe disposal methods will be determined.

Development of an MSFIA-MPFS pre-treatment method for radium determination in water samples

A new automatic method for preconcentration and separation of radium in water samples has been developed. Such method combines both multisyringe (MSFIA) and multi-pumping (MPFS) flow analysis techniques allowing to analyze larger sample volumes with a higher throughput than other previous methodologies. Ra adsorbed on MnO 2, deposited on cotton fiber, is eluted with hydroxylamine and subsequently coprecipitated with BaSO 4. 226Ra activity is determined off-line by using a low background proportional counter. The procedure yield is (90 ± 3)% and its lower limit of detection 0.05 Bq L −1. This method has been applied satisfactorily to different types of spiked water (tap, mineral and seawater).

Determination of 226Ra at ultratrace level in mineral water samples by sector field inductively coupled plasma mass spectrometry

An analytical procedure has been proposed for the determination of (226)Ra at the low femtogram per ml concentration level in mineral water samples using double focusing sector field ICP-MS (ICP-SFMS). For the pre-concentration and separation of radium from the matrix elements in water a tandem of a laboratory-prepared filter, based on MnO(2), and Eichrom "Sr-specific" resin was used. The recovery of the method was determined to be 70.5%. The limit of detection for (226)Ra determination was 0.02 fg ml(-1), including a pre-concentration factor of 10. In addition, uranium concentration and uranium isotope ratios were measured by ICP-SFMS. In several mineral water samples with a relatively high uranium content, (226)Ra concentrations were found between 0.7-15 fg ml(-1). The effective dose of the contribution was calculated using the radionuclide concentration and dose conversion factors from the World Health Organization, WHO (1993). Assuming a mineral water consumption of 2 l d(-1), a slightly higher calculated dose than the suggested limit for drinking water (0.1 mSv y(-1)) was found in some samples.

Separation of radium in the reaction of 60 MeV/u 18O with ThO2

230Ra and its daughter 230Ac were produced by the reaction of 60 MeV/u 18O with ThO2. Using 133Ba, 224Ra and 212Pb–212Bi as tracers, 0.1M NH4EDTA–0.3M NH4-acetate solution as eluent, the relationship between pH and elution peaks, and the influence of the amount of Ba2+ carrier on the elution curve in cation exchange procedures were tested. Based on the results of conditional experiments, a procedure suitable for isolation of radium from the ThO2 irradiated with 60 MeV/u 18O beam was developed. The results demonstrated that the decontamination effectiveness for main reaction products, specially for barium, was satisfactory.

An easy method for Ra-226 determination in river waters by liquid-scintillation counting

226Ra activity concentration in river water was determined using a low background liquid scintillation counter. Radium was extracted from the samples as Ra-BaSO4 precipitate which, afterwards, was dissolved with EDTA in ammonia medium. Solution was transferred into a low potassium glass vial and then mixed with a scintillation cocktail. Two different scintillation cocktails were selected for comparison. Efficiency, recovery yield and α/β separation were studied with both liquid scintillation cocktails. One single measurement, made one month after radium separation, allows to calculate the226Ra concentration as well as to assess the presence of alpha contamination of the sample. In the case of negligible interferences,224Ra concentrations can be subsequently evaluated in the same sample by the measurement made just after chemical separation of radium. This method has been applied for the determination of226Ra and224Ra activity concentrations in river water collected from different locations along the Odiel river estuary area (South-west of Spain). The presence of chemical industry, the wastes of which are released into the river, could be connected with radium activity concentration enhancements in the water.