Sorption Of Sr Research Articles

Fabrication of cobalt iron oxide alginate nanocomposite as an eco-friendly sorbent for Y(III) and Sr(II) removal from aqueous solution

Alginate cobalt iron oxide, Alg-CoFe2O4 nanocomposite was synthesized by ionic polymerization method and employed as a magnetically separable low-cost sorbent for yttrium and strontium removal from an aqueous phase. The produced nanocomposite was characterized using x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The hysteresis loop of the nanocomposite, obtained by the vibrating sample magnetometer, shows a soft magnetic behavior with a saturation magnetization of about 6.96 emu/g. The optimum pH for the sorption of Y(III) and Sr(II), studied by the batch mode, was found to be 4.7 and that ion exchange is not the only mechanism in the sorption process. The obtained kinetic data of Y(III) and Sr(II) was analyzed using the reaction rate and diffusion models and it was found that the pseudo-second-order fits well the data with a high correlation coefficient > 0.99. The isotherm study revealed that the sorption of Y(III) was well described by the Freundlich model, whereas the Langmuir model provided the best fit for the sorption of Sr(II).The maximum sorption capacity of the nanocomposite was 78.22 mg/g for Y(III) and 47.5 mg/g for Sr(II). Furthermore, Y(III) and Sr(II) were recovered from the loaded nanocomposite with a high desorption percentage using 1.0 mol/L of HNO3 demonstrating its reusability. It can be concluded based on the results that the Alg-CoFe2O4 nanocomposite has good sorption potential of Y(III) and Sr(II).

Sorption of 90Sr by a T-3K carbonate-containing zirconium dioxide

Sorption of 90Sr by a T-3K carbonate-containing zirconium dioxide

Fate and transport of strontium in groundwater from a layered sedimentary aquifer system

In this article, strontium distribution in sedimentary coastal aquifers of Eastern India was studied and its association with groundwater particles has been ascertained using hydrochemical and morphological tools. Groundwater contains Sr2+ in the range of 0.08–4.0 mg/L with higher concentrations in Cretaceous formation. The particle number in groundwater varies from 4.5 × 105 to 3.3 × 106 per liter and follows the power law distribution with respect to the particle diameter. The calculated β values (2.54 and 4.03) signify the abundance of smaller particles over larger ones. The particle concentration of size range 0.45–8 μm is found to be 0.64–2.6 mg/L. Elemental data of groundwater particles clearly suggest their origin from the host rock minerals. Zeta potential data indicates diverse nature of colloids suggesting prevalence of both positive and negative charged species in the groundwater. The hydrochemical interpretation along with speciation studies infers that high Sr2+ in groundwater is a result of incongruent dissolution of carbonate minerals and the dissolved Sr2+ partitions into both dissociated and un-dissociated forms. Based on the Sr2+/Ca2+ ratio and mineral saturation indices, it can be inferred that the Sr2+ is preferentially associated with colloids over large particles and the migration takes place through sorption of Sr2+ onto clay-bound (extrinsic) colloids in groundwater. This study describes the mechanism of strontium release into groundwater and provides insights into the role of groundwater particles in controlling the strontium migration to deep aquifers.

A Study of Sr Sorption Behavior in Claystone from a Candidate High-Level Radioactive Waste Geological Disposal Site under the Action of FeOOH Colloids.

Colloids have a significant influence on the migration of nuclides in claystone, which is an important geological barrier. The sorption of strontium on claystone in the presence of FeOOH colloids was investigated in samples from the Suhongtu site, a candidate high-level radioactive waste disposal site in China. The effects of colloid amount, solid content, and pH were investigated by batch tests, and the sorption reaction mechanism was analyzed by kinetic modeling and microscopic characterization techniques. The results indicate that the sorption of Sr by claystone increased with the solids content, and the claystone had a stronger Sr sorption capacity under alkaline conditions. The Sr sorption kinetics were best described by the pseudo-first-order and pseudo-second-order models, which revealed that the progress is affected by physical diffusion and chemical sorption. Furthermore, the microscopic characterization results demonstrate that cation exchange reactions and surface complex reactions are the main sorption mechanisms for Sr sorption on claystone. Ca and Mg plasmas in claystone minerals can have cation replacement reactions with Sr, and functional groups such as -OH and [CO3]2− can have complexation reactions with Sr to adsorb Sr on the surface of the claystone. Additionally, the presence of the FeOOH colloid inhibited the sorption effect of claystone slightly. The FeOOH colloid could occupy sorption sites on the claystone surface, which reduces the activity of the functional groups and inhibits the sorption of Sr on claystone.

Adsorption of Cs(I) and Sr(II) on Bentonites with Different Compositions at Different pH

This paper deals with adsorption regularities and mechanisms of nonradioactive Cs(I) and Sr(II) analogs on bentonites of different chemical and mineral composition from solutions of Cs and Sr nitrates with pH 3, 7, and 10 units at constant ionic strength. The bentonites were taken from the deposits Taganskoe (T), Dash-Salakhlinskoe (DS), Zyryanskoe (Z), and 10th Khutor (10H). The pH of bentonite aqueous suspensions, T and DS, exceeded 9 units. A less alkaline reaction was observed in bentonite suspensions Z and T with pH 8.94 and 7.70, respectively. Bentonites T and DS contained significant amounts of nonsilicate iron compounds, 1.0 and 0.5%, respectively. The recovery rate of the studied clays from aqueous solutions of Cs(I) and Sr(II) ions in concentrations from 0.25 to 5 mmol/L varied from 50% to 90% and decreased in the following order: “Ta-ganskoe” > “Dash-Salakhlinskoe” > “Zyryanskoe” > “10th Khutor” in the studied pH range. The main mechanism of Cs(I) and Sr(II) sorption in the studied pH range was cation fixation in the form of outer-sphere complexes on planar surfaces resulting from ion exchange. Increasing pH (pH > 6) enhanced pH-dependent positions, which allowed Cs(I) and especially Sr(II) ions to fix on them more firmly as inner-sphere complexes. At pH 9–10, Sr(II) could precipitate in the form of carbonates. The sorption of Cs(I) + and Sr(II) was accompanied by competitive interactions with proton at pH < 6 and Na+, Ca2+, Mg2+, and K+ cations at higher pH values. This competition was more apparent at concentrations of Cs(I)and Sr(II) in initial solutions < 0.5 mmol/L. The ability of bentonite T to sorb Cs(I) and Sr(II) in large amounts compared to the other bentonites was determined by high CEC values and charge of smectite T.

Silico antimonate nanocomposite material: I- preparation, characterization and its application for separation of strontium and rubidium from aqueous solutions

ABSTRACT Sorption of Sr(II) and/or Rb(I) onto synthesised silico antimonate (SiSb) nanocomposite was investigated in this work, using batch equilibrium and column techniques. SiSb was fabricated by precipitation technique and characterised by various analytical tools. The adsorption of Sr(II) and/or Rb(I) includes the influence of shaking time, distribution coefficient, kinetics, capacity, and column separation. The data prove that SiSb has a quick equilibrium time (40 min), the distribution coefficients (Kd) as a function of pH have maximum separation factors ( α R b S r ) equal to 162.1 at pH 6, reaction kinetics follow a pseudo-second-order model, sorption capacity for Sr(II) and Rb(I) is 48.5 and 13.8 mg/g, respectively. Column data reveal that Sr(II) can be loaded and separated from Sr(II)-Rb(I) as a simulation model for Sr(II) recovery from its Sr(II)-Rb(I) system using different concentrations of HNO3 as eluent.

Sorption of Sr on montmorillonite clays: Theoretical and experimental study

Montmorillonite is a clay mineral widely used to remove pollutants from wastewater. The Sr sorption on montmorillonite was analyzed combining an experimental - theoretical approach. Sr sorption on natural and synthetic Na-montmorillonite was studied, characterizing the materials before and after Sr incorporation by X-ray diffraction and Zeta potential. The total specific surface area was also determined. Besides, ab-initio calculations were performed in order to investigate the sorption stability of the clay. The effect of the hydration of Sr atoms and the influence of the van der Waals interaction were evaluated. The experimental results indicated that Sr was sorbed on both, external and internal surfaces and that the total specific surface area seems to be relevant for the sorption process. The increasing in the interlayer space by Sr incorporation was associated with the cationic exchange, the hydration of the Sr atom and the relative humidity. Nuclear magnetic resonance parameters were calculated and compared with the experimental chemical shift and electric field gradient. The calculated Sr-chemical shift corresponds to the range for atomic coordination n = 6. Since there is no experimental data available for the principal component of the electric field gradient at Sr site, the obtained theoretical value stands as a prediction.

NanoTafla Nanocomposite as a Novel Low-Cost and Eco-Friendly Sorbent for Strontium and Europium Ions.

Now the wide use of nanooxides is attributed to their remarkable collection of properties. Nanocomposites have an impressive variety of important applications. A thermal decomposition approach provides a more optimistic method for nanocrystal synthesis due to the low cost, high efficiency, and expectations for large-scale production. Therefore, in this study a new eco-friendly nanooxide composite with sorption characteristics for europium (Eu(III)) and strontium (Sr(II)) was synthesized by a one-step thermal treatment process using earth-abundant tafla clay as a starting material to prepare a modified tafla (M-Taf) nanocomposite. The synthesized nancomposite was characterized by different techniques before and after sorption processes. Different factors that affected the sorption behavior of Eu(III) and Sr(II) in aqueous media by the M-Taf nanocomposite were studied. The results obtained illustrated that the kinetics of sorption of Eu(III) and Sr(II) by the M-Taf nanocomposite are obeyed according to the pseudo-second order and controlled by a Langmuir isotherm model with maximum sorption capacities (Qmax) of 25.5 and 23.36 mg/g for Eu(III) and Sr(II), respectively. Also, this novel low-cost and eco-friendly sorbent has promising properties and can be used to separate and retain some radionuclides in different applications.

Sorption of Strontium to Uraninite and Uranium(IV)-Silicate Nanoparticles.

Spent nuclear fuel contains both uranium (U) and high yield fission products, including strontium-90 (90Sr), a key radioactive contaminant at nuclear facilities. Both U and 90Sr will be present where spent nuclear fuel has been processed, including in storage ponds and tanks. However, the interactions between Sr and U phases under ambient conditions are not well understood. Over a pH range of 4–14, we investigate Sr sorption behavior in contact with two nuclear fuel cycle relevant U(IV) phases: nano-uraninite (UO2) and U(IV)–silicate nanoparticles. Nano-UO2 is a product of the anaerobic corrosion of metallic uranium fuel, and UO2 is also the predominant form of U in ceramic fuels. U(IV)–silicates form stable colloids under the neutral to alkaline pH conditions highly relevant to nuclear fuel storage ponds and geodisposal scenarios. In sorption experiments, Sr had the highest affinity for UO2, although significant Sr sorption also occurred to U(IV)–silicate phases at pH ≥ 6. Extended X-ray absorption fine structure (EXAFS) spectroscopy, transmission electron microscopy, and desorption data for the UO2 system suggested that Sr interacted with UO2 via a near surface, highly coordinated complex at pH ≥ 10. EXAFS measurements for the U(IV)–silicate samples showed outer-sphere Sr sorption dominated at acidic and near-neutral pH with intrinsic Sr-silicates forming at pH ≥ 12. These complex interactions of Sr with important U(IV) phases highlight a largely unrecognized control on 90Sr mobility in environments of relevance to spent nuclear fuel management and storage.

The study of 137Cs and 90Sr sorption by natural and modified aluminosilicates in presence of humic acids

The study of 137Cs and 90Sr sorption by natural and modified aluminosilicates in presence of humic acids

Adsorptive features of cesium and strontium ions on zirconium tin(IV) phosphate nanocomposite from aqueous solutions

ABSTRACT In this study, the sorption of Cs(I) and Sr(II) onto zirconium tin(IV) phosphate (ZrSnP) nanocomposite was achieved using the batch technique. ZrSnP has been prepared by the sol–gel technique and characterised using different analytical tools such as FT-IR, XRF, XRD, TGA & DTA, SEM, and TEM. The data obtained from this study showed that the sorption process was a fast equilibrium time (120 min). The distribution coefficients have sequence order; Cs(I) ˃ Sr(II). Reaction kinetic obeys the pseudo-second-order model. The capacity has the values 50.0, and 29.8 mg/g for Cs(I) and Sr(II), respectively. Sorption isotherms are more relevant to a Langmuir isotherm. Negative Gibbs energy values proved that the sorption process was spontaneous with high feasibility. Positive enthalpy values reveal that this process was endothermic. Positive entropy values showed that disorder between the solid–liquid phase increased during adsorption. The real sample study reveals that ZrSnP is a promising sorbent for the removal of 134Cs and 85Sr from low-level radioactive waste. The investigation proved that the ZrSnP is suitable for the removal of Cs(I) and Sr(II) from radioactive waste and could be considered potential material for purification of effluent polluted with these ions.

Studying the sorption of Sr and Ni ions from natural water on a ferritized zeolite-containing tuff of the Kholinskoe deposit

Studying the sorption of Sr and Ni ions from natural water on a ferritized zeolite-containing tuff of the Kholinskoe deposit

An application research for near-surface repository of strontium-90 sorption kinetic model on mudrocks

Abstract In this study,90Sr was used as the test radionuclide to characterize the sorption kinetics and effects of initial 90Sr activity and remaining 90Sr in solid concentration were simulated for a near-surface repository. The study focused on the sorption characteristics of radionuclides in unsaturated groundwater environment (or vadose zone) is the important information for investigating the near-surface disposal of intermediate and low-level radioactive waste (ILLW). Moreover, the 90Sr sorption experiments reached equilibrium within 56 h, which fit to the first order sorption kinetic model, and the remaining 90Sr in mudrock samples showed obvious sorption equilibrium hysteresis, which fit to the second order sorption kinetic model. Before reaching the maximum sorption capacity, the sorption rate constant increases with 90Sr increasing; the distribution coefficient (Kd) of 56 h decreases with the remaining 90Sr decreasing. In addition, it showed that the slow sorption process dominated before the sorption reaches equilibrium. In fact, a reliable safety assessment methodology for on-going near-surface repository required a lot of the radionuclides parameters with local environment including the radionuclides sorption/desorption rate constant and maximum sorption capacity.

Sorption of 137Cs and 90Sr on Organic Sorbents

The present study examines the sorption of Cs (I) and Sr (II) on organic sorbents in the pH range from 2 to 10, as well as the mechanisms of their binding. In order to determine the influence of the physical properties and the quantity of functional groups of the organic sorbents on sorption, experiments were carried out on organic materials of varying degrees of metamorphism: high-moor peat, hard and brown coals and shungite. A detailed description of their mineral composition, cation exchange capacity, buffering capacity and elemental composition of sorbents is provided. XRD, XRF, SEM and BET adsorption methods were used for assaying. As a result of the conducted research, it can be concluded that Sr (II) showed a higher sorption per unit specific surface area than Cs (I) in the studied range of concentrations and pH values. Sr (II) sorption decreases in the following order: high-moor peat > brown coal > shungite > hard coal. The sorption of Cs (I) is highest on brown coal and lesser for high-moor peat, shungite and hard coal. It is suggested that Cs (I) and Sr (II) can be fixed on carboxyl functional groups and Cs (I), possibly, in insignificant amounts on phenolic hydroxyls of all four studied organic sorbents.

Removal of europium, cobalt and strontium from water solutions using MnO(OH)-modified diatomite

The paper describes researches on new materials based on the MnO(OH)-modified diatomite synthesized for application in sorption of Eu, Co and Sr from aqueous solutions. The material was obtained through precipitation of MnO(OH) from initial solution on the surface of diatomite particles using MnO(OH) concentrations from 0.5 up to 10 wt%. Efficiency and sorption capacity were investigated, especially towards europium, cobalt and strontium solved in water. Since sorption efficiency of the pure diatomite is not high, it was demonstrated that its surface modification with MnO(OH) increased sorption capacity towards several heavy metals up to 95% and 98% in the range of pH between 4 and 8. Higher concentrations of MnO(OH) deposited on the diatomite particles surface increased sorption capacity. It was found that 1 wt% of MnO(OH) provided capacity 15, 10, and 17 mg/g towards Co, Eu, and Sr, respectively. Further, 10 wt% concentration of MnO(OH) ensured respective capacities toward the same elements 28, 16, and 64 mg/g. These results demonstrated capability of surface-modified with MnO(OH) diatomite particles to remove ions of divalent and trivalent metals out of the potable water.

Retention of strontium in high- & low-pH cementitious matrices – OPC vs. model systems

Strontium can be found in low/intermediate level radioactive waste streams, often solidified by Ordinary Portland Cement (OPC) matrices. Amorphous silica is added to improve wasteform performance, leading to low-pH systems. Our aim is to identify the phases controlling strontium immobilization in OPC matrices. The novelty of this work resides in combination between two approaches: 1) Comparing OPC systems to model systems based on alite, yielding matrices containing only major phases, emphasizing the relative role of minor phases; 2) Comparing high- & low-pH pastes. Pastes were characterized using calorimetry, XRD, DTG, SEM/EDS and porosimetry. Leaching experiments were conducted to study Sr retention and diffusivity. Strontium diffusivities in low-pH pastes are lower with respect to high-pH equivalents, despite their higher porosities, due to preferred Sr sorption to low Ca/Si C-S-H. OPC pastes show better Sr retention relative to model systems, suggesting that minor phases (like ettringite and AFm) improve Sr retention.

Experimental investigation on buffer/backfill materials for radioactive waste repository downward facing sorption additivity of cesium, strontium and cobalt with different concentrations

Abstract Buffer/backfill materials for radioactive waste disposal sites consist of pure bentonite or bentonite-rock mixtures. In this study, the batch test method was used to obtain the sorption characteristics of important radionuclides such as Cs, Sr and Co on buffer/backfill materials; i. e., mixing Wyoming MX-80 bentonite or local Taiwanese Zhi-Shin bentonite with possible host rock (argillite and granite) in different proportions (0∼100%). The distribution coefficients (Kd) for Cs, Sr and Co were obtained from the experiments. The distribution coefficient for the bentonite-rock mixtures were found, with more than 50% of mixing proportion of bentonite to argillite or granite, to have very similar values to that of pure bentonite. Furthermore, it was clearly found that the sorption of Cs, Sr and Co to bentonite-rock mixtures is decreased as ionic strength of the liquid phase is increased from 0.001M to 1M for NaCl solutions. According to the experimental results, in synthetic groundwater, it is quite convenient and helpful to assess the distribution coefficients (Kd) of Cs, Sr and Co for buffer/backfill materials using batch sorption experiments with bentonite-rock mixtures of fixed mixing proportions.

Correlation between chemical composition and 90Sr concentrations in groundwater of the Chornobyl NPP industrial site

The volumetric activity of the divalent 90Sr ion in groundwater at the Chornobyl NPP industrial site ranges from 1 to 2 to 400–3800 Bq/l. The increase in groundwater radionuclides concentrations is associated with the reduced sorption properties of local sediments, which affect the migration capacity of radionuclides in the environment. The decrease of the 90Sr sorption properties of sediments is caused by changes in the chemical composition of groundwater. A new statistical method has been performed. Method based on the Monte Carlo method in order to evaluate the correlations between the 90Sr volumetric activity and the groundwater chemical composition components. Simulation results using this method suggest a correlation between the volumetric activity of 90Sr, the concentrations cations, the pH, and the oxidation index (organic contents). A direct correlation was established between the volumetric activity of 90Sr, Ca2+ concentrations and the pH of groundwater in the range from 7 to 12.4. It was revealed that the concentrations of Na+ and K+ do not affect the conditions of 90Sr migration with groundwater. There is an inverse correlation between the concentration of 90Sr and the oxidation index, which is an indirect indicator of the organic substances content in water. Thus, the presence of organic substances in the groundwater effectively promotes sorption of 90Sr. The proposed method of geochemical statistics enables a quantitative assessment of groundwater monitoring results.

Influence of the Nb content and microstructure of sitinakite-type crystalline silicotitanates (CSTs) on their Sr2+ and Cs+ sorption properties

Radioactive wastewater contaminated with 137Cs and 90Sr are produced at different stages of the nuclear fuel cycle. Transferring these radionuclides to a stable solid matrix is crucial for safe wastewater management and long-term storage. Sitinakite Crystalline silicotitanates (CSTs) are among the most selective mineral ion exchangers for Cs and/or Sr depending on the pH of the medium and the CST chemical composition (Nb doping). To better understand how their microstructure affects their sorption properties, CSTs with different morphologies (consisting of submicronic to micronic particles) and Nb contents (from 0% to 25%) were synthesized and characterized in terms of their Sr2+ and Cs+ sorption properties at moderately basic pH. The Sr2+/Na+ and Cs+/Na+ equilibrium exchange diagrams obtained highlight the presence of two kind of sorption sites with different selectivities and sorption capacities. The first, kind of site, highly selective for Sr and less selective for Cs at moderately basic pH, was attributed to “tunnel” sites in the CST structure. The second one, less selective for Sr and Cs, seems to be a surface site. Although Nb doping was found to promote Cs sorption and hinder Sr sorption at moderately alkaline pH, the accessibility and selectivity of these two sites was found to depend more strongly on the microstructure of the CSTs. Results indicate that the more highly crystalline, micronic particles, with fewer structural defects, are more selective for Sr, but that the larger specific surface areas (greater number of surface sites) afforded by the submicronic particles are associated with larger sorption capacities.

Preparation and characterization of ZnO/Chitosan nanocomposite for Cs(I) and Sr(II) sorption from aqueous solutions

Preparation and characterization of ZnO/Chitosan nanocomposite for Cs(I) and Sr(II) sorption from aqueous solutions