Sorption Of Strontium Research Articles

Selective sorption of strontium using two different types of nanostructured manganese oxides

The aim of this study was to investigate the sorption properties of two different types of nanostructured manganese oxide materials for radioactive species such as strontium and cesium. Two different nanostructured manganese oxides were prepared using either hydrothermal and reduction methods. Manganese oxide nanowires were synthesized by the hydrothermal method followed by heat treatment. Nanostructured microspheres of manganese oxide were synthesized by reduction of MnO4 − with hydrochloric acid. Both the synthetic manganese oxides were characterized by powder X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller specific surface area measurements. In order to examine the sorption characteristics of both the nanostructured manganese oxides, batch isotherm tests were carried out. The results showed that manganese oxide nanowires exhibited high affinity for strontium. The sorption capacity of manganese oxide nanowires for strontium was 124.0 mg/g (ca. 2.83 meq/g). The kinetics of strontium sorption by the two nanostructured manganese oxides were found to match well with pseudo-second-order rate model. Rapid removal of strontium by both the nanostructured manganese oxides occurred at initial stage of the sorption process. This result implies that the sorption mechanism of strontium is likely due to ion exchange and/or chemisorption. Based on these results, the manganese oxide nanowires could be an excellent sorbent or ion exchanger for the removal of radioactive strontium from nuclear waste water, surface water and groundwater.

Clay-salt slimes of the JSC \u201cBelaruskali\u201d as potential engineering barriers in the radioactive waste repositories: sorption of Cs(I), Sr(II), Eu(III) and Am(III)

Results of sorption of caesium(I), strontium(II), europium(III) and americium(III) ions on the aluminosilicates separated from the clay-salt slimes (CSS) depending on the contact time, pH, initial metal concentration are presented. CSS 1A and CSS 1B sorbents appear to be sufficiently chemically and radiation stable for practical application in treatment of the radioactive wastewaters.

Sorption isotherms of metal ions onto an N-(2-sulfoethyl)chitosan-based material from single- and multi-component solutions

ABSTRACTThe scope of work is to study the mutual influence of metal ions during their sorption by sulfoethylated chitosan. The sorption isotherms of metal ions from single- and multi-component solutions are obtained. The sorption capacity of the sorbent towards Ag(I) and Cu(II) is revealed to be 1.63 and 1.41 mmol/g in single-, and 1.40 and 0.85 mmol/g in five-component solution. By comparing the affinity parameter and capacity of sulfoethylated chitosan towards ions in single- and multi-component solutions, it is concluded that Ag(I) and Cu(II) ions suppress the sorption of cobalt(II), nickel(II), zinc(II), cadmium(II), magnesium(II), calcium(II), strontium(II), barium(II), manganese(II) and lead(II).

Biosorption of strontium(II) from aqueous solutions by Bacillus cereus isolated from strontium hyperaccumulator Andropogon gayanus

Abstract The biosorption of strontium(II) from aqueous solutions using dead bacteria biomass was investigated in this study. Phylogenetic analysis based on 16S rDNA sequence demonstrates that the isolated strain belonged to Bacillus cereus . The bacteria exhibited the highest strontium sorption capacity at an initial pH of 5.0, contact time of 50 min, biomass dosage of 3.0 g L −1 and agitation speed of 120 rpm. The adsorption profile was better matched by Langmuir than Freundlich model. The maximum biosorption capacity obtained by Langmuir model was 58.79 mg g −1 . Adsorption kinetics indicate that the pseudo-second order model was appropriate to describe the biosorption process. Fourier transform infrared (FT-IR) spectroscopy analysis indicates that the main functional groups responsible for biosorption of strontium(II) were hydroxyl, carboxyl and amino. The isolated bacteria B. cereus can be a great potential biosorbent to remove strontium ions from aqueous solutions.

Non-Fickian dispersive transport of strontium in laboratory-scale columns: Modelling and evaluation

In the context of environmental remediation of contaminated sites and safety assessment of nuclear waste disposal in the near-surface zone, we investigate the leaching and non-Fickian dispersive migration with sorption of strontium (mocking strontium-90) through columns packed with sand and clay. Analysis is based on breakthrough curves (BTCs) from column experiments, which simulated rainfall infiltration and source term release scenario, rather than applying constant tracer solution at the inlet as commonly used. BTCs are re-evaluated and transport parameters are estimated by inverse modelling using two approaches: (1) equilibrium advection-dispersion equation (ADE); and (2) continuous time random walk (CTRW). Firstly, based on a method for calculating leach concentration, the inlet condition with an exponential decay input is identified. Secondly, the results show that approximately 39%–58% of Br− and 16%–49% of Sr2+ are eluted from the columns at the end of the breakthrough experiments. This suggests that trapping mechanisms, including diffusion into immobile zones and attachment of tracer on mineral surfaces, are more pronounced for Sr2+ than for Br−. Thirdly, we demonstrate robustness of CTRW-based truncated power-law (TPL) model in capturing non-Fickian reactive transport with 0<β<2, and Fickian transport with β>2. The non-Fickian dispersion observed experimentally is explained by variations of local flow field from preferential flow paths due to physical heterogeneities. Particularly, the additional sorption process of strontium on clay minerals contributes to the delay of the peak concentration and the tailing features, which leads to an enhanced non-Fickian transport for strontium. Finally, the ADE and CTRW approaches to environmental modelling are evaluated. It is shown that CTRW with a sorption term can describe non-Fickian dispersive transport of strontium at laboratory scale by identifying appropriate parameters, while the traditional ADE with a retardation factor fails to reproduce the complex non-Fickian transport of strontium with strong sorption on clay surface.

An assessment of strontium sorption onto bentonite buffer material in waste repository.

In the present study, changes occurring in sorption characteristics of a representative bentonite (WIn-BT) exposed to SrCl2 (0.001-0.1M) under the pH range of 1-13 were investigated. Such interaction revealed a significant variation in surface charge density and binding energy of ions with respect to bentonite, and alteration in their physicochemical properties viz., specific surface area, cation exchange capacity, thermal and mechanical behaviour were observed. The distribution coefficients (k d) calculated for sorption onto virgin (UCBT) and contaminated bentonite (CBT) indicated a greater influence of mineralogical changes occurred with variance of pH and strontium concentration. Notably, the sorption mechanism clearly elucidates the effect of structural negative charge and existence of anionic metal species onto CBT, and depicted the reason behind significant k d values at highly acidic and alkaline pH. The maximum k d of UCBT and CBT(0.001M SrCl2) were 8.99 and 2.92L/kg, respectively, at the soil pH 8.5; whereas it was 2.37 and 1.23L/kg at pH 1 for the CBT(0.1M SrCl2) and CBT(0.01M SrCl2), respectively. The findings of this study can be useful to identify the physicochemical parameters of candidate buffer material and sorption reversibility in waste repository.

Sorption of cesium and strontium radionuclides onto crystalline alkali metal titanosilicates

Sorption of tracer amounts of 137Cs and 90Sr radionuclides from model solutions of various compositions onto synthetic titanosilicates, framework ivanyukite and layered SL3, both synthesized at the Center for Nanomaterials Science, Kola Scientific Center, Russian Academy of Sciences, was studied. Synthetic ivanyukite and titanosilicate SL3 well compete with Termoxid-25 ferrocyanide sorbent in the ability to take up cesium from neutral NaNO3 solutions and from a simulated solution of bottom residue from a nuclear power plant with RBMK reactors. The maximal sorption of 137Cs onto ivanyukite is observed at pH 6–7. The dependence of the 137Cs distribution coefficient (K d) on ivanyukite on the concentration of sodium and potassium ions in the solution was studied. Potassium ions affect the cesium sorption more strongly than sodium ions do. In the ability to take up 90Sr, synthetic ivanyukite well competes with synthetic zeolite of type A and with the sorbent based on modified manganese dioxide. The dependences of K d of 90Sr on the concentrations of the Na+ and Ca2+ ions in the solution were determined. Calcium ions affect the strontium sorption more strongly than sodium ions do. Ivanyukite and SL3 show promise as sorbents for removing cesium and strontium radionuclides from multicomponent salt solutions.

Application of response surface methodology (RSM) for optimization of strontium sorption by synthetic PPy/perlite nanocomposite

Application of response surface methodology (RSM) for optimization of strontium sorption by synthetic PPy/perlite nanocomposite

Comparison the sorption properties of clinoptilolite and synthetic zeolite during sorption strontium from the water solutions in static conditions: Sorption and quantitative determination of strontium by the method PIXE

The comparison strontium sorption from water solutions by the clinoptilolite and synthetic zeolites have made. The time of sorption equilibrium occurrence in the liquid-zeolite system has been determined for strontium. The sorption coefficient (Ks) of strontium for the zeolite NaX reached 91.0% and 90.6% for the zeolite NaA. The sorption coefficient (Ks) of strontium for clinoptilolite amounted to 88.5%. Studies were made into the impact of strontium concentration in water on the sorption processes. It is found that a three-fold increase of strontium concentration in the solution leads to a 20.0% reduction in the sorption coefficient. Zeolite use recommendations are proposed for strontium sorption at industrial conditions. The methods have been developed for quantitative determination of strontium in the carbon matrix by using proton-induced X-ray emission (PIXE). A beam of 1.6MeV protons was used to excite the target. The workability of carbon targets analyzable at nuclear-physical complexes of energy 1.6MeV was investigated. The targets resistance under a multiple exposure to the proton beam was determined, that being displayed in the persistence of the specific yield of X-ray emission K-shell of strontium. A linear regularity in the intensity variation of the K-radiation of strontium as a function of spectrum measurement wiht time increase was determined. The linear relationship between the quantitative content of strontium and its X-ray emission K-shell was obtained. This method allows to determine small quantities of strontium by 0.0007mg.

Sorption of strontium by sorbents on the base of di-(tert-butylcyclohexano)-18-crown-6 with use of various diluents

Set of sorbents were obtained on the base of di-(tert-butylcyclohexano)-18-crown-6, various diluents and styrene–divinylbenzene support for strontium sorption from nitric acid solutions. First it was proposed to use nitrobenzene and 1,1,7-trihydrododecafluoroheptanol as diluents in obtaining sorbents on the base of crown ethers, it was shown higher efficiency of these diluents in comparison with 1-octanol. The effect of method of support pretreatment, a concentration of crown ether in a sorbent and nitric acid in solution on strontium sorption were examined.

Study of 85 Sr transport through a column filled with crushed granite in the presence of bentonite colloids

Abstract The present work is focused on the study of strontium transport through crushed granite in the presence of bentonite colloids under dynamic arrangement. The aim of the experiments was to investigate the effect of bentonite colloids on strontium migration in crushed granite. The tracer behaviour was studied in a column set-up under aerobic conditions with a continuous inlet of the liquid phase of a constant tracer concentration (activity) and flow rate. Defined volumes of liquid phase were sampled at periodic time intervals at the column outlet for the measurements of tracer concentrations (activity). The transport was described by breakthrough curves. The stepwise approach included these steps: (1) an evaluation of the hydrodynamic column properties by the non-sorbing tracer 3 H; (2) a column experiment with bentonite colloids in deionized water was performed; (3) migration of 85 Sr solution in two liquid phases (deionized and synthetic granitic water); and (4) the transport of a radiocolloid suspension in deionized water was studied. Results showed different behaviour of bentonite colloids and strontium in the column. Bentonite colloids behaved as a non-sorbing tracer: conversely, strontium showed strong sorption on granitic material. The strontium transport in the presence of bentonite colloids differed from strontium transport itself. The strontium transport in the presence of colloids was faster than transport without the bentonite colloids. The observed retention of strontium on granite suggests a higher affinity of strontium towards granitic rock than towards bentonite colloids, and showed the reversibility of the sorption of strontium on bentonite colloids.

Application of sorption-reagent materials in the technology of liquid radioactive waste treatment

Some examples of sorption-reagent materials and variants of their application in the practice of treating liquid radioactive waste have been considered. The data on the strontium sorption on samples of a sorption-reagent material under dynamic conditions at different degrees of dilution and different concentrations of seawater have been presented. These data demonstrate that the most efficient practical applications of sorption-reagent materials consist of decontaminating of seawater concentrates of strontium radionuclides. This task is stated during treatment of liquid radioactive waste (LRW) streams at the Fukushima-1 NPP (Japan), where reverse osmosis concentrates constitute the main problem of localization of the aftermath of the disaster that occurred in 2011.

Simulation of strontium sorption onto rocks at high concentrations of sodium nitrate in the solution

Geochemical simulation of strontium sorption was considered within the framework of studying the radionuclide geomigration. A chemical model describing the interaction in the solution–surrounding rock system under the experimental conditions was constructed on the basis of the experimental data. The influence of the geochemical simulation detailedness on the calculation results was evaluated in numerical experiments performed using the GeRa code developed by the authors. Three sorption models were used: traditional model of linear sorption with the tabulated value of Kd; new model with variable Kd, measured experimentally and functionally depending on the NaNO3 concentration; model with direct calculation of chemical interactions, in which the sorption is considered within the framework of the ion-exchange model.

Influence of pH, competing ions, and salinity on the sorption of strontium and cobalt onto biogenic hydroxyapatite.

Anthropogenic radionuclides contaminate a range of environments as a result of nuclear activities, for example, leakage from waste storage tanks/ponds (e.g. Hanford, USA or Sellafield sites, UK) or as a result of large scale nuclear accidents (e.g. Chernobyl, Ukraine or Fukushima, Japan). One of the most widely applied remediation techniques for contaminated waters is the use of sorbent materials (e.g. zeolites and apatites). However, a key problem at nuclear contaminated sites is the remediation of radionuclides from complex chemical environments. In this study, biogenic hydroxyapatite (BHAP) produced by Serratia sp. bacteria was investigated for its potential to remediate surrogate radionuclides (Sr2+ and Co2+) from environmentally relevant waters by varying pH, salinity and the type and concentration of cations present. The sorption capacity of the BHAP for both Sr2+ and Co2+ was higher than for a synthetically produced hydroxyapatite (HAP) in the solutions tested. BHAP also compared favorably against a natural zeolite (as used in industrial decontamination) for Sr2+ and Co2+ uptake from saline waters. Results confirm that hydroxyapatite minerals of high surface area and amorphous calcium phosphate content, typical for biogenic sources, are suitable restoration or reactive barrier materials for the remediation of complex contaminated environments or wastewaters.

Removal of Strontium Ions by Synthetic Nano Sodalite Zeolite from Aqueous Solution

In this research, the zeolite sodalite, as an inorganic ion exchange material, was chemically produced in the template-free synthesis and evaluated in order to facilitate the sorption of strontium ions from aqueous solutions in batch operations onto acid treated zeolite with dilute H2SO4 solutions. The following indicates what the batch experiments included: a sorbent amount of 0.25 g in 100 mL of strontium solution (50 mg/L), a contact time of 80 min, pH 6 and a 20 oC temperature. To study the kinetics of removal process, three equations, i.e. Morris–Weber, Lagergren (pseudo first order) and pseudo second order were used. The sorption data were applied to the Langmuir, Freundlich, Dubnin-Randkovich (D-R) and Temkin models in order to estimate the sorption capacity, intensity and energy. An evaluation of the thermodynamic parameters ΔH, ΔS and ΔG was done. It was found out from thermodynamic parameters that the sorption of strontium onto zeolite was feasible, spontaneous and endothermic under studied conditions.

The Influence of Soil Fungi on the Sorption of Cesium and Strontium in the Soil Organic Layer

The Influence of Soil Fungi on the Sorption of Cesium and Strontium in the Soil Organic Layer

Kinetics and thermodynamics studies of cobalt, strontium and caesium sorption on marble from aqueous solution

ABSTRACT Adsorption onto solid phases plays an important role in the transport of radionuclides and contaminants in the environment. Radionuclides in radioactive waste have been considered to be hazardous pollutants, and their migration with groundwater is strongly affected by sorption on the geologic media. Therefore, the knowledge of radionuclide sorption is of great importance in the management of radioactive wastes. A series of batch sorption experiments were conducted separately to investigate sorption and transport behaviour of cobalt, strontium and caesium on and through marble. Batch-mode kinetic and equilibrium studies have been carried out at different temperatures. Sorption experimental data were analysed by kinetic and isotherm models. Based on the results obtained, it can be concluded that the marble is an economic and efficient retaining material for environmental hazardous migration and/or leakage of some radionuclides. Therefore, this study could be used as a starting point to establish and consider that rock as a reactive barrier around the disposal facilities at the nuclear activity centres.

Migration and sorption of strontium in clay-sand mixtures

The migration and sorption of Sr in clay-sand mixture were investigated by batch experiment, column experiments and numerical simulation. The results showed that as the clay content in clay-sand mixture increased, the effective porosity, absorption capacity and retardation factor of the mixture for Sr increased, but the dispersion coefficient and migration velocity decreased. The migration of Sr was influenced strongly when clay content was in range of 0–25 %, but influenced weakly when clay content was more than 25 %. The experimental data was consistent with the calculated results by CXTFIT program.

Mechanism of strontium sorption by the mixed nickel–potassium ferrocyanide based on hydrated titanium dioxide

The influence of surface modification of hydrated titanium dioxide (HTD) by mixed nickel–potassium ferrocyanide (NPF) phase on its selectivity for strontium and mechanism of strontium sorption was studied. It was shown that NPF-HTD sorbent possesses the same selectivity for strontium as the HTD sorbent, but higher static exchange capacity (SEC). The Henry distribution coefficient of strontium from a tap water with pH 7.8 ± 0.1 was 10(3.0 ± 0.3) L kg−1; the SEC, calculated according to Langmuir’s isotherm, was 140 mg g−1. Kinetic studies have shown that strontium sorption is limited by both internal and external diffusion as well as by the rate of chemical transformation of the NPF-HTD sorbent.

Evaluation study of cobalt(II) and strontium(II) sorption–desorption behavior for selection of soil remediation technology

Sorption–desorption properties of cobalt(II) and strontium(II) ions were studied using a soil sample from the vicinity of the Serbian radioactive waste processing and interim storage facilities. The mobility of the cations in the soil was evaluated and compared with the intention to facilitate the selection of optimal remediation strategy in case of accidental soil contamination with radioactive cobalt-60 and strontium-90 isotopes. A systematic sorption study was performed through a series of batch experiments at different aging times, cation concentrations and pH. Kinetics experiments revealed that sorbed amounts of cobalt(II) continuously increased with contact time until quasi-equilibrium was reached, while initial fast strontium(II) sorption was followed by a desorption step. Based on the shapes of the sorption isotherms and calculated sorption parameters, it was concluded that cobalt(II) sorbed more selectively and strongly than strontium(II). Sequential extraction showed that, regardless of the initial content of contaminants in the soil and the aging time, high amounts of both cations were bonded to relatively mobile fractions: strontium(II) in the exchangeable, while cobalt(II) in the carbonate and ferromanganese oxide fraction. Strontium(II) was readily desorbed in acidic, calcium(II) and ethylenediaminetetraacetic acid-containing media, whereas complexing agents such as citric and tartaric acids at low pH were more effective reagents for cobalt(II) desorption. The results from the present study indicate that chemical extraction can be considered as remediation option for strontium(II)- and cobalt(II)-contaminated soil.