Sorption Of Cesium Research Articles

Regularities of cesium sorption by fibrous sorbents based on transition metal ferrocyanides

Regularities of cesium sorption by fibrous sorbents based on transition metal ferrocyanides

Correlating shale geochemistry with metal sorption: influence of kaolinite content

ABSTRACT Argillaceous rocks constituting clay fractions are potential host rock candidates for isolation of radioactive waste in underground repositories. The present study aims at characterization of two argillaceous rocks (shales) from different geological settings (surface and subsurface localities) and investigation of their cesium (Cs) sorption behaviour. The shales were characterized using various analytical techniques to evaluate the textural attributes, mineralogical constituents and surface properties. The major mineralogical constituent of the surface and subsurface shale was quartz (62%) and kaolinite (56%), respectively. The abundance of smectite and illite in both the shales was comparable. Fluorescence and UV-Vis spectra confirmed the presence of polyaromatic hydrocarbons (PAHs) in the subsurface shale. The subsurface shale demonstrated higher Cs retention (17 mg g−1) than the surface shale (12 mg g−1) due to higher kaolinite content. Surface analysis of the shale samples revealed involvement of ion exchange mechanism in Cs uptake. The agreement of experimental results with Freundlich sorption isotherm suggests the heterogenous nature of the shales with multiple sorption sites. The correlation of geochemistry (especially the kaolinite content) for both the shales with Cs sorption is clearly highlighted in the present studies. The present investigation implies the applicability of the studied shales for waste management applications.

Insight to the cesium entrapment by natural shale: implications to geological disposal of nuclear waste

ABSTRACT The knowledge of radionuclides sorption behavior of various site-specific heterogeneous geosystems is essential for developing different clean-up strategies and predicting the radiological risks for long term. The present study is aimed at understanding the mineralogical and textural characteristics of natural shale rock (sampled from Kachchh Basin of Gujarat, India) and its correlation with cesium (Cs) sorption behavior. The modal mineralogical composition, textural attributes, petrophysical properties, surface functionalities and morphology of shale were evaluated. Clay minerals (smectite, kaolinite and illite) constitute more than 40% of the shale along with the major component- quartz. A comprehensive Cs batch sorption study performed at varying experimental parameters demonstrated that the maximum Cs retention of shale was 34.80 ± 2.85 mg g−1 in the studied concentration range. Sorption equilibrium data agreed well with Freundlich isotherm, highlighting the heterogeneity of shale. Variation in solution pH (in the range of 6–10) during sorption demonstrated the buffering of solution in near neutral range indicating the role of cations (available in the interlayers of clay minerals) in Cs uptake. Alternatively, the presence of illite mineral in the shale with known frayed edge sites contributed to the irreversibility of sorption event. The present studies illustrate the potential of shale as host rock for its application in nuclear waste management.

The Effect of High-Energy Ball Milling of Montmorillonite for Adsorptive Removal of Cesium, Strontium, and Uranium Ions from Aqueous Solution

Clay minerals are widely used to treat groundwater and surface water containing radionuclides. In our study, the method of mechanochemical activation for increasing the sorption capacity of the natural clay mineral montmorillonite was used. By adjusting the grinding time, the increasing sorption parameters of mechanochemically activated montmorillonite were determined. X-ray diffraction method, scanning electron microscopy, and the determination of the specific surface by low-temperature adsorption–desorption of nitrogen to characterize the natural and mechanochemical-activated montmorillonites were used. It was established that the maximal sorption of uranium, strontium, and cesium is found for montmorillonite after mechanochemical treatment for 2 h. It is shown that the filling of the surface of montmorillonite with ions of different natures occurs in various ways during different times of mechanochemical treatment. The appropriateness of the Langmuir and Freundlich models for the sorption parameters of uranium, strontium, and cesium ions on montmorillonite after its mechanochemical activation was established. The effect of natural organic substances—humic acids—on the efficiency of water purification from uranium on mechanoactivated montmorillonite was studied. The obtained sorbents can be effectively used for the removal of trace amounts of radionuclides of different chemical natures (uranium, cesium, and strontium) from polluted surface and ground waters.

New insights into the mechanism of cesium sorption on titanium hexacyanoferrate: Experimental findings and model development

This study aimed to provide new insights into the mechanism of Cs+ sorption on titanium hexacyanoferrate (Ti–Fe PBA) focusing on the influence of the structure and vacancies. Ti–Fe PBA was synthesized with specific vacancies using a coprecipitation synthesis method. The study successfully demonstrated the unique structure of Ti–Fe PBA and determined the ratio of vacancies within its framework through various characterization techniques, including X-ray diffraction, Fourier transform-infrared spectrometry, thermogravimetry, scanning electron microscopy, X-ray photoelectron spectroscopy and sodium hydroxide titration. The synthesized Ti–Fe PBA exhibited an impressive Cs+ sorption capacity of 3.53 mmol g−1 and demonstrated high selectivity, with a Kd value 1.5 × 106 for Cs+ sorption. In addition, Ti–Fe PBA displayed excellent stability, rapid uptake kinetics and maintained high selectivity, even in the presence of high concentrations of coexisting ions. Moreover, our new findings revealed that K–Cs ion exchange specifically occurring at the interstitial sites within the framework structure accounted for ∼35 % of the total Cs+ sorption. A sorption-surface complexation model utilizing a coupling technique that integrated PHREEQC with Python enabled in-depth analysis of titration, pH effects and sorption isotherms. The modelling results revealed that the strong ion exchange sites ≡SsOH and ≡SsONa on surfaces and vacancies contributed ∼65 % of the total Cs+ sorption.

Nanofiltration Purification of Liquid Radioactive Waste

The paper presents the results of testing the purification of real liquid radioactive waste from radionuclides, bottom residues of the Kola and Beloyarsk nuclear power plants (NPP), as well as low-level wastewater from the radiochemical building of the Institute of Physical Chemistry and Electrochemistry RAS (IPCE RAS) using the method of nanofiltration (NF) using a polymer membrane manufactured by the Russian company “RM Nanotech.” It has been shown that in the case of single-stage NF purification of bottoms of the Kola NPP, the coefficient of purification from 60Co is 2.8, while no purification from 137Cs practically occurs. When cleaning the bottom residues of the Beloyarsk NPP from 60Co using a five-stage scheme, a coefficient of purification from 60Co equal to 388 was obtained. The combination of nanofiltration purification and selective sorption of cesium on the ferrocyanide sorbent Temoksid-35 makes it possible to obtain a dry salt residue that is not related to radioactive waste. When using the method of nanofiltration for the treatment of low-level wastewater of the Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, the degree of purification was, %: 137Сs ~ 75; 90Sr ~ 91; 241Am ~ 99.5; 152Eu ~ 91; 239Pu ~ 99.5.

Synthesis of Prussian blue-embedded magnetic micro hydrogel for scavenging of cesium from aqueous solutions; Batch and dynamic investigations

A magnetic micro porous structure composite based on alginate and Prussian blue (M-SA-PB) was simply prepared for cesium removal from the aqueous solutions. The gelation and formation of PB proceeded through the same step, which made the PB homogenously distributed and firmly attached to the alginate matrix. The homogenizer was applied to break down the bulky gel structure into micro-ones, and the lyophilizer will provide the porous structure. Batch cesium sorption experiments showed that the adsorption kinetics and isotherms were attributed to the pseudo-second-order model and Langmuir isotherm. Moreover, the Cs-ion is favorably adsorbed on the M-SA-PB composite surface as a monolayer towards Cs, with a maximum adsorption capacity reach of 191.0 mg/g. Furthermore, the M-SA-PB adsorbent showed excellent adsorption selectivity of Cs from multiple-ion solutions. Our work was extended to use the M-SA-PB composite in dynamic cesium sorption. The column studies showed that the removal efficiency of Cs+ increased with increasing bed depth as well as the initial cesium concentration. Finally, as previously mentioned, the M-SA-PB could be considered an excellent Cs+ scavenger employing both batch and dynamic approaches, which makes it a promising adsorbent for practical investigations.

Sorption of cesium from strongly alkaline solutions on a modi ed ferrocyanide sorbent «fersal»

The sorption of cesium from solutions of sodium and potassium nitrates, sodium hydroxide, and also from a model solution simulating alkaline high-level waste (HLW) of FSUE PO «Mayak» on various resorcinolformaldehyde sorbents (RFS), on sorbent based on a boron-containing polymer of the Clevasol brand and on sorbent of the Fersal brand based on modi ed nickel ferrocyanide was studied under batch conditions. It is shown that in all the media studied, the Fersal sorbent has the best sorption-selective characteristics with respect to cesium. During the sorption of cesium from a model solution of HLW under dynamic conditions, the volume of the passed solution to 1% breakthrough for the Fersal sorbent is 127 bed volumes (b.v.). The puri cation resource of the other studied sorbents is 3-4 times less. Desorption of cesium from the Fersal sorbent can be carried out by passing 9-10 b.v. 7.5 mol/dm3 HNO3, however, in this case, the sorbent granules are destroyed, which does not allow it to be reused. It is concluded that the Fersal sorbent is the most promising for the treatment of alkaline HLW.

Sorption of Cesium from Strongly Alkaline Solutions on a Modified Ferrocyanide Sorbent Fersal

Sorption of Cesium from Strongly Alkaline Solutions on a Modified Ferrocyanide Sorbent Fersal

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

137Cs, 85Sr and 60Co sorption from model solutions of low activity liquid radioactive waste by modified oil shale

The results of the study of cesium, strontium, cobalt radionuclides sorption from model solutions simulating liquid radioactive waste on promising sorbents based on thermally modified oil shale are presented. The dependency of texture parameters obtained from the results of nitrogen adsorption-desorption on the treatment method of oil shale and their relationship to sorption parameters such as distribution coefficient and removal efficiency was discussed. Understanding how pore characteristics affect the sorption activity of such complex systems as sorbents is important for the creation of radionuclide sorption materials with improved characteristics. The efficiency of sorption of cesium, strontium and cobalt radionuclides was rather high for sorbent samples: the distribution coefficient was about 103–104 ml/g with a removal efficiency of more than 66 %. The most effective sorbent was obtained from oil shale with a heating rate of 5 deg/min without subsequent steam treatment, which is recommended to be used for low-active radioactive waste treatment.

Effect of Competing Ions on Multisorption (Cs+, Sr2+) by Composite Sorbents Based on Natural and Synthetic Zeolites

In the course of the research, the effect of competing ions (Na+) on multisorption (Cs+, Sr2+) by composite sorbents based on natural and synthetic zeolites under static conditions was studied. It was found that the maximum concentration of competing ions (0.4 g of NaCl per 100 ml of solution) leads to a decrease in cesium sorption by 20%, and strontium sorption decreases by 10%. At the same time, high rates of sorption of cesium and strontium are preserved. Thus, for a composite sorbent (clinoptilolite -30%: zeolite NaX -70%), the sorption of cesium was 67.9%, and the sorption of strontium was 87.6%. The analytical technique was developed on the basis of the PIXE (Proton Induced X-ray Emission) method and made it possible to qualitatively and quantitatively determine the content of isotopes. The work was performed at the analytical nuclear-physical complex "Sokil". The energy range of the electrostatic accelerator is 200-2000 keV. The complex made it possible to carry out all the main methods of analysis using ion beams. The targets were placed in the exit, at the Chamber for PIXE. To carry out measurements, a vacuum with a pressure of 10-4 Pa was created in the chamber. To excite the atoms of cesium, strontium, a proton beam with an energy of Ер≈1400 keV was used. The characteristic X-ray radiation of the L-series of cesium atoms and K-series of strontium atoms was recorded by two detectors: XR-100CR Si-PIN X-Ray and Ge(HP). The sorption coefficient (Sorption, %) was used as a quantitative characteristic of the interaction of sorbents with cesium, strontium.

Nanodispersion of ferrocianides for purification of man-made contaminated water containing caesium

A method of obtaining a nanodispersion of nickel-potassium ferrocyanides intended for purification of man-made polluted waters is proposed. It is applicable to purify effluent and floor drain water at nuclear power plants, which contains caesium, strontium, cobalt, manganese and other transition metals. The optimal conditions for the synthesis of nanodispersion have been determined, which is represented by clusters of nanoparticles associated with water molecules and nitrates dispersed in a dilute solution of nickel and potassium nitrates. On the surface of the formed nanocrystals there are fragments of structures of smaller formations. The mechanism of sorption of ions of alkali, alkaline earth and transition metals is investigated considering the ion charge density. The effect of competing ions (strontium, cobalt, manganese) on the sorption of caesium is taken into account. An integrated method of purification of multi-component man-made solutions including drainage waters of nuclear power plants is based on the use of nanodispersion of nickel-potassium ferrocyanides in combination with bentonite clay, which allows removing caesium from the drainage simulator with an efficiency of 96%, and strontium and transition metal ions (cobalt, manganese, copper, iron) with an efficiency of at least 98%.

Influence of non-equilibrium and nonlinear sorption of 137Cs in soils. Study with stirred flow-through reactor experiments and quantification with a nonlinear equilibrium-kinetic model

This paper addresses the modelling of cesium sorption in non-equilibrium and nonlinear conditions with a two-site model. Compared to the classical Kd approach, the proposed model better reproduced the breakthrough curves observed during continuous-flow stirred tank reactor experiments conducted on two contrasted soils. Fitted parameters suggested contrasted conditions of cesium sorption between 1) equilibrium sites, with low affinity and high sorption capacity comparable to CEC and 2) non-equilibrium sites, with a fast sorption rate (half-time of 0.2–0.3 h), a slow desorption rate (half-time of 3–9 days) and a very low sorption capacity (0.02–0.04% of CEC). Comparison of EK sites densities with sorption capacities derived from the literature suggests that the EK equilibrium and kinetic sites might correspond to ion exchange and surface complexation of soil clay minerals respectively. This work stresses the limits of the Kd model to predict 137Cs sorption in reactive transport conditions and supports an alternative non-equilibrium nonlinear approach.

Effect of calcination temperature on geopolymer for the adsorption of cesium

The effect of calcination on geopolymer for the adsorption of cesium and related change of microstructure were explored. The sorption results indicated that the cesium sorption amounts of geopolymers after calcination dramatically decreased. However, the specific surface areas of accordingly calcined geopolymers increased significantly. Aluminum tetrahedrons are the source of negative charges for the adsorption of cesium. It was found that approximately 10% of tetrahedrally coordinated aluminum was transformed to penta-coordinated aluminum and hexa-coordinated aluminum after thermal treatment. Furthermore, approximately 10% of aluminum on the surface of calcined geopolymers decreased compared to raw geopolymer. Therefore, calcination has a great influence on the cesium sorption due to the decrease of aluminum tetrahedrons on the surface of geopolymer.

Sorption of cesium on surrounding granite of Chinese low- and medium-level nuclear waste repository in the groundwater environment

Sorption of cesium on surrounding granite of Chinese low- and medium-level nuclear waste repository in the groundwater environment

Influence of the Nanotube Morphology and Intercalated Species on the Sorption Properties of Hybrid Layered Vanadium Oxides: Application for Cesium Removal from Aqueous Streams.

The present paper examines the impact that the nanotube morphology and organic or inorganic intercalated species may have on the cesium sorption by layered vanadium oxides prepared with the use of hexadecylamine as a structure-directing agent. The hybrid material represented by a chemical formula of (V2O5)(VO2)1.03(C16H36N)1.46(H2O)x was achieved through accelerated microwave-assisted synthesis carefully optimized to ensure the best compromise between the scroll-like morphology and the hydrophobic character. To enhance its dispersibility in water, this sample was subsequently modified by progressive replacement of the C16H36N+ units by NH4+ cations. The final materials represented a stacking of lamellar sheets with a worse scroll-like morphology. Both the optimization procedure and the template removal were monitored on the basis of scanning and transmission electronic microscopy, X-ray diffraction, infra-red spectroscopy, inductively coupled plasma-optical emission spectrometry, X-ray photoelectron spectroscopy, and elemental analysis, supplemented by adequate simulations methods providing the reference IR spectra and XRD patterns for comparison or the textural parameters of the samples. The comparison of the cesium sorption from either a 4:1 ethanol–water mixture or aqueous solutions pointed toward the solubility of intercalated cations in the bulk solution as the main factor limiting their displacement from the interlayer space by the oncoming cesium ones. The sample obtained after 70% exchange with NH4+ exhibited a maximum sorption capacity of 1.4 mmol g−1 from CsNO3 aqueous solutions and its retention efficiency remained significant from low-concentration Cs solutions in river or sea water.

The sorption of caesium to glauconite sands obeys local equilibrium at environmentally relevant water flow rates

Glauconite has a radiocaesium interception potential that is comparable to illite, suggesting that glauconite containing sands may be an effective geological barrier for radiocaesium. However, glauconite is present as coarse pellets (∼0.5 mm diameter) and considerable sorption non-equilibrium may occur during reactive transport in these permeable sands. Here, we analysed trace caesium (Cs) sorption kinetics in agitated batch suspensions to predict reactive transport at variable flow rates in glauconite containing sands. Batch sorption experiments showed that Cs+ sorption KD values in agitated suspension of glauconite sand of the Diest Fm (Dessel Member) increased by a factor 6 to 8 between 48 h and 94 days at trace Cs+ concentration (∼10−9 M). A breakthrough (BT) experiment was set up with 13 packed columns of the same Fm that were leached with 10−6 M Cs+ at variable flow rates equivalent to water residence times 0.07–3.4 days for a duration of 154 days. The BT was observed in treatments with the higher flow rates after 890–1170 pore volumes. The breakthrough expressed in pore volumes revealed earlier breakthrough at only the highest flow rate, indicating chemical non-equilibrium in that treatment. The BT curves were modelled with HP1 (Hydrus-PhreeqC), thereby relying on batch data obtained at 90 days and assuming local reaction equilibrium. The BT curves were well predicted with this model, corroborating local equilibrium except at the highest flow rates. It is concluded that Cs+ sorption on highly permeable glauconite sands is sufficiently fast to delay breakthrough with flow rates below 2.4 m d−1. Only in high flow rate, unrealistic for the Neogene and Paleogene formations, early breakthrough could occur.

Sorption of Cesium and Strontium Radionuclides by Synthetic Ivanyukite from Model and Process Solutions

Sorption of Cesium and Strontium Radionuclides by Synthetic Ivanyukite from Model and Process Solutions