Cesium Desorption Research Articles

Kapok fiber composites minimizing secondary waste and disposal costs for large-scale radioactive liquid treatment

Conventional liquid treatments for large-scale, low-level radioactive wastewater, such as ion exchange and waste solidification, face challenges due to the large amounts of secondary waste and high disposal costs. A new large-scale decontamination method is proposed that uses kapok fiber composites for rapid radionuclide adsorption and high volume reduction to minimize secondary waste. The composite consists of natural zeolite and kapok holocellulose, which has high water-soaking ability and low-temperature pyrolysis. The kapok composites, fabricated using a commercial wet-laid nonwoven manufacturing process, absorbs 99% of low-level radioactive cesium in 20 min, reducing the volume by 98% and the weight by 47% at 300 °C. The low-temperature pyrolysis process below 300 °C prevents cesium desorption and gasification by avoiding zeolite destruction. The mass-producible kapok composites can be used for adsorbing various radionuclides in large-scale wastewater by attaching specific adsorbents for target isotopes to the composites.

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.

Enhanced removal of cesium from hydrobiotite using polyacrylonitrile (PAN)-based nickel ferrocyanide beads

The desorption of cesium (Cs) from contaminated clay minerals remains challenging because of the restricted efficiency of the removal process. Therefore, in the present study, a bead-type adsorbent was added during the conventional acid washing process to improve the removal of Cs+ from a clay mineral. As the Cs+ adsorbent, polyacrylonitrile-based nickel potassium hexacyanoferrate (NiFC-PAN) was used to selectively adsorb Cs+ in a strongly acidic solution containing competing ions. To prevent erosion of the adsorbent under harsh environmental conditions and to facilitate the separation of clay particles, PAN was deliberately constructed as large beads. The synthesized adsorbent (NiFC/PAN in a 2:1 ratio) showed high selectivity for Cs+, with a maximum capacity for Cs+ adsorption of 162.78 mg/g in 0.5 M HNO3 solution. Because the NiFC-PAN demonstrated greater Cs+ selectivity than the clay mineral (hydrobiotite, HBT), the addition of NiFC-PAN during the acid washing significantly increased Cs+ desorption (73.3%) by inhibiting the re-adsorption of Cs+ on the HBT. The radioactivity of 137Cs-HBT was substantially decreased from 209 to 27 Bq/g by the acid treatment in the presence of NiFC-PAN, corresponding to a desorption efficiency of 87.1%. Therefore, these results suggest that the proposed technique is a potentially useful and effective method for decontamination of radioactive clay.

Influence of head group structure of cationic surfactants on the desorption of cesium from clays and clay minerals

The role of cationic surfactants head group for cesium (Cs) desorption from clays and clay minerals was investigated in this study by using two surfactants having similar hydrocarbon chain lengths but different head group types. Two surfactants used were dodecyltrimethylammonium bromide (DTAB) with linear structure and benzyldodecyldimethylammonium bromide (BDAB) containing bulkier head group. The results indicated that Cs desorption from bentonites using both surfactants was accompanied by interlayer expansion. In the case of Na-bentonite, BDAB showed higher Cs desorption efficiency than DTAB due to larger interlayer expansion after intercalation of BDAB. In contrast, the amount of desorbed Cs from Ca-bentonite was comparable, corresponding to the almost identical interlayer expansion after intercalation of both surfactants. It was because Ca ions present in Ca-bentonite must associate with two negatively charged interlayers, hence limiting its expansion. Cs desorption from kaolinite was more governed by surfactant micelles. When the surfactant micelles were formed earlier at low concentration, considerable desorption of Cs was achieved. In this regard, BDAB more efficiently desorbed Cs compared to DTAB owing to rapid formation of BDAB micelles at lower concentrations caused by the increase in head group size. For Cs desorption from illite, both surfactants even exhibited similar insignificant results with HCl used as a control of desorbent. Frayed edge sites in illite probably provoked strong Cs retention causing the difficulty in desorbing Cs. Furthermore, desorption kinetic data of Cs from all samples using both surfactants fitted well with pseudo-second order model, suggesting the occurrence of chemical desorption by involving ion-exchange mechanism.

Evaluation of DGT and DGT-PROFS modeling approach to estimate desorption kinetics of Cs in soils

The aim of this paper is to assess the suitability of DGT to extract kinetic rates of desorption of cesium (Cs) from soils. For this purpose, laboratory experiments with a natural soil spiked with Cs were carried out under three different contamination conditions, reflecting either an increase in Cs contamination level or an ageing of the contamination within the soil. The experimental results, i.e. the Cs accumulation kinetics onto DGT probes were interpreted by the DGT-PROFS model. The latter calculates the partitioning of Cs between two particulate pools, describing weak and strong interactions respectively, as well as kinetic rates describing exchange reactions. Experimental conditions did not show any major impact on desorption rates, suggesting that desorption kinetics were not significantly affected by contamination level and ageing. Instead, the distribution of Cs among weak and strong sites was shown to be the predominant factor governing the differences observed in the remobilization of Cs to porewater among experimental conditions. The DGT technique combined with the DGT-PROFS modelling approach was proved to be efficient in estimating desorption kinetic rates of Cs in soils.

Behaviors of Desorption Agents During Removal of Cs From Clay Minerals and Actual Soil

The behaviors of various desorption agents were investigated during the desorption of cesium (Cs) from samples of clay minerals and actual soil. Results showed that polymeric cation exchange agents (polyethyleneimine (PEI)) efficiently desorbed Cs from expandable montmorillonite, whereas acidic desorption solutions containing HCl or PEI removed considerable Cs from hydrobiotite. However, most desorption agents could desorb only 54% of Cs from illite because of Cs’s specific adsorption to selective adsorption sites. Cs desorption from an actual soil sample containing Cs-selective clay mineral illite ( PEI > NH4+, and the highest Cs desorption amount achieved using HCl was 83%. Unlike other desorption agents with only cation exchange capabilities, HCl can attack minerals and induce dissolution of metallic elements. HCl’s ability to both alter minerals and induce H+/Cs+ ion exchange is expected to promote Cs desorption from actual soil samples.

A review on cesium desorption at the freshwater-seawater interface

A review on cesium desorption at the freshwater-seawater interface

Features of Field Desorption of Sodium and Cesium from the Surface of a Carbonized Rhenium Field Emitter

We used field emission microscopy to study the field desorption of sodium and cesium atoms from a rhenium field emitter precarbonized in benzene vapor. The dependences of the ion currents of sodium and cesium on the voltage applied to the field emitter differ. The difference in the ion current dependences is explained by the formation of multilayer graphene on the crystalline surface of a rhenium field emitter in the regions of low-index faces and its intercalation by alkali metal atoms with different ionization potentials and different atomic and ionic radii.

Cs desorption behavior during hydrothermal treatment of illite with oxalic acid

The desorption of radioactive cesium (Cs) in soil is influenced by the clay mineral type, adsorption site, and concentration of Cs. In this study, experiments to detect desorption of non-radioactive and radioactive Cs from illite using oxalic acid were performed for 2days at 70°C in hydrothermal conditions. The results showed that the 133Cs removal efficiency by oxalic acid and inorganic acid treatment was similar at high concentration (22.86mmol/kg) of non-radioactive 133Cs. In the radioactive 137Cs experiment, the removal efficiency by oxalic acid was higher than that by inorganic acid at low concentration (0.79 × 10-6mmol/kg) of radioactive 137Cs. Based on the illite hypothetical frayed edge site (FES) concentration of 0.612mmol/kg, the results suggested that 137Cs was preferentially adsorbed to FES on illite. The 137Cs at low concentrationwas difficult to remove because it was irreversible adsorption to FES, while the non-radioactive Cs at high concentrationwas mainly adsorbed to planar sites, and so was easy to desorb by ion exchange. Based on the results of NMR, FTIR, and XPS analyses, we concluded that the higher efficiency of 137Cs removal at low concentration by oxalic acid treatment than by treatment with inorganic acid was because of chelation effects associated with the complexation of oxalic acid (ligands) and metal ions in irreversible site (FES).

Hydrothermal-treatment desorption of cesium from clay minerals: The roles of organic acids and implications for soil decontamination

The adsorption and desorption of cesium (Cs) on clays of contaminated soil in a rhizosphere zone can be greatly affected by various biogeochemical processes, the timespans of which are usually months to years. Herein, we present several representative scenarios of the binding of Cs on diverse sites of vermiculitized biotite by controlled Cs adsorption to particles of different sizes. We investigated whether and how the fixed Cs in the different scenarios is desorbed by ambient and hydrothermal treatments with several low-molecular-weight organic acids (LMWOAs). The results showed that the sorbed Cs was discriminatively retained in the un-collapsed, partially collapsed, and thoroughly collapsed structures of vermiculites. The desorption of the sorbed Cs by hydrothermal LMWOAs extractions was easily realized in the un-collapsed structure, but was limited or minimal in the partially collapsed and thoroughly collapsed structures. The Cs desorption varied in accord with the LMWOA species applied and increased with the acid concentration, temperature, and number of treating cycles. The analysis of Cs-desorbed specimens confirmed their partial destruction and interlayer expansion, suggesting that the underlying mechanism of Cs removal by LMWOAs involves not only acid dissolution and complexation but also the accelerated weathering of clays within a short time under hydrothermal conditions. Our findings contribute novel insights into the mobility, bioavailability, and fate of Cs in contaminated soils and its removal from these soils for environmental restorations.

Desorption of cesium from hydrobiotite by hydrogen peroxide with divalent cations

In this study, hydrogen peroxide (H2O2) was used to enhance the cation-exchange treatment for Cs+ desorption from clay minerals. Among various investigated clay minerals, hydrobiotite (HBT), which has interstratified layers of vermiculite and biotite, exhibited the highest Cs+ sorption capacity and the most favorable H2O2 activation because of its high Fe content. In X-ray diffraction analysis, HBT treated with H2O2 and 0.1 M Mg2+ showed substantial changes in its basal spacing, indicating expansion of the interlayer region induced by treatment of H2O2 and strongly hydrated divalent cations. In addition, more than 80% of the Cs+ was readily desorbed from HBT with 35% H2O2 solution and 0.1 M Mg2+ at room temperature. After three cycles under the same treatment conditions (35% H2O2 solution and 0.1 M Mg2+), approximately 99% removal of radioactive Cs+ was achieved. These results suggested that H2O2 treatment with solvated Mg2+ enhanced Cs+ desorption from HBT by altering the interlayer region through intercalation of hydrated divalent cations in conjunction with the H2O2 decomposition reaction.

Anomalous Field-Induced Desorption of Cesium from a Quasi-Spherical Surface of a Carbon-Saturated Rhenium Crystal

Investigation of the field-induced desorption of cesium atoms from the surface of rhenium crystal emitter carbon-saturated in benzene vapors showed that, after desorption from the surface, the process continues and there appears a contour of desorption around {10 $$\bar {1}$$ 1} and {1 $$\bar {1}$$ 00} faces that contracts toward the centers of faces with increasing field strength. This previously unreported anomalous behavior of the field-induced desorption is explained by the intercalation of cesium into graphite structures formed on the emitter surface.

Аномальная полевая десорбция цезия с квазисферической поверхности науглероженного кристалла рения

In the study of field desorption of cesium from rhenium carburized in benzene vapors, it was found that after desorption of cesium from the surface, desorption continues and a desorption contour is formed around the faces (1100), which shrinks to the centers of the faces as the field strength increases. The previously unobserved anomalous behavior of the field desorption is explained using cesium intercalation in graphite structures formed on the surface of the emitter.

Caesium desorption from layer silicate minerals using quaternary ammonium salts

ABSTRACTThe adsorption and desorption of cesium onto layered minerals, zeolite and geochemical reference samples were studied. 0.5 g of bentonite and mica were able to adsorb 71.2 and 51.5 mg of cesium, respectively, from 50 mL of deionized water containing 200 mg/L of cesium under neutral pH condition. These amounts of cesium adsorption were greater than those reported for vermiculites (8.9 and 5.6 mg, respectively). Additionally, the cesium adsorption on mica and vermiculite remained essentially unchanged under seawater conditions, but it decreased drastically on zeolite. The cesium desorption from the layered minerals was promoted by the addition of ammonium ions, namely trioctylmethylammonium chloride and zephiramine. These ammonium ions desorb cesium from the interlayers of the minerals without destroying the mineral structure. The cesium desorption procedure using quaternary ammonium ions would be extremely useful for decontamination of soil containing the layered minerals with adsorbed radioactive cesium.

Evaluation of Ion-Exchange Characteristics of Cesium in Natural Japanese Rocks

A large amount of soil was contaminated by radioactive cesium due to the accident at the Fukushima Daiichi Nuclear Power Plant in Japan in 2011. The adsorption behavior of cesium ions (Cs+) is strongly influenced by numerous factors, including the components, structure and weathering conditions of natural soil. The adsorption and ion exchange characteristics of Cs+ ions onto and from natural Japanese rocks with well-known components were studied. Cs+ adsorption onto volcanic rocks (0.9–5.3 mg/g) occurred more easily than that onto plutonic rocks (0.7–0.8 mg/g) due to differences in crystallinity. In addition, the adsorption quantity of cesium increased with increasing lattice water content and content of ion-exchangeable cations in the rock samples. The cesium adsorption ability of rock was inhibited by seawater and coexisting ions in the solution. Cesium adsorption quantities onto andosol, containing the corrosion products, increased approximately 2.7-fold with increasing pH from neutral to basic. Cesium desorption differed depending on the type of salt used, and the desorption rates were highest with ammonium salts. Cs+ desorption from regions such as the soil interlayer and the pores were inhibited by melting of the rock surface.

Field-Induced Desorption of Cesium from Rhenium

Desorption of cesium atoms from a rhenium point emitter in an electric field has been studied by method of field-desorption microscopy (FDM). Dependence of the desorbing field on degree of emitter surface coverage with Cs atoms is established. The heat of Cs-atom adsorption, which is dependent on the surface concentration of adsorbate and work function of the surface, is estimated in the framework of the model of mirror-image forces for field-induced desorption. Saturation of the rhenium emitter with carbon leads to changes in the character of desorption and in the distribution of desorption zones on the emitter surface.

Desorption of radioactive cesium by seawater from the suspended particles in river water

In 2011, the accident at the Fukushima-Daiichi nuclear power plant dispersed radioactive cesium throughout the environment, contaminating the land, rivers, and sea. Suspended particles containing clay minerals are the transportation medium for radioactive cesium from rivers to the ocean because cesium is strongly adsorbed between the layers of clay minerals, forming inner sphere complexes. In this study, the adsorption and desorption behaviors of radioactive cesium from suspended clay particles in river water have been investigated. The radioactive cesium adsorption and desorption experiments were performed with two kinds of suspended particulate using a batch method with 137Cs tracers. In the cesium adsorption treatment performed before the desorption experiments, simulated river water having a total cesium concentration ([133+137Cs+]total) of 1.3 nM (10−9 mol/L) was used. The desorption experiments were mainly conducted at a solid-to-liquid ratio of 0.17 g/L. The desorption agents were natural seawater collected at 10 km north of the Fukushima-Daiichi nuclear power plant, artificial seawater, solutions of NaCl, KCl, NH4Cl, and 133CsCl, and ultrapure water. The desorption behavior, which depends on the preloaded cesium concentration in the suspended particles, was also investigated. Based on the cesium desorption experiments using suspended particles, which contained about 1000 ng/g loaded cesium, the order of cesium desorption ratios for each desorption agent was determined as 1 M NaCl (80%) > 470 mM NaCl (65%) > 1 M KCl (30%) ≈ seawater (natural seawater and Daigo artificial seawater) > 1 M NH4Cl (20%) > 1 M 133CsCl (15%) ≫ ultrapure water (2%). Moreover, an interesting result was obtained: The desorption ratio in the 470 mM NaCl solution was much higher than that in seawater, even though the Na+ concentrations were identical. These results indicate that the cesium desorption mechanism is not a simple ion exchange reaction but is strongly related to structural changes in the clay minerals in the suspended particles. Hydrated Na+ ions expand the interlayer distance of the clay minerals, resulting in the facile desorption of cesium; in contrast, dehydrated K+ ions reduce the interlayer distance and inhibit the desorption of cesium. In conclusion, the desorption of cesium from the suspended particles is controlled by the presence of sodium and potassium ions and the preloaded cesium concentration in the suspended particles.

Enhanced desorption of cesium from collapsed interlayer regions in vermiculite by hydrothermal treatment with divalent cations

Adsorption of cesium (Cs) on phyllosilicates has been intensively investigated because natural soils have strong ability of immobilizing Cs within clay minerals resulting in difficulty of decontamination. The objectives of present study are to clarify how Cs fixation on vermiculite is influenced by structure change caused by Cs sorption at different loading levels and how Cs desorption is affected by various replacing cations induced at different treating temperature. As a result, more than 80% of Cs was readily desorbed from vermiculite with loading amount of 2% saturated Cs (5.49×10−3mmolg−1) after four cycles of treatment of 0.01M Mg2+/Ca2+ at room temperature, but less than 20% of Cs was desorbed from saturated vermiculite. These distinct desorption patterns were attributed to inhibition of Cs desorption by interlayer collapse of vermiculite, especially at high Cs loadings. In contrast, elevated temperature significantly facilitated divalent cations to efficiently desorb Cs from collapsed regions. After five cycles of treatment at 250°C with 0.01M Mg2+, ∼100% removal of saturated Cs was achieved. X-ray diffraction analysis results suggested that Cs desorption was completed through enhanced diffusion of Mg2+ cations into collapsed interlayer space under hydrothermal condition resulting in subsequent interlayer decollapse and readily release of Cs+.

Removal of cesium ions from clays by cationic surfactant intercalation

We propose a new approach to remediate cesium-contaminated clays based on intercalation of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) into clay interlayers. Intercalation of DTAB was found to occur very rapidly and involved exchanging interlayer cations. The reaction yielded efficient cesium desorption (∼97%), including of a large amount of otherwise non-desorbable cesium ions by cation exchange with ammonium ions. In addition, the intercalation of DTAB afforded an expansion of the interlayers, and an enhanced desorption of Cs by cation exchange with ammonium ions even at low concentrations of DTAB. Finally, the residual intercalated surfactants were easily removed by a decomposition reaction with hydrogen peroxide in the presence of Cu2+/Fe2+ catalysts.

Recovery of cesium from residual salt lake brine in Qarham playa of Qaidam Basin with prussian blue functionalized graphene/carbon fibers composite

Both amination graphene and carbon fibers were cross-linked together using glutaraldehyde as composite support, then, prussian blue was electrodeposited at the surface (PB/GNs/CFs). The characterization of PB/GNs/CFs by field emission scanning electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and electrochemical techniques confirmed the correct modification. Number of cubic prussian blue particles were uniformly coated at the surface with an average size of 19.32nm. Selective adsorption and desorption of cesium (Cs+) were investigated at PB/GNs/CFs in aqueous solution, respectively. At the optimum conditions, PB/GNs/CFs could be used to the recovery of Cs+ from the residual of salt lake brine which potassium was removed in Qarham playa of Qaidam Basin.