Sorption Of Europium Research Articles

Dynamic behavior of sorption of europium onto biotite flakes under the condition of saline groundwater

This study discussed the interaction between Eu and biotite in flakes under the coexistence of Na ions, considering saline groundwater. The sorption experiments were conducted by mixing an Eu solution with Na or K ions and biotite flakes at pH 5. Resultantly, the sorption of Eu gradually increased because of the diffusion into the layered structure of biotite flakes. Thereafter, the sorption amount of Eu with Na ions was less than that without Na ions, and Eu was hardly sorbed with K ions. Additionally, the apparent diffusion coefficients were estimated to be in the order of 10−13 m2/s based on a two-dimensional diffusion model. These values were lower than the effective diffusion coefficients in plutonic rock, which are employed to assess the performance of geological disposal systems. This indicates that the sorption of Eu in plutonic rock is restricted by the diffusion process in biotite flakes.Graphical abstract

Green synthesis of a potential magnetic and mesoporous EG-nZVI/CA-MCM41 nanocomposite for reductive sorption of europium

The ability of the EG-nZVI/CA-MCM-41 nanocomposite to eliminate Eu(iii) was evaluated by thermodynamic, pHZPC, speciation, kinetics analysis, adsorption isotherm, and recyclability tests, which yielded a high Eu(iii) sorption capacity of 714.28 mg g−1.

Evaluation of barium tungstate nanocrystals for the sorption of radioactive cobalt and europium from aqueous solutions

Herein, barium tungstate BaWO4 nanocrystals were chemically prepared and then estimated as inorganic sorbent material to eliminate the radioactive cobalt and europium from the waste stream. The characterization of BaWO4 nanocrystals is completed over several analytical techniques. TEM and SEM images show the formation of sphere-shaped BaWO4 structures in the nanoscale range. Also, XRD and FTIR revealed the successful preparation of BaWO4. Optimum factors affected by the sorption process are determined using batch mode. Sorption equilibrium was achieved after 60 min with the initial concentration of metal ion at 100 mg/L and at optimum pH five for both radionuclides, respectively. The different kinetic models are applied. The obtained data shows that the sorption process followed a pseudo-second order. The sorption capacity for 60Co at pH of 5 and 25 °C is 310.6 mg g−1, and 152+154Eu is 409.9 mg g−1. The thermodynamic studies illustrated that the sorption process was spontaneous and endothermic.

Europium (III) sorption on zirconium diphosphate functionalized with oxalic acid

Europium (III) sorption on zirconium diphosphate functionalized with oxalic acid

Variability of Radionuclide Sorption Efficiency on Muscovite Cleavage Planes

AbstractIn deep geological repositories for nuclear waste, the surrounding rock formation serves as an important barrier against radionuclide migration. Multiple potential host rocks contain phyllosilicates, which have shown high efficiency in radionuclide sorption. Recent experimental studies report a heterogeneous distribution of adsorbed radionuclides on nanotopographic mineral surfaces. In this study, the energetic differences of surface sorption sites available at nanotopographic structures such as steps, pits, and terraces are investigated. Eleven important surface sites are selected and the energies of ad‐ and desorption reactions are obtained from density functional theory calculations. The adsorption energies are then used for the parameterization of a kinetic Monte Carlo model simulating the distribution of adsorbed europium on a typical nanotopographic muscovite surface. On muscovite, silicon step sites are favorable for europium sorption and lead to an increased adsorption in regions with high step concentrations. Under identical chemical conditions, sorption on typical nanotopographic surfaces is increased by a factor of three compared to atomically flat surfaces. Desorption occurs preferentially at terrace sites, leading to an overall 2.5 times increased retention at nanotopographic structures. This study provides a mechanistic explanation for heterogeneous sorption on nanotopographic mineral surfaces due to the availability of energetically favorable sorption sites.

Grafting of phosphorus-containing tetrahydroxy(thia)calixarenes on silica enhances europium(III) adsorption

One pot sequential reactions of silica gel with tetrachlorosilane/triethylamine mixture and after with the conical upper rim tetraphosphorylated tetrahydroxy(thia)calixarenes yielded porous organo-inorganic sorbents modified by spatially ordered phosphonate, phosphinate or phosphine oxide groups capable of co-operative binding of metal cations. The grafting improves efficacy of europium(III) sorption by the silica gels. DFT calculations of the calixarene-Eu3+ complexes predict a calixarene flattened cone conformation with the coordination of Eu3+ cation to three of four P = O oxygen atoms and one of the aromatic systems. Adding three water molecules excludes completely cation–π interactions.

Enhanced Sorption of Europium and Scandium Ions from Nitrate Solutions by Remotely Activated Ion Exchangers.

The escalating demand for rare earth metals (REM) in situations of limited availability has spurred scientists to seek alternative sources of REM, such as industrial waste solutions. This paper investigates the potential for improving the sorption activity of readily available and inexpensive ion exchangers, specifically the interpolymer systems "Lewatit CNP LF and AV-17-8", towards europium and scandium ions, in comparison to the unactivated ion exchangers. The sorption properties of the improved sorbents (interpolymer systems) were evaluated using conductometry, gravimetry, and atomic emission analysis. The results demonstrate that the "Lewatit CNP LF:AV-17-8" (5:1) interpolymer system exhibits a 25% increase in europium ion sorption compared to the raw Lewatit CNP LF (6:0), and a 57% increase in europium ion sorption compared to the raw AV-17-8 (0:6) ion exchanger after 48 h of the sorption process. In contrast, the "Lewatit CNP LF:AV-17-8" (2:4) interpolymer system exhibits a 310% increase in scandium ion sorption compared to the raw Lewatit CNP LF (6:0), and a 240% increase in scandium ion sorption compared to the raw AV-17-8 (0:6) after 48 h of interaction. The improvement in europium and scandium ion sorption levels by the interpolymer systems, compared to the raw ion exchangers, may be attributed to the high ionization degree resulting from the remote interaction effect of the polymer sorbents as the interpolymer system in aqueous media.

Sorption and transport characteristics of europium on sandy soils

Radioactive europium can be released as a fission product during nuclear incidents and pose a threat to the human and surrounding environment because of its biological activity and long decay half-lives. For safe design issues and human health protection demands in construction of the planned nuclear power plants (NPPs) at Al-Dabaa site, it is necessary to study the sorption and transport of different radionuclides as europium within the selected area for predicting their fate at any crisis. Many soil samples were collected from different locations at the area selected along the northwestern coast of Egypt. The samples were transported to the laboratory, preserved, and characterized using X-Ray fluorescence (XRF), Fourier transform infrared spectroscopy (FT–IR), and X-Ray diffraction (XRD). Experiments were performed to study the sorption and transport kinetics of Eu(III) ions on two sandy soil samples from the collected ones. The effect of different parameters (e.g. contact time, pH, initial europium concentration, and temperature) on the sorption behavior europium was explored in a static condition. The maximum sorption capacity was determined and found to be 3.4 and 7.0 mg g−1 for sorption of Eu(III) ions onto soil-1 and soil-2, respectively. Different models were applied to assess the sorption of europium onto the surface of the investigated soils. Data confirmed that Eu retention was attained through a chemisorption process. Further, the thermodynamic parameters were determined and their values confirmed the endothermic nature of the sorption process. The transport of europium radionuclides, with groundwater, through homogeneous porous media with uniform one-dimensional flow in the geosphere was processed and the relative migration velocity was determined in presence of both distilled and seawater media. The transport of Eu(III) radionuclides was higher in presence of seawater than that in presence of distilled water by about two order of magnitude. This obviously clarified the effect of seawater in accelerating the transport of radionuclides with groundwater in the geosphere of studied area. The role of different competing ions have various valances on the relative migration velocity was explored. Further, the time required for studied radionuclides to reach Mediterranean Sea was determined.

Combining batch experiments and spectroscopy for realistic surface complexation modelling of the sorption of americium, curium, and europium onto muscovite

For a safe enclosure of contaminants, for instance in deep geological repositories of radioactive waste, any processes retarding metal migration are of paramount importance. This study focusses on the sorption of trivalent actinides (Am, Cm) and lanthanides (Eu) to the surface of muscovite, a mica and main component of most crystalline rocks (granites, granodiorites). Batch sorption experiments quantified the retention regarding parameters like pH (varied between 3 and 9), metal concentration (from 0.5 µM Cm to 10 µM Eu), or solid-to-liquid ratio (0.13 and 5.25 g·L−1). In addition, time-resolved laser fluorescence spectroscopy (TRLFS) using the actinide Cm(III) identified two distinct inner-sphere surface species. Combining both approaches allowed the development of a robust surface complexation model and the determination of stability constants of the spectroscopically identified species of (S-OH)2M3+ (logKo −8.89), (S-O)2M+ (logKo −4.11), and (S-O)2MOH (logKo −10.6), with all values extrapolated to infinite dilution. The inclusion of these stability constants into thermodynamic databases will improve the prognostic accuracy of lanthanide and actinide transport through groundwater channels in soils and crystalline rock systems.

Silica gels grafting with upper rim tetraphosphorylated tetrahydroxy(thia)calixarenes. Europium(III) sorption

Sequential treatment of silica gel with tetrachlorosilane and cone-shaped tetraphosphorylated tetrahydroxy(thia)calixarenes yielded porous organo-inorganic sorbents, the surface of which is covered by spatially ordered phosphonate, phosphinate and phosphine oxide groups capable of co-operative binding of metal cations. Sorption of europium(III) by the modified silica gels was studied.

Prediction of Europium Retention in Perovskite: Potential Candidates for an Engineering Barrier in the Disposal of Radioactive Waste

Perovskites, such as tausonite, are crystalline metal oxides with excellent optical and photocatalytic properties and have also been used successfully in the retention of metals, simulating the isotopes of uranium and plutonium. In this work, different pseudo-order and thermodynamic models were studied to achieve the prediction of the sorption of Eu3+ (chemical analogous for actinides) in tausonite. The effects of gamma irradiation and temperature on the structural characteristics of the material were determined, as an additional step in the evaluation of material as an engineering barrier in the disposal of radioactive waste. The results obtained show that the tausonite is resistant to the gamma irradiation and thermal energy. Likewise, it was possible to determine that europium sorption occurs through an exothermic and spontaneous reaction, as well as through the formation of surface complexes, where Eu3+ ions bind to sites on the tausonite by dipole-dipole interaction. Furthermore, it was shown that the sorption mechanism is influenced by diffusive phenomena, which participate in the formation of surface complexes. Additionally, a new sorption model with respect to pH was proposed, which allowed determining the physical parameter π. The evidence obtained suggests that π is a physical parameter that relates pH to an optimal value and could explain the equilibrium between the surface complexes that tausonite forms with europium. Likewise, the evidence suggests that 50 kg of tausonite would have the capacity to retain at least 26.59 g of alpha-emitting radionuclides, equivalent to a waste package (900 kg) with a maximum activity of 4000 Bq/g.

The effect of humic acid and competing cations Na+ and Ca2+ on the sorption of uranium and europium, onto bentonite from Kimolos Island (Greece)

The effect of humic acid and competing cations Na+ and Ca2+ on the sorption of uranium and europium, onto bentonite from Kimolos Island (Greece)

Revealing chemical speciation behaviors in aqueous solutions for uranium (VI) and europium (III) adsorption on zeolite

This work was conducted to examine the adsorption activity of zeolite in relation to the chemical speciation of uranium (VI) and europium (III), in especial consideration of its use for the treatment of nuclear wastewater. Adsorption experiments were conducted using batch methods with pH, ionic strength (IS), humic acid (HA), foreign ions and temperature as variables. The adsorption of uranium (VI) and europium (III) was found highly dependent on IS at pH < 8, and independent of IS at pH > 8. Comparatively, the adsorption of uranium (VI) and europium (III) was dominated by outer-sphere complexation to zeolite at pH < 8, while inner-sphere complexation was the major adsorption mechanism at pH > 8. The estimated adsorbed concentrations of uranium (VI) and europium (III) from adsorption isotherms were 50.00 mg g−1 for the U(VI) and 24.39 mg g−1 for Eu(III) under the imposed test conditions. The thermodynamic variables are evaluated from adsorption isotherms, and the outcomes show that zeolite sorption of uranium (VI) and europium (III) on zeolite is spontaneous and endothermic. This study designates zeolite as a good candidate to isolate wide-spectrum radionuclides from an aqueous solution.

Study of Sorption of Eu(III) from Various Media on TODGA-Сontaining Sorbent AXIONIT MND40T

The dependences of the static capacity (SC) of the AXIONIT MND40T sorbent based on tetraoctyldiglycolamide (TODGA) for Eu(III) on the concentration of HNO3, HCl, H2SO4, and HClO4 were determined. The SC increases with increasing acid concentration. In the concentration range 2–4 mol dm–3 SC of AXIONIT MND40T for europium in nitric, hydrochloric, and perchloric acid solutions is approximately the same, whereas in sulfuric acid solutions it is much lower. The maximum capacity and adsorption constant (Kad) in different media were calculated from the results of processing of the isotherms of europium sorption by AXIONIT MND40T. The mechanism for the extraction of europium from nitric acid solutions by AXIONIT MND40T is proposed based on the IR spectroscopy data.

Sorption of europium on diatom biosilica as model of a “green” sorbent for f-elements

Removing f-elements from anthropogenically contaminated sites is a challenging, but ecologically important task. Some of these elements are not only radioactive, but also chemically toxic and can spread through various pathways in the environment. The present work investigates f-element sorption on biogenic silica, which may be a promising “green” material for remediation. Commercially available diatomaceous earth (DE) and the cleaned cell walls of the diatom species Stephanopyxis turris (S.t.) and Thalassiosira pseudonana (T.p.) are compared with artificial mesocellular foam (MCF) as porous silica reference material. Trivalent europium was chosen as model sorptive for chemically similar trivalent actinides. Accordingly, Eu(III) in concentrations of 10−3 M and 10−5 M was sorbed on the four silica materials at varying pH values. The zeta potentials of the implemented sorbents under the same conditions were determined. In addition, the sorption reaction and the aqueous speciation of Eu(III) in the (bio)silica suspensions were modeled using the Diffuse Double Layer (DDL) model. With time-resolved laser-induced fluorescence spectroscopy (TRLFS), two different uptake mechanisms were discerned, surface adsorption and incorporation/precipitation.

Sorption behavior of Eu(Ⅲ) on Tamusu clay under strong ionic strength: Batch experiments and BSE/EDS analysis

The europium sorption on Tamusu clay was investigated by batch sorption experiments and spectroscopic study under the condition of strong ionic strength. The results demonstrated that europium sorption on Tamusu clay increased rapidly with pH value, but decreased with the ionic strength of solution increased. The europium sorption also increased in the presence of humic acid, especially at low pH value. The sorption could be fitted by Freundlich isotherm model and the europium sorption on clay was spontaneous and endothermic reaction. Besides, the result indicates that ion exchange was the main process at low pH value, while inner-sphere surface complexation dominated the sorption process at high pH value. The Backscatter electron scanning/Energy Dispersive Spectrometer(BSE/EDS) and the effect of Na for europium sorption results further suggested that europium sorption on Tamusu clay mainly competed with Na at low pH value. Overall, the results in this research were of significance to understand the sorption behavior of europium on the geological media under high ionic strength.

The sorption performance of corroded Gaomiaozi bentonite by evolved cement water at different temperatures: the case of europium removal.

In the Chinese high-level radioactive waste geological disposal program, Gaomiaozi (GMZ) bentonite has been selected as the potential buffer/backfill material. After the closure of the repository, the Ca-OH-type alkaline solution (evolved cement water) released by cement degradation may last for more than 100,000years. The bentonite will undergo the corrosion of evolved cement water (ECW) for a long period. This work focuses on the sorption property of GMZ bentonite altered by ECW. Firstly, the corrosion experiments on compacted GMZ specimens with the dry density of 1.70Mg/m3 were carried out under constant volume conditions at two temperatures. Then, the sorption of europium (Eu (III)) onto the corroded GMZ bentonite was studied by batch experiments. The results of batch sorption tests indicate that the altered GMZ bentonite keeps an effective removal property with the uptake of Eu (III) more than 99%. The effect of high-temperature conditions of the repository on the sorption property of bentonite is not significant. The results also suggest that the evolved cement water presents no detrimental effect on the long-term adsorption performance of bentonite even under higher temperature conditions.

Sorption properties of polymeric beads and films containing tetraoctyl diglycolamide towards europium (III) ions

The article presents results obtained during investigation of Eu(III) ion removal from aqueous solutions using triacetate cellulose films and styrene-divinylbenzene copolymer beads containing tetraoctyl diglycolamide (TODGA). A simple method for manufacturing films containing up to 50 % w/w TODGA is provided. Solution acidity effect on the removal rate of Eu(III) ions was studied. Maximum removal of Eu(III) ions was obtained in nitric acid solutions with concentrations of 1-6 mol/l. Additionally, increase in the europium removal rate is also observed at pH &gt; 2 for beads and in the pH range of 2 to 4 for films. In the former case increase in the removal rate is explained by increase in the nitrate ion concentration in the solution and Eu(NO3)3(TODGA)3 complex formation, and in the latter case – by decrease in TODGA protonation rate with рН growth. Observed trends indicate a high similarity in surface sorption mechanisms between the materials studied. Sorption equilibrium of Eu(III) ions onto the styrene-divinylbenzene copolymer beads impregnated with TODGA is adequately fitted to Langmuir sorption isotherm. The maximum sorption capacity of this material for Eu(III) removal from solutions with nitric acid concentration of 1 mol/l is 7.4 mg/g. It has been found that the maximum removal rate of Eu(III) ions by the triacetate cellulose films is achieved for TODGA content in the films ≥ 40 % w/w. The possibility of selective europium sorption from natural water using both beads and films is shown. Although cations present in natural water do not bind to sorbents studied, there is still slight deterioration in sorption properties when moving from model solutions to natural water. Complete desorption of Eu(III) ions from the film surface is achieved by washing three times with an EDTA solution, рН = 6.8. Prepared films can be reused for Eu(III) ion removal.

Sorption of americium / europium onto magnetite under saline conditions: Batch experiments, surface complexation modelling and X-ray absorption spectroscopy study

HypothesisThis study investigates the adsorption of americium and its chemical analogue europium on magnetite, which is expected to form as a major long-term steel canister corrosion product under anoxic and highly saline conditions. ExperimentsThe sorption of europium on magnetite (solid/liquid ratio = 0.5 g/L) was investigated batch wise in NaCl brines with ionic strength I = 1 m, 3.5 m, and 6.67 m, as a function of pHm for two europium concentrations (6 × 10−10m, 1.2 × 10−5m). Information on the chemical nature of the surface species was obtained by X-ray absorption spectroscopy (XAS) at the americium L3-edge. FindingsRetention of europium by magnetite of >99.5% was found above pHm 6.4 for all ionic strengths for europium concentration of 6 × 10−10m. No ionic strength effect was observed in this pHm range. At 1.2 × 10−5m europium concentration, 95 ± 4% sorption was found above pHm 7.5 for I = 1 m and above pHm 8.0 for I = 3.5 m and 6.67 m. A small ionic strength effect was observed in this case. X-ray absorption spectroscopy (XAS) results are consistent with the batch sorption experiment outcomes, showing an insignificant effect of ionic strength on the pHm dependent sorption. Results from potentiometric titrations of the solid phase, batch sorption experiments and spectroscopy were interpreted consistently with a charge distribution multi-site (CD-MUSIC) triple layer surface complexation model assuming surface coordination of the metal ion via a tridentate binding mode.

Effect of DTPA on europium sorption onto quartz – Batch sorption experiments and surface complexation modeling

Sorption of radionuclides on mineral surfaces retards their migration in the environment of a repository. Presence of organic ligands, however, affects sorption and consequently influences their transport behavior. In this study, we quantify the sorption of Eu(III) onto quartz surfaces as a function of pH in the absence and presence of diethylenetriaminepentaacetic acid (DTPA). Batch sorption experiments show a pH-dependent sorption of Eu(III) on quartz. The presence of DTPA results in slightly higher sorption of Eu(III) at neutral to slightly acidic pH and considerably lower sorption at alkaline conditions. Sorption experiments were simulated using the Diffuse Double Layer Model (DDLM) with single sorption sites (≡QOH) and monodentate surface complexation. The reactions were established based on the aqueous speciation calculation under the experimental conditions, and the thermodynamic constants of surface reactions were obtained and refined by numerical optimization. Results of surface complexation modeling show the formation of a surface species ≡QOHEuDTPA2−, explaining the elevated sorption of Eu(III) at neutral to slightly acidic pH. In contrast, dissolved EuDTPA2− complex species are present at alkaline pH, resulting in an enhanced mobility of Eu(III).