Sorption and desorption of Eu(III) on alumina

Summary Effects of ionic strength and of fulvic acid on the sorption of Eu(III) on alumina were investigated by using a batch technique. The experiments were carried out at T=25±1 °C, pH 4-6 and in the presence of 1M NaCl. The results indicate that sorption isotherms of Eu(III) are linear at low pH values. The sorption-desorption of Eu(III) on alumina at pH 4.4 is reversible, but a sorption-desorption hysteresis is found at pH 5.0. Fulvic acid has an obvious positive effect on the sorption of Eu(III) on alumina at low pH values. The migration of Eu(III) in alumina was studied by using column experiments and ^152+154Eu(III) radiotracer at pH 3.8. For column experiments, Eu(III) sorbed on alumina can be desorbed completely from the solid surface at low pH values. The findings are relevant to the evaluation of lanthanide and actinide ions in the environment.     

Sorption of Eu(III) on GMZ bentonite in the absence/presence of humic acid studied by batch and XAFS techniques

Bentonite has been extensively studied because of its strong sorption ability and low permeability. In this work, the Na-bentonite from Gaomiaozi County (China) has been characterized by XRD, FTIR and acid-base titration. The sorption of Eu(III) on Na-bentonite in the absence/presence of humic acid (HA) was studied at T = 25 ± 2 °C and in 0.01 mol/L NaClO₄ solution. The effects of pH, HA, contact time and initial Eu(III) concentrations were also investigated. The results indicate that the sorption of Eu(III) on Na-bentonite was dependent on pH values. The presence of HA had little effect on Eu(III) sorption at low pH values, but decreased Eu(III) sorption at high pH values. X-ray absorption fine structure spectroscopy (XAFS) was applied to characterize the local structural environment of the adsorbed Eu(III) on bare Na-bentonite and HA-bentonite hybrids. The results indicate that Eu(III) was bound to O atoms at a distance of about 2.39 Å at pH 4.15. The results are crucial for the evaluation of the sorption and migration of other trivalent lanthanides and actinides in bentonite as backfill materials.     

Effect of pH, ionic strength, foreign ions and temperatures on the sorption of Eu(III) on attapulgite-iron oxide magnetic composites

In this paper, the attapulgite-iron oxide magnetic composites were synthesized by coprecipitation method and were characterized by SEM, XRD and FTIR in detail. The characterization results indicated that the iron oxide was successfully formed on the surface of attapulgite. The prepared attapulgite-iron oxide magnetic composites were applied as adsorbents to remove Eu(III) from aqueous solutions by using batch sorption experiments under different experimental conditions. The sorption properties of Eu(III) on bare attapulgite were also performed as comparison. The results indicated that the sorption of Eu(III) on attapulgite-iron oxide magnetic composites was strongly dependent on pH and temperature. The attapulgite-iron oxide magnetic composites can be separated from aqueous solutions using magnetic separation method in large scale. At low pH values, the sorption of Eu(III) was influenced by ionic strength and pH obviously, while the sorption of Eu(III) was not affected by ionic strength at high pH values. The sorption of Eu(III) was dominated by ion exchange or outer-sphere surface complexation at low pH values, and mainly by inner-sphere surface complexation at high pH values. The thermodynamic parameters (i.e., ?G ^°, ?S ^°, ?H ^°) calculated from the temperature dependent sorption isotherms indicated that the sorption of Eu(III) on attapulgite-iron oxide magnetic composites was an endothermic and spontaneous process. Although the sorption capacities of Eu(III) on attapulgite-iron oxide magnetic composites were a little lower than those of Eu(III) on bare attapulgite, the magnetic separation in large scale is suitable for the application of the magnetic composites in the preconcentration of Eu(III) from large volumes of aqueous solutions in possible real applications.     

Sorption of radioeuropium onto attapulgite: effect of experimental conditions

Batch sorption experiments were performed to remove Eu(III) ions from aqueous solutions by using attapulgite under ambient conditions. Different experimental conditions, such as contact time, solid content, foreign ions, pH, ionic strength, fulvic acid and temperature, have been investigated to study their effect on the sorption property. The results indicated that the sorption of Eu(III) onto attapulgite was strongly dependent on pH, ionic strength and temperature. The sorption increased from about 8.9 to 90% at pH ranging from 2 to 6 in 0.01 mol/L NaNO₃ solution. The Eu(III) kinetic sorption on attapulgite was fitted by the pseudo-second-order model better than by the pseudo-first-order model. The sorption of Eu(III) onto attapulgite increased with increasing temperature and decreasing ionic strength. The Langmuir and Freundlich models were used to simulate the sorption isotherms, and the results indicated that the Freundlich model simulated the data better than the Langmuir model. The thermodynamic parameters (∆G ^o, ∆S ^o, ∆H ^o) were determined from the temperature dependent isotherms at 298.15, 318.15 and 338.15 K, and the results indicated that the sorption reaction was an endothermic and spontaneous process. The results suggest that the attapulgite is a suitable material as an adsorbent for preconcentration and immobilization of Eu(III) from aqueous solutions.     

Effects of pH and Concentration on Cs Ions Sorption and Diffusion in Crushed Granite by Using Batch and Modified Capillary Method

A comprehensive evaluation of Cs ions sorption to and diffusion in crushed granite was conducted in this study. The sorption capacity of crushed granite suggested by the Langmuir model was 5.48 × 10^?6 mol‐Cs/g‐granite. The distribution coefficient (Kd) was around 7.5 mL/g and pH independent. By using an in‐diffusion method with a modified capillary column, some diffusion relevant parameters of Cs ions in crushed granite were derived. The apparent diffusion coefficient (Da) seemed unaffected by Cs concentration (1.15 × 10^?10 to 2.82 × 10^?10 m²/s, at 10^?7 and 10^?3 M, respectively). The determined effective diffusion coefficients (De) were located in the window from 8.59 × 10^?10 (10^?7 M) to 1.69 × 10^?9 (10^?3 M) m²/s. Under various pH environments, pH independent Da (9.0 × 10^?9 m²/s) and De (1.0 × 10^?9 m²/s) values were observed. Under current systems, consistently higher De than Da implied the diffusion of Cs ions was governed by surface diffusion phenomenon. Whereas the pH insensitive feature indicated the Cs sorption to crushed granite was mainly through ion‐exchange reaction. Moreover, further SEM/EDS mapping clearly showed the adsorbed Cs ions were highly concentrated on the fracture surface of biotite.     

Sorption separation of Eu and As from single-component systems by Fe-modified biochar: kinetic and equilibrium study

The utilization of carbonaceous materials in separation processes of radionuclides, heavy metals and metalloids represents a burning issue in environmental and waste management. The main objective of this study was to characterize the effect of chemical modification of corncob-derived biochar by Fe-impregnations on sorption efficiency of Eu and As as a model compounds of cationic lanthanides and anionic metalloids. The biochar sample produced in slow pyrolysis process at 500 °C before (BC) and after (IBC) impregnation process was characterized by elemental, FTIR, SEM-EDX analysis to confirm the effectiveness of Fe-impregnation process. The basic physico-chemical properties showed differences in surface area and pH values of BC- and IBC-derived sorbents. Sorption processes of Eu and As by BC and IBC were characterized as a time- and initial concentration of sorbate-dependent processes. The sorption equilibrium was reached for both sorbates in 24 h of contact time. Batch equilibrium experiments revealed the increased maximum sorption capacities (Q _max) of IBC for As about more than 20 times (Q _max BC 0.11 and Q _max IBC 2.26 mg g^?1). Our study confirmed negligible effect of Fe-impregnation on sorption capacity of biochar for Eu (Q _max BC 0.89 and Q _max IBC 0.98 mg g^?1). The iron-impregnation of biochar-derived sorbents can be utilized as a valuable treatment method to produce stable and more effective sorption materials for various xenobiotics separation from liquid wastes and aqueous solutions.     

Sorption studies of europium(III) on hydrous silica

Summary Sorption behavior of europium, Eu³⁺, on SiO₂ ^. xH₂O (silica gel) has been investigated as a function of time, the amount of silica gel, Eu³⁺ concentration, the ionic strength, and pH (in absence and in presence of carbonate). The sorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. The sorption capacity of silica gel was determined to be in the range of (2.62-8.00) ^. 10^-7 mol/g at pH 5.30±0.05 and 0.20M NaClO₄. The mean energy of sorption was calculated to be 13.50±0.05 kJ/mol from the D-R isotherm, suggesting the involvement of ion-exchange reactions in the sorption process. Sorption of Eu³⁺ decreased with increased ionic strength. A gradual decrease in pH with increased ionic strength supports the involvement of an ion-exchange mechanism in the sorption process. The diffusion coefficient of Eu³⁺ ion on silica gel was calculated as (3.98±0.12) ^. 10^-13 m^{2 .} s^-1 under the particle diffusion-controlled conditions.     

Sorption of americium from low-level liquid wastes by nanocrystalline MnO2

Nanocrystalline MnO₂, synthesized by alcoholic hydrolysis of KMnO₄, has been studied as a sorbent for removal of americium from low level liquid waste solutions. The synthesized MnO₂ was found to have BET surface area of 230 m² g^?1. Am(III) was found to be sorbed by MnO₂ quantitatively within 15 min at pH 5. The sorption was found to be more than 90 % at as low a pH as 1.2 and reached to near 100 % at all pH values above pH 3.0 There was no effect of ionic strength (0.01–1.0 M NaCl, CaCl₂) on the sorption suggesting the sorption following inner sphere complexation mechanism at all the pH values. Adsorption isotherm studies were carried out using Eu(III) as a chemical analogue of Am(III). These studies showed the isotherm data to follow Langmuir adsorption isotherm.     

Insights into sorption species of Eu(III) on γ-Al2O3 and bentonite under different pH: Studies at macro- and micro-scales

The sorption species of Eu(III) on γ-Al₂O₃ and bentonite was investigated by batch, surface complexation model (SCM), and X-ray absorption spectroscopy (XAS). The results showed that sorption edges of Eu(III) on γ-Al₂O₃ and bentonite were as expected shifted forward high pH with the increasing in Eu(III) concentration, and sorption of Eu(III) was strongly dependent on pH. In γ-Al₂O₃ system, sorption of Eu(III) was decreased above pH 8.5 at low concentration of Eu(III) because of water soluble carbonate species of Eu(III), however the decline did not appear at high concentration of Eu(III) possibly due to a offset effect of surface precipitation. Actually, the sorption species of Eu(III) on bentonite mainly referred to at least four kinds of species including ion exchange (>X₃Eu⁰) at low pH, inner-sphere complexes (>AlOEu²⁺ and >SiOEu²⁺) at neutral condition, and hydrolysis species (>SiOEu(OH) ₂ ⁰ ) at alkaline condition. Linear combination fitting (LCF) in k space testified that hydrolysis of Eu(OH)₃(s) and oxide of Eu₂O₃ species were major for Eu(III) sorption on γ-Al₂O₃, whereas Eu³⁺(aq) and hydrolysis species comprised sorption species on bentonite. Extended X-ray absorption fine structure (EXAFS) analysis further confirmed the prediction from SCM and LCF. In addition, the typical shells of Eu–Al in R range of 3.0–3.4 Å and Eu–Si at ~4.0 Å were found in radial structure functions, which was possibly identified to edge-shared bidentate of Eu(III) on Al₂O₃ and bentonite.     

Sorption of thallium(III) ions from aqueous solutions using titanium dioxide nanoparticles

Titanium dioxide nanoparticles (NPs) were employed for the sorption of Tl(III) ions from aqueous solution. The process was studied in detail by varying the sorption time, pH, Tl(III) concentration, temperature, and amount of sorbent. The sorption was found to be fast and to reach equilibrium within 2 min, to be less efficient at low pH values, and to increase with pH and temperature. The sorption fits the Langmuir equation and follows a pseudo second order model. The mean energy of the sorption is approximately 15 kJ mol^?1 as calculated from the Dubinin–Radushkevich isotherm. The thermodynamic parameters for the sorption were also determined, and the ΔH ⁰ and ΔG ⁰ values indicate endothermic behavior.     

Assessment of copper(II) biosorption from aqueous solution by agricultural and industrial residues

In this study, newspaper scraps (NS) and maize spatha (MS) treated in turn by HNO₃ and MeOH were evaluated for the biosorption of Cu²⁺ ions, on the basis of batch experiments. The effects of several parameters were investigated, including contact time, solution pH, shaking speed, biosorbent dosage and ionic strength. Under optimal conditions, the maximum sorption capacities (Q_max) were (60.386 ± 0.006) and (44.90 ± 0.02) μmol Cu²⁺ per g of sorbent, respectively, for NS and MS chemically treated with HNO₃. The optimal parameters were pH: 5, contact time: 40 min and shaking speed: 100 rpm for NS, while for MS the same parameters were pH 5, 20 min and 150 rpm, respectively. It was found that Cu²⁺ biosorption is disfavored by an increase in ionic strength and by the presence of some interfering cations. The experimental data obtained with NS best matched the Langmuir’s sorption model (R² = 0.994) while the Temkin model best described biosorption on MS (R² = 0.987). The biosorption of Cu²⁺ on both materials followed pseudo-second order kinetics, and the desorption of Cu²⁺ ions was effective in 0.01 M HCl solution.     

Sorption studies of europium on cerium phosphate using Box-Behnken design

Amorphous cerium phosphate was prepared and characterized. Three-level Box-Behnken design (BBD) was employed to analyze the effect of process variables such as initial pH (2–6), contact time (60–180 min), and sorbent amount (0.05–0.15 g) on the sorption capacity of europium. Analysis of variance (ANOVA) revealed that the main effect of initial pH and sorbent amount has a substantial impact on the sorption of Eu(III). Probability F-value (F = 3 × 10^-3) and correlation coefficient (R2 = 0.97) point out that the model is in good accordance with experimental data. The maximum sorption capacity of Eu(III) was found to be 42.14 mg g^-1 at initial pH 6, contact time of 180 min, and a sorbent amount of 0.05 g. Sorption isotherm data was well explained by the Langmuir model and monolayer Eu(III) sorption capacity was obtained as 30.40 mg g^-1. Kinetic data were well described by the pseudo-second-order model. Thermodynamic data suggested that the process is endothermic and spontaneous.     

Sorption of nickel on chitosan

The sorption of nickel on chitosan was studied using batch method. As a tracer was used radioisotope ⁶³Ni. The effect of pH and contact time to reach sorption equilibrium was investigated. During the sorption of Ni²⁺ ions occur mostly to ion-exchange reactions on the surface of sorbent. The time to reach the sorption equilibrium of nickel on chitosan was 14 h. The percentage of sorption after 14 h achieved the value of 84 %. On the sorption of nickel used solutions with initial pH in the range from 3.9 to 8.1. In the monitored range of pH after 24 h of contact was the sorption of nickel on chitosan >97 %. The sorption of nickel was reduced by increasing concentrations of Ni²⁺ ions in the solution. The experimental data for sorption of nickel have been interpreted in the term of Langmuir isotherm and the value of maximum sorption capacity of nickel on chitosan was 2.71 × 10^?3 mol g^?1.     

Effect of humic acid, pH and ionic strength on the sorption of Eu(III) on red earth and its solid component

Sorption and desorption of radioeuropium on red earth and its solid components to remove organic matter was studied at pH 5.3±0.1 and 4.5±0.1, and in 0.01M and 0.001M NaClO₄ solutions, respectively. Eu(III) sorption showed strong pH and humic acid concentration dependency, and NaClO₄ concentration independency. The sorption increased with increasing pH and amount of HA adsorbed on red earth. The sorption of Eu(III) on red earth was mainly dominated by surface complexation. Humic acid and high pH had a great tendency to immobilize the movement of Eu(III) in red earth. Sorption-desorption hysteresis of Eu(III) on red earth indicated that the sorption was irreversible.     

Sorption of Eu(III) by amorphous titania, anatase and rutile

Sorption of Eu(III), an analogue of trivalent actinides (Am, Cm), by amorphous titania as well as different crystalline phases of titania, namely anatase and rutile, have been studied as a function of pH, using ¹⁵⁴Eu (half life?=?8.8 yrs, E_???=?123,247?keV) as a radiotracer. The objective of this study was to investigate the effect of the crystalline phase of the titania on their sorption behaviour towards the metal ion. Amorphous titania was prepared by organic route and was converted into anatase and rutile by heating at elevated temperatures based on the differential thermal analysis studies. Eu(III) sorption by all forms of titania rises sharply with the pH of the suspension, with the sorption edge shifting to higher value in the order; amorphous?<?anatase?<?rutile. However, the normalization of the sorption data to the surface area of the sorbents resulted in the overlapping of the sorption curves for amorphous and anatase phases, with the data being higher for rutle in the lower pH region, indicating the effect of the crystal phase on sorption behaviour of Eu(III).     

Sorption of hafnium on hydrous titanium oxide using radiotracer technique

The sorption of hafnium on hydrous titanium oxide (TiO₂·1.94 H₂O) has been studied in detail. Maximum sorption of hafnium can be achieved from a pH 7 buffer solution containing boric acid and sodium hydroxide using 50 mg of the oxide after 30 minutes shaking. The value ofk _d, the rate constant of intraparticle transport for hafnium sorption, from 0.01M hydrochloric and perchloric acid and pH 7 buffer solutions has been found to be 17 mmole·g^–1·min^–2. The kinetics of hafnium sorption follows Lagergren equation in 0.01M HCl solution only. The values of the overall rate constantK=6.33·10^–2 min^–1 and of the rate constant for sorptionk ₁=6.32·10^–2 min^–1 and desorptionk ₂=2.28·10^–5 min^–1 have been evaluated using linear regression analysis. The value of correlation factor() is 0.9824. The influence of hafnium concentration on its sorption has been examined from 4.55·10^–5 to 9.01·10^–4 M from pH 7 buffer solution. The sorption data followed only the Langmuir sorption isotherm. The saturation capacity of 9.52 mmole·g^–1 and of a constant related to sorption energy have been estimated to be 2917 dm³·mole^–1. Among all the additional anions and cations tested only citrate ions reduce the sorption significantly. Under optimal experimental conditions selected for hafnium sorption, As(III), Sn(V), Co(II), Se(IV) and Eu(III) have shown higher sorption whereas Mn(II), Ag(I) and Sc(III) are sorbed to a lesser extent. It can be concluded that a titanium oxide bed can be used for the preconcentration and removal of hafnium and other metal ions showing higher sorption from their very dilute solutions. The oxide can also be employed for the decontamination of radioactive liquid waste and for pollution abatement studies.     

Preparation and Metal Sorption Properties of GMA-MMA-DVB Microspheres Functionalized with 2-Aminothiazole

Crosslinked glycidylmethacrylate-methylmethacrylate-divinylbenzen (GMA-MMA-DVB) microspheres were prepared by suspension polymerization. The GMA-MMA-DVB microspheres with an average size of 150–300 μm and surface area of 1.51 m²g^?1 were functionalized with 2-aminothiazole (ATAL). The affinity of the functionalized microspheres for copper, iron, aluminum, lead, cobalt, and nickel ions was examined. The effects of pH, resin amount, shaking time, type, and volume of the elution solution on the sorption and desorption properties of functionalized microspheres for these metal ions were investigated using the batch method. Sorption capacities (0.97–1.12 mmolg^?1), quantitation limits (2.6–3.0 ppb) and recoveries (90–99%) were calculated.     

Sorption of uranyl ion on hydrous silica: Effects of ionic strength and ethylenediaminetetraacetic acid (EDTA)

The effects of ionic strength and of ethylenediamin et etraacetic acid (EDTA) on the sorption of uranyl ion, UO₂ ²⁺, to SiO₂·xH₂O (silica gel) were investigated. It was observed that pH and the ions present in the supporting electrolytes influence the ionic strength effects. The presence of different sodium salts in the concentration range (0.20 to 1.40M) suppressed the sorption of UO₂ ²⁺ in the order: NaNO₃ < NaClO₄ < NaCl < NaOCOCH₃ < Na₂SO₄ [pH 2.75(±0.05)], while the presence of perchlorate salts of Li⁺, Na⁺ and Ca²⁺ (0.20 to 1.40M) promoted the sorption of UO₂ ²⁺ on silica gel in the order: LiClO₄∼NaClO₄<Ca(ClO₄)₂ at pH 2.80(±0.05). The ionic strength effect on UO₂ ²⁺ sorption was studied in presence of EDTA (0–1.00·10⁻³M) in the pH range 2.90 to 5.57. The sorption data and speciation calculation suggest negligible complexation of UO₂ ²⁺ with EDTA at I≥1.00M NaClO₄. On leave from Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India.     

Sorption of iodine on Beishan granite: effect of speciation and humic acid

Sorption of iodine on Beishan granite was studied by batch method. Great difference exists in the sorption behaviors of I^? and IO₃^?. Under acidic condition, the sorption of IO₃^? improves dramatically, and IO₃^? could partly convert to I^?. However, the sorption of I^? is close to zero at all studied pH. Humic acid can slight improve the sorption of IO₃^?, but greatly improve the sorption of I^? in acidic condition. The postulated sorption mechanisms of IO₃^? are electrical interaction and followed by reduction.     

Sorption equilibria in colloid systems and their influence on distribution ratios of trace elements

Summary Trace element distribution in systems in which colloids and coarse solid particles are present is determined by the following sorption equilibria: sorption of trace elements on coarse particles A, sorption of trace elements on particles of colloidal dimensions B and sorption of B on A. Experiments are carried out by shaking kaolinite with water in the presence of Cu²⁺ at pH 4.4. The concentration of colloids in solution is determined photometrically and by ICP-AES. It increases with temperature and intensity of shaking. Distribution ratios of trace elements which are found experimentally depend strongly on the pore size of the filters used for separation of solution and solids. They often increase with the ratioV (volume of solution):m (mass of solid) which is shown to be due to the sorption equilibrium of B on A.

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Sorptionsgleichgewichte in kolloidalen Systemen und ihr Einfluß auf die Verteilungsverhältnisse von Spurenelementen

Zusammenfassung Die Spurenelementverteilung in Systemen, in denen Kolloide und Grobteilchen vorhanden sind, wird durch folgende Sorptionsgleichgewichte bestimmt: Sorption von Spurenelementen an Grobteilchen A, Sorption von Spurenelementen an Kolloidteilchen B sowie Sorption von B an A. Bei den durchgeführten Versuchen wurde Kaolinit mit Wasser in Gegenwart von Cu²⁺ bei pH 4,4 geschüttelt. Die Kolloidkonzentration in der Lösung wurde durch Photometrie und ICP-AES gemessen; sie nimmt mit steigender Temperatur und Schüttelintensität zu. Experimentell gefundene Verteilungsverhältnisse hängen stark von der Porengröße der verwendeten Filter ab. Sie nehmen oft zu mit dem VerhältnisV (Lösungsvolumen):m (Masse der festen Substanz), was durch das Sorptionsgleichgewicht von B an A verursacht ist.