Adsorption studies of cesium on potassium copper nickel hexacyanoferrate(II) from aqueous solutions

Adsorption of cesium from aqueous solutions on potassium copper nickel hexacyanoferrate(II) (KCNF) has been investigated in batch experiments and optimized as a function of concentration of acids, salts and adsorbate using a radiotracer technique. The results are presented in terms of distribution coefficient, K_d (ml·g^–1). The uptake of cesium obeys a Freundlich adsorption isotherm over the concentration range of 3.7 to 37 mmol·l^–1 with b values of 0.77, 0.68 and 0.56 at temperatures of 293, 313, 333 K, respectively. The Langmuir adsorption isotherm is followed in the concentration range of 15 to 75 mmol·l^–1 in the same temperature range. The values of limiting adsorption concentration (C_m) have been found to be 2.58, 2.44 and 2.32 mmol·g^–1. The heat of adsorption was calculated as 26.43 kJ·mol^–1. The influence of a number of anions and cations on cesium retention has also been studied. Column experiments have been performed and breakthrough have been obtained under different operating conditions. The low cesium capacity of 1.1 mmol·g^–1 has been obtained under dynamic conditions as compared to batch experiments. Desorption of cesium from the column has been achieved (45.4%) by nitric acid solution of 8M concentration at a flow rate of 0.5 ml·min^–1.     

Preparation and characterization of potassium copper nickel hexacyanoferrate(II) as an ion exchanger for cesium

Potassium copper nickel hexacyanoferrate(II) [KCNF] was prepared by treating potassium nickel hexacyanoferrate(II) with copper nitrate solution in 0.1M HNO₃. The resulting material was dried at various temperatures. Chemical analysis, i.r., thermal decomposition and surface property measurements were used to characterize the material. The adsorption of cesium from aqueous solutions on KCNF was investigated and optimized as a function of equilibration time and pH. The material dried at 110°C was found to be fairly stable in dilute acids, salt solutions, high doses of gamma-radiation and at high temperature. It also showed better surface properties and a high value of ion exchange capacity (2.25 mmol·g^–1) for cesium.     

Absorption of cesium on potassium cobalt hexacyanoferrate(II)

Potassium cobalt hexacyanoferrate(II) was synthesized with a composition K_1.70Co_1.12Fe(CN)₆ · 1H₂O, a mixture of K₂[CoFe(CN)₆] (85–88%) and K₂[CoFe(CN)₆] (12–15%). Ion exchange was found to be stoichiometric, the exchangeable ions being potassium and cobalt in the ratios presented for the corresponding phases. The effective capacity for cesium was 0.35 meq/g, which is only 6% of the theoretical capacity. Cesium is probably only absorbed as a monolayer on the surface of the crystallites.     

Modeling adsorption of copper (II) onto fly ash and bentonite complex from aqueous solutions

Transportation of copper (II) ions from aqueous solutions to a fly ash and bentonite complex amorphous heterogeneous oxides (AHO: CaO-SiO(2)-Al(2)O(3)-MgO-FeO) system was studied. The particles of the fly ash and bentonite complex AHO system were highly porous and composed of platelike grains. They provide the physical basis for establishing a liquid-solid reaction model applicable to mesoporous solids. The main innovation of this model was in simplifying the powder granules to aggregates of close particles, while the particles act in accordance with the model better. The calculated curves from the models were well in line with the experimental results.     

Thermochemical study of the complex formation of copper(II) and nickel(II) iminodiacetates with amino acids in aqueous solutions

The formation of mixed-ligand complexes in the M(II)–Ida–L systems (M = Cu, Ni, L = His, Orn, Lys), where Ida is the iminodiacetic acid residue, was studied by pH-metry, calorimetry, and spectrophotometry. The thermodynamic parameters (logK, Δ_rG⁰, Δ_rH, Δ_rS) of formation of the complexes were determined at 298.15 K and the ionic strength I = 0.5 (KNO₃). The most probable mode of coordination of the chelating agent and the amino acid in the mixed-ligand complexes was elucidated.     

Amine-functionalized graphene oxide/zinc hexacyanoferrate composites for cesium removal from aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - Amine-functionalized graphene oxide/zinc hexacyanoferrate (amino-rGO/ZnHCF) composites were successfully synthesized for the removal of Cs+ from...     

Equilibrium and kinetic studies of the sorption of cesium by potassium nickel hexacyanoferrate complex

In the framework of Actinex program, C.E.A. launched studies for the recovery of long lived nuclides from spent fuel dissolution acidic solutions in order to destroy them by transmutation or to encapsulate them in specific matrixes. Efforts were focused on⁹⁹Tc and¹³⁵Cs which are among the most harmful elements because of their long half live (2.1·10⁵ and 2.3·10⁶ years, respectively) and mobility. The aim of this work is to examine the possible coextraction of the pertechnetate with cesium by calix[4]arenes bis-crown-6 and then to separate if from cesium by using a second calixarene.     

Spectrophotometric study of the equilibria in aqueous copper(II) azide solutions

The reaction between copper (II) and azide has been studied spectrophotometrically at four wavelengths, at 25 degrees , and ionic strength 4.00M (sodium perchlorate). The formation constants beta(2) and beta(3) found are 2.90 +/- 0.08 x 10(4) and 3.02 +/- 0.07 x 10(6) respectively. The results obtained from potentiometric measurements with a solid-state electrode disagree with those calculated from the spectrophotometric data. Causes of the discrepancy are discussed.     

A study of the static and dynamic adsorption of Zn(II) ions on carbon materials from aqueous solutions

The effect of surface oxidation, solution pH, and ionic strength on the adsorption of Zn(II) ions from aqueous solution under static conditions was studied using commercial activated carbons in the form of grains and cloth. In addition, the effects of surface oxidation and the presence of dissolved natural organic matter (tannic acid) were studied under dynamic conditions using activated carbon cloth column beds. Under static conditions, surface oxidation largely increased Zn2+ uptake and two H+ ions were displaced from the oxidized carbon surface per Zn(II) ion adsorbed. It is proposed that adsorption of Zn(II) on the as-received basic carbons was due to C(pi)-cation interactions. An increase in solution pH in the range 3-6 increased Zn(II) uptake, whereas an increase in ionic strength decreased Zn(II) uptake because of the screening effect of the added salt. In the experiments carried out with carbon column beds, the oxidized activated carbon cloth was also more effective than the as-received carbon to remove Zn(II) ions. In this case, the presence of tannic acid decreased the efficiency of the oxidized activated carbon cloth bed to remove Zn(II) ions. An increase in the tannic acid initial concentration had a greater effect on the removal of tannic acid than on the removal of Zn(II) by the column bed. This may be a consequence of the greater size of tannic acid molecules and their low affinity for oxidized carbon surfaces.     

Alginate-enfolded copper hexacyanoferrate graphene oxide granules for adsorption of low-concentration cesium ions from aquatic environment

Alginate-enfolded copper hexacyanoferrate (CuHCF) graphene oxide granules (CGAGs) were prepared and showed excellent mechanical strength and water-swelling resistance. The maximum adsorption capacity was 50.5 mg/g. The distribution coefficient reached the maximum at pH 5.0, and was almost unaffected by the coexisted metal ions (K⁺, Na⁺, Ca²⁺, Mg²⁺, less than 20 mg/L). With the flow rate of 1.2 mL/min and the feed concentration of 20 mg/L, the efficiency of the fixed-bed column was calculated as 60.6%. These results suggested that CGAGs could be an alternative adsorbent for removing low-concentration cesium from the contaminated potable water and surface water so on.

     

Hydrated cobalt(II) and nickel(II) ammine diphosphates isolated from aqueous solutions

Hydrated amorphous cobalt and nickel(II) ammine diphosphates were prepared.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1421–1424.Original Russian Text Copyright © 2004 by Voitenko, Zhilyak, Kopilevich.     

Lithium,rubidium and cesium ion removal using potassium iron(III) hexacyanoferrate(II) supported on polymethylmethacrylate

Potassium iron(III) hexacyanoferrate(II) supported on poly methyl methacrylate, has been developed and investigated for the removal of lithium, rubidium and cesium ions. The material is capable of sorbing maximum quantities of these ions from 5.0, 2.5 and 4.5 M HNO₃ solutions respectively. Sorption studies, conducted individually for each metal ion, under optimized conditions, demonstrated that it was predominantly physisorption in the case of lithium ion while shifting to chemisorption with increasing ionic size. Distribution coefficient (K _d) values followed the order Cs⁺ > Rb⁺ > Li⁺ at low concentrations of metal ions. Following these findings Cs⁺ can preferably be removed from 1.5 to 5 M HNO₃ nuclear waste solutions.     

Partial purification of neutron-activation 99Mo from cross-contaminant radionuclides onto potassium nickel hexacyanoferrate(II) column

Potassium nickel hexacyanoferrate(II) matrix was prepared and characterized. Purification of neutron-activation ⁹⁹Mo–molybdate(VI) solutes from some residual cross-contaminant radionuclides including ¹³⁴Cs, ⁸⁶Rb, ¹²⁴Sb, ⁶⁰Co and ⁵¹Cr was carried out onto small chromatographic columns of the matrix (each of 1.0 g). Gamma-ray spectrometric analysis data showed that the purification process was not affected by either Mo(VI) concentrations (0.13 and 0.02 M Mo) in the feeding solution of 3.5 M NaNO₃ at pH 9.5 or flow rates (0.2 and 5.0 mL/min) at room temperature. Molybdenum(VI) average loss onto the column matrix did not exceed 7.7 × 10^?2 mmol Mo. Except for ⁵¹Cr, the matrix has very high selectivity for ¹³⁴Cs, ⁸⁶Rb and ¹²⁴Sb with ~50% ⁶⁰Co elimination. The obtained data were briefly discussed.     

Biosorption of copper(II) from aqueous solutions by Spirogyra species

Batch studies were conducted to investigate the kinetics and isotherms of Cu(II) biosorption on the biomass of green alga Spirogyra species. It is observed that the biosorption capacity of the biomass strongly depends on pH and algal dose. The maximum biosorption capacity of 133.3 mg Cu(II)/g of dry weight of biomass was observed at an optimum pH of 5 in 120 min with an algal dose of 20 g/L. Desorption studies were conducted with 133.3 mg/g of Cu(II) loaded biomass using different desorption agents including HCl, EDTA, H2SO4, NaCl, and H2O. The maximum desorption of 95.3% was obtained with HCl in 15 min. The results indicate that with the advantages of high metal biosorption capacity and satisfactory recovery of Cu(II), Spirogyra can be used as an efficient and economic biosorbent material for the removal and recovery of toxic heavy metals from polluted water.     

Adsorption of copper(II) ions from aqueous solutions on alumina industrial wastes

Equilibrium adsorption of copper(II) ions on red mud (alumina industrial wastes) modified by various methods was studied. The effect exerted by the nature the modifier (NaHSO₄, NaCl + HCl, and H₂SO₄) on the sorption activity of red mud was determined.