Distribution Coefficients Of Cs Research Articles

ION-EXCHANGE PROPERTIES OF POTASSIUM NICKEL HEXACYANOFERRATE(II) COMPOUNDS

ABSTRACT A series of nonstoichiometric compounds K2 xNix/2[NiFe(CN)6]nH2O was prepared by varying Ni/Fe molar ratio from 0.1 to 100. The products had a face-centered cubic (fee) structure, and the lattice parameter slightly increased with decreasing K/Fe ratio. The uptake rate of Cs+ was enhanced at lower K/Fe ratio below 1.32 and reached equilibrium within 8 h for the products with K/Fe below 0.86. The distribution coefficients of Cs+ on the products were above 104 cm3/g in the presence of 1 mol/dm3 Na+, K+ or H+ while those of other nuclides were less than 102, indicating high selectivity of the product to Cs+. The uptake of Cs+ followed a Langmuir-type isotherm and the maximum amount of Cs+ adsorbed was evaluated to be 1.0 to 1.5 mmol/g. Cesium nuclides were efficiently removed from a simulated high-level liquid waste.

Ion Exchange of Cesium on Potassium Nickel Hexacyanoferrate (II)s

The ion exchange of Cs+ on a nonstoichiometric compound K0.87Ni0.57[NiFe(CN)6]·nH2O (KNiFC) was examined by batch methods. The distribution coefficient of Cs+, Kd,Cs, was independent of Na+ concentration up to 5M (=mol/dm3), while it decreased with increasing concentrations of both K+ and NH4 +. The separation factor for Cs/Rb, αcs/Rb, was 4.7×102 in the presence of 5M Na+. The decreasing order of Kd,Cs in the coexisting cations was found to be NH4 +K+, H+Na+, Ca2+. The uptake of Cs+ on KNiFC followed a Langmuir-type isotherm and the maximum amount of Cs+ taken up was estimated to be 2.57±0.074mmol/g. The free energy of K+←Cs+ ion exchange was calculated to be −15.4±1.4kJ/mol by Kielland plot.

Ion Exchange of Cesium on Potassium Nickel Hexacyanoferrate (II) s.

The ion exchange of Cs+ on a nonstoichiometric compound K0.87Ni0.57[NiFe(CN)6]·nH2O (KNiFC) was examined by batch methods. The distribution coefficient of Cs+, Kd,Cs, was independent of Na+ concentration up to 5M (=mol/dm3), while it decreased with increasing concentrations of both K+ and NH4 +. The separation factor for Cs/Rb, αcs/Rb, was 4.7×102 in the presence of 5M Na+. The decreasing order of Kd,Cs in the coexisting cations was found to be NH4 +K+, H+Na+, Ca2+. The uptake of Cs+ on KNiFC followed a Langmuir-type isotherm and the maximum amount of Cs+ taken up was estimated to be 2.57±0.074mmol/g. The free energy of K+←Cs+ ion exchange was calculated to be −15.4±1.4kJ/mol by Kielland plot.

Influence of various additives on the sorption of cesium from strong nitric acid medium on potassium cupric ferrocyanide

The inhibitory action of hydrazinium or amidosulfate ion, whose presence prevented the oxidation of potassium cupric ferrocyanide with nitric acid and thereby kept the distribution coefficient of Cs on the sorbent at very high values in strong nitric acid medium, was eluciated to be due to the removal of nitrous acid present as an impurity. Based on this interpretation, a number of chemicals capable of reacting with nitrous acid were found to be effective as inhibitors besides hydrazinium and amidosulfate ions. A new process for Cs separation was proposed on the basis of the result obtained.

Der Einsatz von Sorbentien räumlich-globulrer Struktur zur Abtrennung radioaktiver Verunreinigungen aus Wasser

Abstract Possibilities of using a new generation of sorbents have been investigated. Polymers of spatial-globular (spherulitic) structure (RGS polymers) have been tested to separate Cs, Sr and rare earth elements – which can also be radioactive contaminants – from different waters. RGS polymers are both, solids and highly-disperse systems being extremely permeable to fluids and gases with low pressure decline. They were currently used to clean industrial waste-water. It is shown that these polymers can be used successfully to separate radionuclides. Polymers RGS-81 and RGS-112 have high distribution coefficients for CS, Sr, Sc, the lanthanide series and Hf in weakly acid solutions. In HF solutions, Sc and Hf can be separated from Cs, Sr and the lanthanides.

Reduction of Cesium Leaching Ratio from Cementitious Resin Forms Using Natural Active Silica.

Cesium adsorption behavior of active silica, which is a natural acid clay composed of cristobalite and quartz, was evaluated for its applicability as Cs adsorbent to be added to cementitious waste forms containing spent ion exchange resin. Since active silica carried the Cs exchangeable silanol group (—SiOH) originally, the Cs distribution coefficient was remarkably high (<104). It increased in saturated Ca(OH)2 solution, simulating the cement paste, due to formation of new silanol groups. With its addition to the cementitious forms with 134Cs adsorbed ion exchange resin solidified by slag cement, the Cs leaching ratio was reduced to below 1/10 that without active silica.

Effect of Batch Factor on a Binary Ion Exchange Equilibrium

Abstract The relation between the distribution coefficient of Cs+ on Mn+ form exchanger and the ratio of the solution volume to the exchanger weight (batch factor) at a constant loading of Cs+ has been investigated while taking the activity coefficients of ionic species into consideration when the initial concentration of Cs+ is changed.

Effect of Heat Treatment of Hydrous Metal Oxides on Their Cation-Exchange Selectivity

Abstract The effect of a heat treatment on the ion-exchange selectivity of hydrous metal oxides was studied by measuring the distribution coefficients of Cs+, Ba2+, Co2+, and Eu3+ on hydrous oxides of TiIV, SnIV, ZrIV, and NbV. The distribution coefficients decreased with increasing temperature for the heat treatment, except on hydrous Nbv oxide, in which the reverse effect was observed (except for Cs+). The decrease in the hydrous SnIVand ZrIV oxides is ascribed to a decrease in their ion-exchange capacity. In the case of hydrous TiIV and NbVoxides, the distribution coefficients were strongly affected by a change in the acidity of the most dissociable OH groups by the heat treatment. The selectivity of the exchangers has no direct correlation with the change in the porosity, the specific surface area and the density of the materials by the heat treatment.

長石・雲母・ボーキサイトの水熱変質鉱物へのストロンチウムイオン，セシウムイオンの吸着

The minerals, from which Li+ and K+ had been extracted in high extraction ratios, had high adsorbability of Sr2+ and Cs+ ions. Hydrothermal extraction residues of lithia-mica and, feldspar had high distribution coefficients (103∼404) towards Sr2+ and Cs+ ions in the aqueous solution. Although the red mud prepared from bauxite had high distribution coefficient of Sr2+ ion, it had low distribution coefficient of Cs+ ion.These iesidues' obtained by the hydrothermal treatment of aluminosilicate ores are expected as the promising immobilization matrix of 90Sr and 137Cs found in the nuclear fission wastes.