A fine-crystalline stannous ferrocyanide (SCF) has been prepared by adding tin(II) chloride to potassium hexacyanoferrate(II) solution. The material was characterized by chemical analysis, thermogravimetry, X-ray diffraction and infrared spectra. The solubility of SCF, kinetics and sorption mechanism of palladium in hydrochloric acid solutions were investigated. The palladium exchange capacity of 2.20 mM/g dry weight have been found.
Composite sorbents based on potassium nickel ferrocyanide embedded in silica gel matrix were prepared and characterised by
powdered X-ray diffraction analysis, IR spectra, Mössbauer spectra and electron microscopy. The sorbent exhibits very good
efficiency for cesium uptake and radiation resistance. The sorption capacity for cesium ions is comparable with the capacity
for the pure ferrocyanides.
Samples of zirconium ferrocyanide have been prepared under different conditions of precipitation, and their properties, composition
and ion-exchange behaviour are reported. The distribution ratios of 21 metal ions are given and some topical separations have
been achieved using these data.
Authors:Ch. Neskovic-Loos, M. Fedoroff, and G. Revel
The adsorption behaviour of more than 50 ions has been studied under dynamic conditions on nickel ferrocyanide in various
aqueous solutions of hydrochloric, nitric, perchloric, acetic, hydrofluoric acids of 1M molarity and in a mixture of 40% 2.5M
hydrochloric acid and 60% acetone. Among the retained elements we found cations forming insoluble ferrocyanide salts and alkali
metals. On the basis of the behaviour of each element, we have found the possibilities of some radiochemical separations,
especially cesium-alkaline earth metals, arsenic-antimony, manganese-nickel in hydrochloric solution, molybdenum-technetium
in acetic solution. In order to choose the best conditions, distribution coefficients have been measured as a function of
acid molarity in the 0.01M–2M range. These separations were used for the activation analysis of various metals, for example
the determination of nickel in chromium and iron. An exchange system has been developed to retain the silver matrix quantitatively
in the determination of manganese in this metal.
Authors:W. Malik, S. Srivastava, Raj Singh, and Satish Kumar
The sorption of univalent, bivalent and trivalent ions has been studied on chromium ferrocyanide gel. The studies reveal a
high sorption capacity for Cs+, Tl+, Ag+, Cu2+, Zn2+, Cd2+, Fe3+ and Th4+. The sorption of monovalent cations show purely ion-exchange mechanism while the uptake of bivalent and trivalent cations
is non-equivalent in nature. Single elution of Rb+, Cs+ and Tl+ has been performed from the columns of this exchanger and the recovery is almost complete in all the cases. Cu2+ and Ag+ get completely adsorbed on the gel column and their elution is not possible probably due to the formation of some new solid
phases. Depending on the Kd values of the metal ions, a large number of separations of radiochemical as well as analytical importance can be performed
on the columns of this exchanger material.
In the presence of trace amounts of hydrazinium or amidosulfate ion, sufficiently high values were observed for the distribution coefficients of cesium on several insoluble ferrocyanide sorbents in a concentrated solution of nitric acid, in contrast to considerably lower values in their absence. The results indicate an inhibitory action of the above agents on the oxidation of ferrocyanide to ferricyanide with nitric acid.
Potassium ferrocyanide gives a colour reaction with U(VI), which is suitable for its determination. The complex absorbs in the wavelength range of 390–397 nm. The optimum pH range for colour development was 1.5–3.5. The molar absorptivity was found to be 4.65·103 1·mol–1·cm–1. Most of the anions up to 1000 g did not interfere. The method was made selective by extracting U(VI) first with DOSO from the mixture of interfering cations from 1–2M HNO3 medium and then determining uranium in the back-extracted solution by developing the colour with ferrocyanide. 20 g/10 ml of U(VI) in the final solution could be satisfactorily determined within an RSD of ±2%.
Authors:S. Rao, K. Lal, S. Narasimhan, and Jaleel Ahmed
A method has been developed for the removal of cesium from the aqueous radioactive waste using a composite ion-exchanger consisting
of Copper-Ferrocyanide Powder (CFC) and Polyurethane (PU) Foam. Polyvinyl acetate has been used as a binder in the preparation
of CFC-PU foam. The physical properties of CFC such as density, surface area, IR stretching frequency and lattice parameters
have been evaluated and also its potassium and copper(II) content have been estimated. Optimization of loading of CFC on PU
foam has been studied. The CFC-PU was viewed under microscope to find out the homogeneity of distribution. Exchange capacities
of the CFC-PU foam in different media have been determined and column studies have been carried out. Studies have been undertaken
on extraction of cesium from CFC foam and also on digestion of spent CFC-PU foam and immobilization of digested solution in
cement matrix. The cement matrices have been characterized with respect to density, bio-resistance and leaching resistance.
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.
Stripping of the nuclides U, Np, Pu, Am, Eu, Zr, Ru and Fe from the loaded TRUEX solvent (0.2M CMPO+1.2M TBP in dodecane) has been carried out with a potassium ferrocyanide solution. In four contacts, 98% or more of U, Pu, Am and Eu could be stripped whereas Zr and Ru recoveries were 94% and 92%, respectively. Further, the co-precipitation of Am, Pu, U and Eu on ferric ferrocyanide precipitate from the CMPO phase has shown high recovery of Am, Pu and Eu but lower for U.