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A. M. S. — Thilsing-Hansen T. — Jorgensen R. J. — 2003 — Aspects of physiological effects of sodium zeolite A supplementation in dry, nonpregnant dairy cows fed grass silage — Acta Veterinaria Scandinavica. (Suppl 97): 97
Gutzmirtl Draženka, Kralik Gordana, Margeta V., Škrtić Z., Hanžek Danica: (2006) Influence of zeolite on the fattening and slaughtering traits of pigs, Krmiva 48,3; 121–129 Danica H
Removal of fission products from mixed solvents using zeolites
II. Caesium and strontium removal
Abstract
The solvents tributylphosphate (TBP) and odourless kerosene (OK) are widely used to extract plutonium(IV) and uranium(V) in nuclear processing plants. Their use depends upon their relatively low affinity for fission products, but small amounts of radioisotopes are taken up by them. To aid disposal/reuse of these solvents it is of use to study ways of removing radioisotopes of Cs and Sr from them. This paper describes simple distribution coefficient (K d ) measurements to test the ability of aluminosilicate zeolites to remove137Cs and90Sr/90Y from TBP, OK and their mixtures.
The temperature-programmed desorption (tpd) of the amount of ammonia which is preadsorbed at about 373 K at HZSM-5 zeolites yields a complex desorption curve consisting of two overlapped peaks (Β andγ peak). Parts of the ammonia desorbed can be attributed to SiOHAl groups considering also1H-MAS NMR measurements.
Summary
Natural zeolite, clinoptilolite was tested for its ability to remove uranium from aqueous solutions. Influence parameters to the sorption process, such as initial uranium concentration, pH, contact time and temperature were investigated. Distribution coefficients of uranium on clinoptilolite were measured by batch technique. Experimental isotherms evaluated from the distribution coefficients were fit to Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models. Values of ΔH and ΔS were found as 0.93 and 56.09 J/mole, respectively. It was observed that the adsorption process is endothermic. Kinetics of uranium sorption was investigated at different time intervals at 30 °C. The reaction rate and diffusion constant were calculated.
Removal of fission products from mixed solvents using zeolites
I. Ruthenium removal
Abstract
The solvents tributylphosphate (TBP) and odourless kerosene (OK) are widely used to extract plutonium(IV) and uranium(V) in nuclear processing plants. Although these solvents are chosen because of their low affinity for fission products it is, nevertheless, of value to study ways of removing the small quantities of fission products, such as isotopes of Cs, Sr and Ru, which can be present in the solvents. This paper describes simple distribution coefficients (K d) measurements made to test the ability of the aluminosilicate zeolites to remove106Ru from TBP, OK, and their mixtures.
Abstract
Cesium cation exchange reaction with K, Na, Ca and Mg ions on natural and modified clinoptilolite has been studied. Batch cation-exchange experiments were performed by placing 0.5 g of clinoptilolite into 10 ml or 20 ml of 1·10−3M CsCl solution for differing times. Two type deposits of clinoptilolite zeolites from, Nižný Hrabovec (NH), Slovakia and Metaxades (MX), Greece were used for ion-exchange study. The distribution coefficient (K d ) and sorption capacity (Γ) were evaluated. For the determination of K, Na, Ca and Mg isotachophoresis method, the most common cations in exchange reaction was used. Cesium sorption was studied using 137Cs tracer and measured by γ-spectrometry.
Abstract
Programmed thermodesorption of n-butanol from Na-, La-montmorillonite, natural and commercial zeolite samples in quasi-isothermal conditions made. The new method of fractal dimension calculations from thermogravimetry data has been presented. On the basis of nitrogen adsorption-desorption isotherms from sorptometry and mercury porosimetry data the fractal dimensions of montmorillonites were calculated. The results from above independent and separated techniques were compared and good correlation were obtained.
Oxidative degradation of EVA copolymers in the presence of catalysts
Comparison among different zeolites and related materials
Abstract
A study of the catalytic degradation of EVA copolymers under air atmosphere has been carried out using thermogravimety (TG). Three commercial EVA copolymers and five zeolites and related materials catalysts have been selected. The degradation process in air atmosphere involves four main decomposition steps (as observed in TG), being more complex than the corresponding process in inert atmosphere. The presence of MCM-41, HY and H-β does not seem to noticeably affect to the overall degradation temperature, despite the temperature of maximum reaction rate for the second decomposition step being slightly displaced towards lower temperatures. Contrarily, the presence of HZSM-5 and HUSY zeolites seems to displace the main stage of the oxidative degradation process towards higher temperatures. Moreover, the relative importance of the second and third decomposition step is different depending on the amount and the nature of the zeolite mixed with the EVA sample. The results obtained show that the presence of the catalyst also enhances the formation of the carbonous residue.
Abstract
The potential uses of zeolites in the treatment of radioactive wastes may be conditioned to the physico-chemical properties of these materials. This work compares the Co sorption behavior of zeolite 4A and radiation treated zeolite 4A. Sorption experiments were performed with solutions containing labeled cobalt. No radiation effect (100 Mrad) in the zeolite structure or in the Co sorption behavior was found.
