The ion-exchange ability of NaOH-treated clinoptilolites with regard to Cs+ and Co2+ have been studied by a radiochemical method, enabling to calculate the sorption coefficient. The surface characteristics, total cation exchange capacity and X-ray structural analysis were measured as well. The measurements were done on Slovak clinoptilolite. Comment are made on a possible explanation of increasing sorption coefficient.
The uptake of plutonium from model solution of boric acid labelled with239Pu by natural sorbents was studied. The range of pH of solution was from 5.1 to 8. For the uptake of Pu were used different
natural and chemically modified natural sorbents of different mineralogical composition and from different deposits. The distribution
coefficients for plutonium uptake were calculated and the best conditions for uptake were evaluated.
Authors:M. Földesová, P. Lukáč, J. Majling, and V. Tomková
137Cs and60Co were sorbed from model solutions and waste water on chemically treated granular zeolite. The zeolite was incorporated into cement slurries based on blast furnace slag (BFS). The compressive and bending strength were measured after different times of hydration. The leaching tests were performed in water, base and acid solutions. The leachability was more pronounced only for samples in acidic solutions.
Authors:M. Földesová, P. Lukáč, P. Dillinger, V. Balek, and S. Svetík
Zeolites chemically modified with 1, 4 or 6 M aqueous solutions of NaOH were studied by DTA, TG and ETA (emanation thermal analysis) in the temperature range 201–200°C. The structural changes in the modified zeolites at room temperature and in the modified zeolites annealed at 1000°C were studied by XRD analysis. Thermal analysis demonstrated dehydration, dehydroxylation, structural changes and a glass transition. A gradual loss in crystallinity of the chemically modified zeolites was also observed. XRD analysis revealed structural changes caused by chemical treatment and also by annealing.
Authors:M. Földesová, P. Lukáč, P. Dillinger, E. Klosová, Z. Málek, E. Večerníková, and V. Balek
Zeolites from Nižný Hrabovec (Slovak Republic) were, modified with solutions of NaOH. The changes of zeolites in the temperature
range 20–1200 °C were studied by thermal analysis (DTA, TG, ETA), X-ray analysis and REM analysis. Thermal analysis showed
that the process of dehydration started between temperatures 20 and 600 °C, over this temperature the dealumination and structural
changes have taken place. X-ray analysis and REM analysis showed the structural changes of natural zeolites and gradual loss
of cristallinity of the chemically modified zeolites.