Natural and chemically modified zeolites from the Slovak Republic and Ukraine have been investigated as the adsorbents for the uptake of Cr(III). Model water solution of low radioactivity was used. The adsorption and desorption kinetics of chromium were established with the gradual radioexchange technique (tracer 51Cr) and flame AAS. The effect of the factors studied are examined and explained. The sorption coefficient , distribution coefficient KD, sorption capacity , sorption rate S, and leachability of Cr were calculated in neutral, alkaline and acidic aqueous solutions. The sorption capacity of the modified zeolites was found to be greater by a factor of 2 to 16 than that of the unmodified ones depending on the modifying solution applied. The leachability of chromium from loaded zeolites into the neutral solution was negligible. The leachability into alkaline and acidic solutions increased over 40%.
The Fe(III) uptake from aqueous solutions by natural and chemically modified zeolites was investigated using a gradual radioexchange
method and AAS technique. The leachability of Fe(III) from loaded zeolites was studied too. The Fe-uptake reached the value
of 60 mg·g−1 for the zeolite chemically treated with 6 mol·l−1 solution of NaOH and it is more than twelve times higher than that of the raw zeolite. The leachability of the loaded zeolite
samples in water and alkaline solution was up 5%. The leachability of the same zeolites in acid solution depended on the concentration
of modifying solution. The leachability at pH=2.6 in the range 2–20% at pH=1.9 was many times higher. The results of the radioexchange
and AAS methods were compared.
Authors:J. Tölgyessy, M. Harangozó, and P. Dillinger
Radionuclide X-ray fluorescence method with Si/Li semiconductor detector and238Pu exciting source was used for the determination of Cu, Ni, Zn and Pb in plant samples (Taraxacum officinale) from various localities near the highway D-61 Bratislava-Trnava (SR).
Authors:M. Harangozó, J. Tölgyessy, and P. Dillinger
Radionuclide X-ray fluorescence method with Si/Li semiconductor detector and238Pu exciting source was used for the determination of Cu, Ni, Pb and Zn in soil samples from various localities near the D-61 Bratislava-Trnava highway (SFR).
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.