This paper deals with a study of the biosorption of UO22+ ions on two green algae: Chlorella vulgaris and Dunaliella salina. By investigating the retention degree versus contact time from Langmuir and Freundlich biosorption isotherms, kinetic investigations and FTIR spectra it was found that the biosorption process was greater for Chlorella vulgaris than for Dunaliella salina. A new kinetics method is proposed to establish the reaction order concerning the biosorption process of uranyl ions on these biomasses. [...]
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This study concerns the removal of the 137Cs+ and 60Co2+ β+γ-radioactive ions in Azolla caroliniana Willd. water fern. The living fern and two different types of biosorbent prepared from Azolla caroliniana were tested to remove the above-mentioned radioactive ions from dilute solutions, in the absence and in the presence of the ionic competition. Effective 137Cs+ and 60Co2+ ions removal from low radioactive wastewaters was demonstrated. The time dependent K d(t) values were calculated from the absorption data. These results indicate that removal process achieved equilibrium in about 120 min and that it involves two steps: rapid and slow absorption; the active process (metabolic bioaccumulation on the living fern) was responsible for above one half of the total removal process. A thin layer radiochromatography study leads to the conclusion that the biochemical components in which 137Cs+ and 60Co2+ place themselves are of a polysaccharide and lipoid fractions.
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This paper reports a study of the decomposition of water by gamma radiolysis in the presence of zeolites ZSM-5, SAPO-5, and MOR. The irradiation is performed using 60Co as a source with 1.12×1015 Bq activity at a 8.3 kGy/h dose rate. The stable products of radiolysis as well as the other chemical species are measured by mass spectrometry. The calculated radiation yield (GH 2) generally decreases in the order: H-ZSM-5>Na-ZSM-5>H-SAPO-5>MOR under the given experimental conditions; the yield is higher in the presence of these catalysts than in their absence.
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