Uptake of uranyl ions from uranium ores and sludges by means of Spirulina platensis, Porphyridium cruentum and Nostok linckia alga.

In this paper was studied the uranyl ions biosorption on three types of alga: Nostok linckia, Porphyridium cruentum and Spirulina platensis. These ions were supplied either from a pure solution of uranyl nitrate, or after leaching process of uranium ore, or from the sludge resulting in the output of pure UO(2) technology. It was investigated the retention degree versus contact time and afterwards the Langmuir and Freundlich biosorption isotherms of uranyl ions on the three alga types. The retention of UO(2)(2+) ions on alga was proved through FTIR spectra plotted before and after biosorption processes. From the experimental data it was found that regardless of origin of uranyl ions, the retention degree on alga decreased in the series. Spirulina platensis > Porphyridium cruentum ≥ Nostok linckia.

Effect of radioactive and non-radioactive mercury on wheat germination and the anti-toxic role of glutathione.

Studies to test the noxious effect of mercury ions on wheat germination and seedling growth showed that germination rate, shoot length, and fresh weights varied as a function of their concentration in the treatment solutions. At the same concentration, the radioactive mercury proved to be more harmful to the living seeds and seedlings. The detoxification action of glutathione for both radioactive and non-radioactive mercury was also followed. After a seven-day period of germination in the presence of the investigated compounds, the wheat plantlets were cut from the seeds, and their height, weight, and residual radioactivity were measured. The shoot length decreased from 8.1 (blank) to 4.6 cm (non-radioactive mercury) or even to 2.5 cm ((203)Hg), while glutathione had both an anti-toxic and an anti-radiotoxic effect (6.4 and 6.0 cm, respectively). The root weight of the lot decreased from 1.7 to 0.7 g and 0.4 g, respectively, while glutathione showed a healing action (1.5 and 1.7 g). The radioactive ions accumulated especially in roots (35.5 %), and less in shoots (11.2 %). Results were statistically validated.

Laboratory analyses of 60Co2+, 65Zn2+ and (55+59)Fe3+ radiocations uptake by Lemna minor.

The living Lemna minor vascular plant and two different sorbents obtained by chemical treatment of this plant were tested to study the removal process of 60Co2+, 65Zn2+ and (55+59)Fe3+ from low radioactive wastewaters. The most effective sorbent was the protonated biomass, indicating the decisive contribution of the complexation process in the assembly of the uptake mechanisms. The uptake performance of the biosorbent obtained from the L. minor can be increased with approximately 20% by treatment with 0.1 N HNO3. Concerning the metabolically active mechanism, it can be notice the slow elimination of 65Zn2+ and the continuously increase of (55+59)Fe3+ uptake degree. The Na2CO3 generated in situ in systems participates to a double exchange reaction with the metallic cations during the uptake. 60Co2+, 65Zn2+ and (55+59)Fe3+ radiocations prefer for coordination N-donor ligands at the expense O-donors ones.