Technetium sulfide formation kinetics was studied in the pH range 8−12 in presence of Na 2 S and phosphate buffer solution. The conditions for separation of Tc sulfide micro and nanoparticles were found with ultramicrocentifugation and the values of Tc sulfide solubility were demonstrated to be dependent on the Na 2 S concentration as (Tc 3 S 10+x ) = −9 × 10 −5 ln [Na 2 S]−2 × 10 −5 M. The composition of Tc sulfide precipitate was elucidated with EXAFS, RBS and chemical analyses as Tc 3 S 10+x or [Tc 3 ( 3 -S)(S 2 ) 3 (S 2 ) 3/3 ] n in agreement with recent Lukens data.

Spirulina platensis biomass is widely applied for different technological purposes. The process of lanthanum, chromium, uranium and vanadium accumulation and biosorption by Spirulina platensis biomass from single-and multi-component systems was studied. The influence of multi-component system on the spirulina biomass growth was less pronounced in comparison with the single-component ones. To trace the uptake of metals by spirulina biomass the neutron activation analysis was used. In the experiment on the accumulation the efficiency of studied metal uptake changes in the following order: La(V) > Cr(III) > U(VI) > V(V) (single-metal solutions) and Cr(III) > La(V) > V(V) > U(VI) (multi-metal system). The process of metals biosorption was studied during a two-hour experiment. The highest rate of metal adsorption for single-component systems was observed for lanthanum and chromium. While for the multi-component system the significant increase of vanadium and chromium content in biomass was observed. In biosorption experiments the rate of biosorption and the Kd value were calculated for each metal. Fourier transform infrared spectroscopy was used to identify functional groups responsible for metal binding. The results of the present work show that spirulina biomass can be implemented as a low-cost sorbent for metal removal from industrial wastewater.

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