Instrumental neutron activation analysis (INAA) of sorption and desorption of Ag and U of microorganisms

At present, capacity of the microorganism sells to accumulate the metal ions is being studied and several bio-sorbents are already used for extracting nonferrous and noble metals (Cu, Au) in metallurgy. INAA applied for search more effective bio- sorbents U and Ag among 9 and 47 strains of actinomyces, respectively. Biomass of strains were tested on the U and Ag sorption capacity from model solutions, contained 50 mg/l ions U and Ag, respectively. Interaction between biomass and solutions took place for 15-60 min. 0.l ml solutions after sorption were dropped on the strips of ash free filter paper, which were dried (samples) and then in the aluminium packets were put in container for irradiation in nuclear reactor. The U and Ag samples were irradiated for 5 and 20 hours at neutron flux fission spectra of the density of 5.3·1013 cm-2s-1, respectively. The content of the Ag was calculated from gamma-line intensities of radionuclide 110Ag(T1/2 = 255 d, Egamma=657.7 KeV). The content of the U was calculated from gamma-lines (228.2, 277.8 KeV) intensities of 239Np radionuclide, resulted from the reaction. The U and Ag error of determining (Sr relative standard deviation) was 0.07-0.1. It was shown, that all strain of actinomyces absorbed the U and Ag from solutions to a different extent. More effective strains with activities 80.4-90.0 % were 7 of 47, absorbing Ag. Two of 9 strains, absorbing U, had activity 99.0 %, the rest had from 20.0 to 50.0 %. The activity sorption of strains has been found to increase up to 93-95 % in the temperature range of 23.5 to 42 deg. C and decrease down to 92 % at 70 deg. C. It was shown, that more effective desorption of strains (up 90 %) occurs in 5 or 10 % ammonia