On uranium(VI) adsorption on activated carbon

The uranium adsorption on activated carbon from dilute solutions was studied as a function of pH, uranium concentration and ageing time. Optimum conditions for quantitative adsorption of uranium from water solutions were determined: uranium concentration 2.5x10-4 g/dm3 or less; fresh prepared solutions with ageing time not more than one hour have to be used at pH 7.5-8.5; contact time not less than 20 min. The relative version of instrumental neutron activation method was used for the uranium analysis. Samples and standards were consecutively irradiated with Cd filter at a flux density of 1011nxcm-2xs-1. The standards were used also as monitors. Irradiation time: 3 min, cooling time: 10 min, and measuring time: 5 min using a Cd filter of 1 mm thickness, and determination of the uranium from the 74.7 keV γ-line of the 239U isotope (T = 23.34 min), were optimum conditions for the present analysis. Relative square deviation, related to the statistical character of decay, was not greater than 5%. Total square deviation dependent on diluting of the solutions, weighing, radiation geometry and counting geometry was estimated to be not greater than 20%. (T.G.)