Voltammetric study of uranyl–selenium interactions Original Research Article

Uranyl–selenium interactions were studied at two different ionic strengths (I = 0.1 and 3.0 mol/l) using square wave voltammetry. The uranyl(+6) reduction signal is only slightly affected by selenium(+4) reduction to HgSe, which appears in virtually the same potential range. On the other hand, the height and shape of the selenium stripping peak (which corresponds to dissolution of accumulated HgSe) can be significantly changed by the uranyl(+6) concentration in the solution. The type and magnitude of such effects are highly dependent on the ionic strength. As a result of uranyl(+6) interaction with selenium(+6), a coordination species UO2SeO4 is formed, whose stability constant at I = 3 mol/l (log β1 = 1.57 ± 0.01) is in very good agreement with the literature value based on spectrophotometric data. The presence of higher complexes could not be confirmed unambiguously.