Spectrophtometric Study of Uranyl-oxalate Complexation in Solution

Varování

Publikace nespadá pod Pedagogickou fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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HAVEL Josef SOTO-GUERRERO Julio Arturo LUBAL Přemysl

Rok publikování 2002
Druh Článek v odborném periodiku
Časopis / Zdroj Polyhedron
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Obor Analytická chemie, separace
Klíčová slova Uranyl oxalates; Oxalic acid; UV/VIS spectrophotometry; Speciation; Stability Constants; Aqeous solutions
Popis Uranyl-oxalate complex equilibrium in aqueous solution was studied by UV-Vis spectrophotometry. Due to high spectra correlation, derivative spectrophotometry was also applied during the search for the best chemical model. The absorption spectra of all the complexes were calculated and found in a good agreement with theoretical considerations. Overall protonation constants of oxalate, necessary for accurate calculation of uranyl-oxalate formation constants, were also determined under the same conditions and the following values were obtained log Beta_p_1 = 3.83 +/- 0.01; log Beta_p_2 = 4.92 +/- 0.01. Stability constants determined for the [(UO2)(p),(C2O4)(q)](2p-2q) species were: log beta(11) = 6.31 +/- 0.02, log beta(12) = 11.21 +/- 0.07, log beta(13) = 13.8 +/- 0.04, log beta(23) = 18.5 +/- 0.2, log beta(25) = 28.5 +/- 0.1 (I = 3.0 M NaClO4; 25 degreesC). The equilibrium constants were extrapolated to infinite dilution by applying specific ion interaction theory (SIT) and are the following: log beta(11)(0) = 7.41 +/- 0.01, log beta(12)(0) = 11.80 +/- 0.02, log beta(13) (0) = 13.96 +/- 0.07. Formation of polynuclear [(UO2)(2)(C2O4)(3)](2-) and [(UO(2))(2)(C2O4)(5)](6-) species was proved and confirmed independently by conductometry and vapor pressure osmometry.
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