Interaction of UO22+ with sodium dodecyl sulfonate micelles based on fluorescence data
The interaction between the U(VI) and a sodium dodecyl sulfonate (SDS) micelle was studied for intensity and emission lifetime. The measurements of the uranyl ion were done in a 1M H3PO4 medium. The self quenching rate constant (ksq) shows a larger value in micellar than in a SDS monomeric solution. This fact should be interpreted by micelles favoring the localized concentration of UO22+ species. Dynamic and static quenching was observed in the interaction between uranyl ion and the surfactant monomer before the induced critical micelle concentration (icmc) (1 mM) yielding a value of KD = (134±2) . 10M-1 and KS= (16±2) . 102M-1 for the dynamic and static quenching constant, respectively. A quantitative description of the binding was obtained by monitoring the emission lifetime of the uranyl excited state as a function of the surfactant concentration (titration curve), assuming that the observed lifetime is related to a weighted fraction of rate constants for the bound and unbound species.
KeywordsSurfactant Uranyl Critical Micelle Concentration H3PO4 Weighted Fraction
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