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ISSN : 1738-1894(Print)
ISSN : 2288-5471(Online)
ISSN : 2288-5471(Online)
분광학을 이용한 흄산의 모델 리간드인 2,6-Dihydroxybenzoic acid와 우라늄(VI)의 착물형성 반응에 관한 연구
Spectroscopic Studies on U(VI) Complex with 2,6-Dihydroxybenzoic acid as a Model Ligand of Humic Acid
Abstract
In this study the complex formation reactions between uranium(VI) and 2,6-dihydroxybenzoate (DHB) as a model ligand of humic acid were investigated by using UV-Vis spectrophotometry and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The analysis of the spectrophotometric data, i.e., absorbance changes at the characteristic charge-transfer bands of the U(VI)-DHB complex, indicates that both 1:1 and 1:2 (U(VI):DHB) complexes occur as a result of dual equilibria and their distribution varies in a pH-dependent manner. The stepwise stability constants determined (log K1 and log K2) are 12.4 0.1 and 11.4 0.1. Further, the TRLFS study shows that DHB plays a role as a fluorescence quencher of U(VI) species. The presence of both a dynamic and static quenching process was identified for all U(VI) species examined, i.e., UO2 2+, (UO2)2(OH)2 2+, and (UO2)3(OH)5 +. The fluorescence intensity and lifetimes of each species were measured from the time-resolved spectra at various ligand concentrations, and then analyzed based on Stern-Volmer equations. The static quenching constants (log Ks) obtained are 4.2 0.1, 4.3 0.1, and 4.34 0.08 for UO2 2+, (UO2)2(OH)2 2+, and (UO2)3(OH)5 +, respectively. The results of Stern-Volmer analysis suggest that both mono- and bi-dentate U(VI)-DHB complexes serve as groundstate complexes inducing static quenching.
우라늄(VI), 2,6-다이하이드록시벤조산, 킬레이트 착물, 착물형성상수, 흡수 분광법, 시간분해 레이저유 도형광 분광법, Uranium(VI), 2,6-Dihydroxybenzoic acid, Chelate complex, Complex formation constant, Absorption spectroscopy, TRLFS
Reference
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