Bimodal normal distribution model for binding of trivalent europium by soil fulvic acid期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

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Bimodal normal distribution model for binding of trivalent europium by soil fulvic acid

Authors:	H S Shin B H Lee H B Yang S S Yun H Moon

Institution:	(1) Department of Chemistry, Korea Advanced institute of Science and Technology, 373-1 Kusong-dong, Yusong-ku, 305-701 Taejon, (Korea);(2) Korea Atomic Energy Research Institute, P.O. Box 105, 353-606 Taejon, (Korea);(3) Department of Chemistry, Chungnam National University, 305-764 Taejon, (Korea)

Abstract:	Complexation of trivalent europium by a well characterized soil fulvic acid was investigated by equilibrium dialysis titration method (FA]=24 mg·dm^–3, Eu]_t=9.0·10^–7–3.5·10^–6 mol·dm^–3, pH 6.0). The concentrations of the fulvate bound and free europium were measured radiometrically using¹⁵²Eu as a tracer. The experimental results were evaluated using a bimodal normal distribution model and a plot with two overlapping normal distributions was obtained which gave two means logK (µ_I=7.0, _I=1.1; µ_II=4.9, _II=0.5) values for binding of europium by two classes of sites in fulvic acid. A multiligand model was assumed for fulvic acid, based upon the Eu(III) luminescence studies (⁷F₀⁵D₀ excitation) on many organic acids as model ligands.

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