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Extraction behavior of thorium(Ⅳ) and uranium(Ⅵ) from nitric acid(HNO_3) was studied using N,N,N’,N’-tetraoctyldiglycolamide(TODGA) as extractant in different ionic liquids, and isooctane as comparison.Slope analyses with varying HNO_3 concentrations and diluents revealed the extraction mechanism. With increasing length of alkyl chain and HNO_3 concentration, the extraction mechanism of TODGA/IL system changed from cation exchange to neutral complex and/or anion exchange,and the molar ratio between TODGA and metal ions varied gradually from 2:1 to 1:1 for Th(Ⅳ) and 3:1 to 1:1 for U(Ⅵ). The kinetics and thermodynamic studies of Th(Ⅳ)and U(Ⅵ) by the best TODGA/[C_2mim][NTf_2] system showed that the extraction equilibrium was reached within 2 h and extraction reactions were endothermic. Compared to TODGA/isooctane system, TODGA/[C_2mim][NTf_2]system presented higher radiation stability under c-irradiation. Therefore, it would have a promising application in spent fuel reprocessing.
Extraction behavior of thorium (Ⅳ) and uranium (Ⅵ) from nitric acid (HNO_3) was studied using N, N, N ’, N’-tetraoctyldiglycolamide (TODGA) as extractant in different ionic liquids, and isooctane as comparison.Slope analyzes with With increasing length of alkyl chain and HNO 3 concentration, the extraction mechanism of TODGA / IL system changed from cation exchange to neutral complex and / or anion exchange, and the molar ratio between TODGA and metal ions Variations from 2: 1 to 1: 1 for Th (Ⅳ) and 3: 1 to 1: 1 for U (Ⅵ). The kinetics and thermodynamic studies of Th (Ⅳ) and U (Ⅵ) by the best TODGA / [ C_2mim] [NTf_2] system showed that the extraction equilibrium was reached within 2 h and extraction reactions were endothermic. Compared to TODGA / isooctane system, TODGA / [C_2mim] [NTf_2] system presented higher radiation stability under c-irradiation. Therefore, it would have a promising applications in spent fuel reproces sing.