pH-metric and thermodynamic studies of rare earth metal chelates
来源期刊：Journal of Rare Earths2009年第3期
论文作者：Alok Vyas R. P. Mathur
文章页码：457 - 460
摘 要：Proton ligand stability constants of hydroxybenzoic acid containing nitro group（2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid） were determined through Irving-Rossoti pH titration technique. The stability constants of rare earth metal chelates containing 2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid as ligands were studied in aqueous medium at different ionic strength（μ=0.01,0.05 and 0.1 mol/L） and temperatures（298,308 and 318± 0.1 K） . The values of stability constant were evaluated through different computational methods like successive approximation,least square treatment,correction term method,and convergence method. The observed value of thermodynamic parameters（△G°,△H° and △S°） favors the complex formation between metal and ligands. The order of stability constant was found to be Pr（Ⅲ） <Nd（Ⅲ） <Sm（Ⅲ） <Tb（Ⅲ） <Ho（Ⅲ） <Er（Ⅲ） as reported by Stagg and Powell.
Alok Vyas，R. P. Mathur
摘 要：Proton ligand stability constants of hydroxybenzoic acid containing nitro group（2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid） were determined through Irving-Rossoti pH titration technique. The stability constants of rare earth metal chelates containing 2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid as ligands were studied in aqueous medium at different ionic strength（μ=0.01,0.05 and 0.1 mol/L） and temperatures（298,308 and 318± 0.1 K） . The values of stability constant were evaluated through different computational methods like successive approximation,least square treatment,correction term method,and convergence method. The observed value of thermodynamic parameters（△G°,△H° and △S°） favors the complex formation between metal and ligands. The order of stability constant was found to be Pr（Ⅲ） <Nd（Ⅲ） <Sm（Ⅲ） <Tb（Ⅲ） <Ho（Ⅲ） <Er（Ⅲ） as reported by Stagg and Powell.
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