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目的 研究镧 (Ⅲ ) [La(Ⅲ ) ]、钕 (Ⅲ ) [Nd(Ⅲ ) ]、钐 (Ⅲ ) [Sm(Ⅲ ) ]与L—苏糖酸配合物的稳定性。方法 以pH电位滴定法于I=0 .10mol·dm-3 KNO3 ,维持温度为 2 5± 0 .1℃测定配合物的形成常数。结果 La(Ⅲ )、Nd(Ⅲ )、Sm(Ⅲ )与L—苏糖酸配合物的生成常数分别为 :La(Ⅲ ) 2 .6 2 (110 )、5 .2 3(12 0 )和 -4.93(11- 1) ;Nd(Ⅲ ) 2 .88(110 )、5 .47(12 0 )和 - 3.94(11- 1) ;Sm(Ⅲ ) 3.2 4(110 )、5 .71(12 0 )和 - 3.5 7(11- 1)。结论 La(Ⅲ )、Nd(Ⅲ )、Sm(Ⅲ )苏糖酸配合物的稳定性随离子半径的减小而增大 ,与三离子的离子势的大小顺序一致。
Objective To investigate the stability of lanthanum (Ⅲ) [La (Ⅲ)], neodymium (Ⅲ) [Nd (Ⅲ)] and samarium (Ⅲ) [Sm (Ⅲ)] complexes with L-threonate. Methods The formation constants of the complexes were determined by pH potentiometric titration at I = 0. 10mol · dm-3 KNO3 and the temperature was kept at 25 ± 0.1 ℃. Results The formation constants of La (Ⅲ), Nd (Ⅲ) and Sm (Ⅲ) complexes with L-threonate are La (Ⅲ) 2 .6 2 (110), 5.23 (120) and -4.93 (11-1); Nd (III) 2.88 (110), 5.47 (12 0) and -3.94 (11-1); Sm 0) and - 3.5 7 (11-1). Conclusions The stability of La (Ⅲ), Nd (Ⅲ) and Sm (Ⅲ) threonate complexes increases with the decrease of ion radius, which is consistent with the order of ion potential of the three ions.