离子液体中Ln(Ⅲ)/TBP的配位反应研究

摘要

The complexation reaction of Ln(Ⅲ)/TBP (Ln=Nd ,Eu) in water-saturated 1-butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide (C4mimTf2N)was inves-tigated by absorption spectrophotometry and fluorescence spectroscopy .The results in-dicate that the stability constants (lg β) of the 1:1 complex of Nd(Ⅲ ) with tributyl phosphate (TBP) are 0.68 ± 0.03 ,0.76 ± 0.02 ,0.89 ± 0.03 ,0.97 ± 0.03 ,1.04 ± 0.03 at 10 ,25 ,40 ,55 and 70 ℃ respectively .The best linearity of the plot of ln βvs 100/T indicates that the enthalpy does not change much and is calculated to be 11.52 kJ/mol in the range of 10-70 ℃ . T he stability constant of the 1 : 1 complex of Eu (TBP )3+ is 0.78 ± 0.06 ,which is a little higher than that of the Nd (TBP)3+ complex and can be ascribed to the lanthanides contraction .%应用吸收光谱和荧光光谱法研究了在水饱和的1-丁基-3-甲基咪唑双(三氟甲基磺酰亚胺)盐(C4 mimTf2 N)中Ln(Ⅲ)(Ln=Nd、Eu)与磷酸三丁酯(TBP)的配位反应.结果表明:温度分别为10、25、40、55、70℃时,Nd(TBP)3+的稳定常数lgβ分别为0.68±0.03、0.76±0.02、0.89±0.03、0.97±0.03、1.04±0.03,lnβ对100/T在10~70℃范围内表现出良好的线性关系,配位反应的焓变在该温度范围内基本保持不变,由范特霍夫方程计算得到的Ln(Ⅲ)与TBP配位反应的焓变为11.52 kJ/mol;25℃下,Eu(TBP)3+的稳定常数lgβ为0.78±0.06,略大于Nd(TBP)3+的配位稳定常数,与镧系收缩效应一致.