Abstract:
COMPLEX FORMATION OF AMERICIUM(Ⅲ)WITH HUMIC ACIDZhang Yingjie Zhao XinWei Liansheng Lin Zhangji(China Institute of Atomioc Energy,P.O.Box 275(93),Beijing 102413)ABSTRACTThe presence of humic substances in natural waters will modify the migration behavior of actinides in the goesphere due to the strong reaction properties of these ligands with actinides.Therefore,the possible reactions of humic acid with actinides have been studied widely in recent years.The complex formation of Am(Ⅲ) with humic acid is studied with solvent extraction technique.The experiments are performed in the pH range from 4.0 to 8.0 in 0.1 mol/kg NaClO4 solution at ambient temperature.Experimental results show that the complex formation constants of Am(Ⅲ) with humic acid are varied with the variation of pH value in solution. 1∶2 complex is obtained in the experiments and the complex formation constants determined at each pH are:lgβ1=6.56±0.05,lgβ2=10.77±0.31 at pH=4.0. lgβ1=7.94±0.11,lgβ2=11.80±0.21 at pH=5.0. lgβ1=10.74±0.28,lgβ2=12.88±0.49 at pH=6.0. lgβ1=12.85±0.30,lgβ2=14.80±0.62 at pH=7.0. lgβ1=14.88±0.48,lgβ2=15.65±0.69 at pH=8.0,respectively. The dependence of the complex formation constant on pH is:lgβ1=2.16(±0.98)pH-2.34(±0.93),lgβ2=1.28(±1.04)pH+5.52(±1.21),respectively.Keywords 241Am(Ⅲ) Humic acid Extraction Complex HDEHP Stability constant