6,6'-二(5,6-二乙基-1,2,4-三嗪-3-基)-2,2'-联吡啶萃取分离镅与镧系元素

摘要

The extraction behavior of americium and lanthanides from nitric acid solution was investigated under various conditions, such as contact time, the concentration of C2-BTBP, and the concentration of nitric acid. The results show that the extraction equilibrium of americium is reached in 10 minutes. The distribution ratio of americium increases firstly and then decreases with different concentrations of nitric acid. The distribution ratio of lanthanides is very low in different concentration of nitric acid. On the basis of batch extraction experiments, a 10 stages counter-current flowsheet was set up (6 stages for extraction, 4 stages for scrubbing, ratio of flow AF ! AX ! AS=1 ! 1 ! 0. 5, 1. 0 mol/L HN03 of aqueous feed, and 1. 0 mol/L HNO3 as scrubbing solution). The experiment results show that the extraction efficiency of americium and lanthanides is more than 99. 93% and the concentration of lanthanides is less than 0. 03% , respectively. The decontamination factor for americi-rnum in lanthanides is more than 103. The experimental results indicate that americium can bernseparated from lanthanides by C2-BTBP.%在硝酸介质中,研究了6,6 '-二(5,6-二乙基-1,2,4-三嗪-3-基)-2,2'-联呲啶(6,6'-bis(5,6-diethyl-],2,4-triazin-3-yl)-2,2'-bipyridine,C2-BTBP)/CHCl3体系对镅和镧系元素的萃取行为.重点考察了萃取时间、萃取剂浓度、水相硝酸浓度等因素对C2-BTBP萃取Am的影响.结果表明:C2-BTBP萃取镅时,10 min达到平衡;D(Am)随酸度增大先增大后减小.在考察的酸度范围内,镧系元素的分配比均较小.提出了C2-BTBP/CHCl3体系分离三价锕系与镧系元素的概念流程,并经串级实验验证.萃取剂(C2-BTBP/CHCl3)浓度为0.04 mol/L,料液酸度为1.o mol/L HNO3,洗涤液酸度为1.0 mol/LHNO3,流比为AF∶AX∶ AS=1∶1∶0.5,经6级萃取、4级洗涤后,镅的萃取率为99.93％,Am中Ln的去污因子大于103,Am中镧系元素的含量小于0.03％,可较好的实现镅和镧系元素的分离.