CL-TBP萃淋树脂分离-分光光度法连续测定微量铀和钍  

Continuous Spectrophotometry Determination of Trace Uranium and Thorium Separated by CL-TBP Levextrel Resin

作　　者：周京霞[1] 游建南[1] 

机构地区：[1]核工业北京化工冶金研究院,北京101149

出　　处：《湿法冶金》2001年第4期204-212,共9页Hydrometallurgy of China

摘　　要：研究了在铀水冶工艺中 ,以CLTBP萃淋树脂分离连续分光光度法测定微量铀和钍的方法及其应用。在低温下 ,用混合铵盐熔矿 ,然后用 1mol/L硝酸溶解 ,在 1mol/LHNO3 1.2 5mol/LNH4 NO3 体系中 ,以CLTBP萃淋树脂选择性吸附铀和钍。对吸附在树脂上的铀、钍 ,先用 4mol/L盐酸淋洗钍 ,再用水淋洗铀 ,之后以偶氮胂M作显色剂 ,对淋洗液中的钍和铀进行连续分光光度测定。在 pH =2 .0的一氯乙酸 醋酸铵缓冲介质中 ,铀与偶氮胂M形成紫红色配合物 ,该配合物在波长 6 45nm处有最大吸收 ,表观摩尔吸光系数ε64 5nm=4.8× 10 4 L·mol-1·cm-1。在 4mol/L盐酸溶液中 ,钍与偶氮胂M形成紫红色配合物 ,此配合物在波长 6 6 5nm处有最大吸收 ,表观摩尔吸光系数ε665nm=9.6 7× 10 4 L·mol-1·cm-1。本法可用于测定矿石中 0 .0 0 2 %～0 .5 0 0 %的铀和钍 ,溶液中 0 .0 1～ 1.5mg/L的铀和 0 .0 11.0mg/L的钍。该方法测定铀的精密度为± 6 .7%,标准加入回收率为 97.4%～ 110 .3%;测定钍的精密度为± 6 .2 %,标准加入回收率为 97.8%～ 10 4.4%。对实际样品进行测定 ,结果令人满意。Continuous spectrophotometry determination of trace uranium and thorium separated by CL-TBP levertrel resin has been developed.The ore samples are fused with mixed ammonium-salts,the fused samples is dissolved in 1 mol/L nitric acid. In 1 mol/L HNO 3-1.25 mol/L NH 4NO 3 medium,the uranium and thorium are selectively absorbed on CL-TBP levextrel resin,and separated from other ions.Thorium and uranium on the resin are eluted by 4mol/L HCl and water,respectively.Arsenazo M as color reagent of the uranium and thorium,trace uranium and thorium can be determined by continuous spectrophotometry.In chloroacetic acid-ammonium acetate buffer medium of pH2.0,the U(VI) is combined with arsenazo M into red-violet complex which maximum absorptive peak is at 645nm,and apparent molar absorbance coefficient is 4.8×10 4L·mol -1 ·cm -1 ·In 4 mol/L HCl medium,the Th(IV) is combined with arsenazo M into red-violet complex which maximum absorptive peak is at 665nm, and apparent molar absorbance coeffocient is 9.67×10 4L·mol -1 ·cm -1 .The method has been used to determine U(VI)and Th(IV) in ore and solution samples,the range of determination is 0.005%～0.500% and 0.01～1.5 mg/L(U) and 0.01~1.0 mg/L(Th),respectively,the relative standard deviation is less than ±10%. Recovery of U(VI) and Th(Ⅳ) is 97.4%～100.3% and 97.8%～104.4% respectively.The method is simple and rapid.The results are satisfactory.

关 键 词：铵盐熔矿 树脂分离 偶氮胂M 分光光度法 铀 钍 测定 

分 类 号：X830.2[环境科学与工程—环境工程]