盐析剂——氯化钠存在下稀土含量的准确测定  

Accurate Measurement of Rare Earth in Presence of Salting-Out Agent——NaCl

作　　者：杜若冰[1] 张燕辉[1] 陆人杰[1] 张婷[1] 马恒励[1] 肖吉昌[1] 

机构地区：[1]中国科学院上海有机化学研究所有机氟化学重点实验室,上海200032

出　　处：《中国稀土学报》2014年第3期370-376,共7页Journal of the Chinese Society of Rare Earths

基　　金：国家973计划项目(2012CBA01200)资助

摘　　要：分光光度法（Spectrophotometry）和电感耦合等离子体发射光谱法（ICP-AES）是常用的测定单一稀土含量的方法。但是萃取稀土过程中通常会加入盐析剂NaCl,萃余水相中大量钠离子所产生的光谱背景严重干扰了稀土含量的测定。考察了NaCl对稀土含量测定的影响,实验结果表明：在基体不匹配的情况下,只有当钠盐浓度低于0.08 mol·L^-1时,分光光度法可以准确测定萃余液中单一轻稀土（La,Ce,Pr,Nd）及中稀土（Sm,Eu,Gd）的含量,但不能准确测定重稀土的含量;而使用ICP-AES法,在NaCl浓度为0.001～1.0 mol·L^-1条件下无法准确测定稀土含量。因此,实验室宜采用分光光度法在基体不匹配的条件下测定轻、中稀土含量,重稀土在基体匹配的条件下用电感耦合等离子体发射光谱法测定。Salting-out agents,such as NaCl,were often used in solvent extraction in order to adjust distribution ra-tio. However,the high-concentration salting-out agent and the low-concentration rare earth in extraction phase create extraordinary difficulties to the accurate measurement of the concentration of rare earths due to the serious spectrum interference of salting-out agent itself. The spectrophotometry and ICP-AES were employed as simple and effective methods for the measurement of rare earths. Nevertheless,both methods were easily affected by the saltingout agent in solvent extraction. The influence of NaCl on the spectrophotometry and ICP-AES measurements was investigated in detail. The experiments showed that the accurate measurement of the rare earth was realized through the combination of spectrophotometry and ICP-AES in the presence of NaCl. For the measurement of the light（ La, Ce,Pr,Nd） and middle（ Sm,Eu,Gd） rare earths,their concentration could be accurately measured by spectrophotometry when the concentration of NaCl was lower than 0. 08 mol·L^-1 without matrix-matched. The measured value was lower than the real concentration when the concentration of NaCl was higher than 0. 08 mol·L^-1 without matrix-matched. It was found that in the case of measurement of the heavy rare earths,matrix-matched condition was necessary for both spectrophotometry and ICP-AES methods. The optical method for the measurement of the light（ La,Ce,Pr,Nd） and middle（ Sm,Eu,Gd） rare earths is that the concentration of sample is diluted to less than 0. 08 mol·L^-1 and measured by spectrophotometry method. For the measurement of heavy rare earths,ICPAES method is recommended under matrix-matched condition.

关 键 词：盐析剂 氯化钠 分光光度法 电感耦合等离子体发射光谱法 稀土萃余液 

分 类 号：O652.1[理学—分析化学]