真空蒸馏预富集双十二烷基二硫代乙二酰胺光度法测定微量铂钯

采用真空蒸馏预富集、双十二烷基二硫代乙二酰胺(DDO)光度法测定铅锌试样中的铂和钯。在真空条件下,利用铅、锌、铂、钯在较高温度下蒸汽压的差别进行分离,富集后的铂、钯用DDO分光光度法进行测定,且实现了铅和锌真空密闭回收。针对试样的特点,对真空蒸馏方法理论上的可行性进行研究,并得到优化的试验条件。结果表明:真空度为6 Pa、温度为900℃时,对试样蒸馏2 h,锌和铅可基本脱除,分离富集效果最好。方法已应用于废电路板贵金属冶余物料中铂、钯的分析,铂、钯的回收率分别为93.3%~113.3%、99.2%~107.4%,相对标准偏差小于5.0%(n=6)。

Determination of trace platinum and palladium by vacuum distillation pre-enrichment combined with N, N'-didodecyl dithiooxamide spectrophotometry

Trace platinum and palladium in lead-zinc sample were determined by vacuum distillation pre-enrichment combined with N,N'-didodecyl dithiooxamide (DDO) spectrophotometry. In vacuum, lead, zinc, platinum and palladium were separated at high temperature due to their different vapor pressure. The enriched platinum and palladium were determined sequentially by DDO spectrophotom-etry. Moreover, the recovery of lead and zinc was realized in vacuum. The theoretic feasibility of the vacuum distillation method was studied based on the feature of sample, and the experimental conditions were optimized. The results indicated that zinc and lead could be totally removed at 6 Pa at 900 ℃ with distillation duration of 2 hours, and the separation-enrichment results were the best. This method was applied to the determination of platinum and palladium in noble metal smelting remainder of waste circuit board, resulting in the recoveries of 93.3%-113.3% for platinum and 99.2%-107.4% for palladium. The relative standard deviation (RSD) was less than 5% (n=6).