硫脲析出-EDTA光度滴定法测定含钯合金中钯  

Determination of palladium in palladium-containing alloys by thiourea release-EDTA photometric titration

作　　者：金娅秋 朱武勋 付仕梅 汪原伊 张航波 孙祺 JIN Yaqiu;ZHU Wuxun;FU Shimei;WANG Yuanyi;ZHANG Hangbo;SUN Qi(Yunnan Precious Metals New Materials Holding Group Co.,Ltd.,Sino-Platinum Test Tech(Yun Nan)Co.,Ltd.,Kunming 650106,China)

机构地区：[1]云南省贵金属新材料控股集团股份有限公司,贵研检测科技(云南)有限公司,云南昆明650106

出　　处：《冶金分析》2024年第1期87-92,共6页Metallurgical Analysis

基　　金：云南省贵金属实验室科技计划项目(YPML-2023050237)。

摘　　要：准确测定含钯合金中钯含量对其产品的质量控制、市场交易具有重要的意义。含钯合金中钯的测定常采用丁二肟析出EDTA络合滴定法或丁二肟重量法。但分别存在肉眼判定终点易产生视觉误差或流程较长的问题。将含钯合金溶解后,在样品溶液中加入过量EDTA溶液使其络合钯和共存离子,用锌标准滴定溶液滴定过量的EDTA至溶液颜色由黄色变为红黄色为第1终点,此时滴定体积不参与结果的计算,加入硫脲溶液使硫脲与钯-EDTA中钯络合,析出与钯等量的EDTA,再用锌标准滴定溶液滴定与钯等量的EDTA至溶液颜色由橙黄色变为红黄色为第2终点,采用光度滴定仪将吸光度变化转变为电信号变化来判定滴定终点。据此,建立了光度滴定法测定含钯合金中钯的新方法。将AgPd_(30)、AgPdCu_(20-28)、AuPd_(20)、AuPdNi_(8-22)、PdW_(18)和PdNi_(40)溶解后,按照实验方法对其中的钯进行测定,并加入钯标准溶液进行加标回收试验,结果表明,样品中钯含量(质量分数,下同)的范围为7.83%~81.61%,测定结果的相对标准偏差(RSD,n=7)为0.09%~0.36%,回收率为99.6%~100.3%。分别采用实验方法和行业标准方法YS/T 372.3—2006对PdW_(18)、PdNi_(40)、AgPd_(30)、AgPdCu_(20-28)、AuPd_(20)、AuPdNi_(8-22)中钯平行测定7次,两种方法测定结果基本吻合。The accurate determination of palladium content in palladium-containing alloy is of great significance for the quality control and market trade of products.The determination of palladium in palladium-containing alloy usually adopts dimethylglyoxime EDTA complexometric titration or dimethylglyoxime gravimetry.However,these methods have some problems of visual error easily caused by endpoint judgement with eyes or long procedures in operation.In this study,after dissolving the palladium-containing alloy,excessive EDTA solution was added into sample solution to complex palladium and coexisting ions.The excess EDTA was titrated with zinc standard titration until the solution color changed from yellow to red yellow,i.e.,the first endpoint.At this time,the titration volume did not participate in the calculation of results.Thiourea solution was added to complex palladium in palladium-EDTA.Same amount of EDTA to palladium was released,which was then titrated with zinc standard titration solution until the solution color changed from orange yellow to red yellow,i.e.,the second endpoint.The absorbance change was converted to the electrical signal change using photometric titrimeter to judge the titration endpoint.Consequently,a new method for the determination of palladium in palladium-containing alloy by photometric titration was established.AgPd_(30),AgPdCu_(20-28),AuPd_(20),AuPdNi_(8-22),PdW_(18) and PdNi_(40) were dissolved,and the palladium contents were determined according to the experimental method.Moreover,the palladium standard solution was added for recovery test.The results showed that the palladium content(mass fraction,the same below) in sample was in range of 7.83%-81.61%.The relative standard deviations(RSDs,n=7) of determination results were between 0.09% and 0.36%,the recoveries were between 99.6% and 100.3%.The contents of palladium in PdW_(18),PdNi_(40),AgPd_(30),AgPdCu_(20-28),AuPd_(20) and AuPdNi_(8-22) were determined for 7 times in parallel by the experimental method and industrial standard method(Y

关 键 词：光度滴定法 硫脲析出 EDTA 含钯合金 钯 

分 类 号：O655.2[理学—分析化学] TF836[理学—化学]