Determination of lead in crude tellurium dioxide by Na2EDTA titration method
Received:February 03, 2021  Revised:February 20, 2021
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DOI:10.3969/j.issn.2095-1035.2021.04.015
KeyWord:Titration; Crude tellurium dioxide; Lead
  
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ZHANG Yuan 福建紫金矿冶测试技术有限公司厦门分公司
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Abstract:
      A method for the determination of lead in crude tellurium dioxide was established: the interference of antimony, arsenic and tin is eliminated by hydrobromic acid, lead is precipitated by sulfuric acid, then the content of lead in tellurium dioxide is determined through EDTA complexometric titration method. The sample is dissolved by nitric acid and hydrochloric acid, lead is precipitated by sulfuric acid. The interference of antimony, arsenic and tin is eliminated by hydrobromic acid, other coexisting elements are separated by filtration. Lead sulfate is dissolved in acetic acid sodium acetate buffer solution. The content of lead in the solution was titrated with Na2EDTA solution using xylenol orange as indicator at pH5.0 ~ 6.0. The results indicate that the amount of hydrobromic acid and tartaric acid added shall be 15 ml mL and 10 mL respectively, the precipitation volume shall be about 50 to 60 ml and the precipitation time shall be more than 1 hour. The relative standard deviation (RSD) of the method is 0.10% - 1.13%, and the recovery rate of standard addition is 97.1% - 101.7%. The method meets the requirements of the detection of lead content in crude tellurium dioxide during the production control.
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