Method for measuring chlorine ion in copper-containing zinc electrolyte sample

Abstract

The invention relates to a method for measuring chlorine ion in a copper-containing zinc electrolyte sample, which comprises the steps as follows: taking 20-50 mL of a zinc electrolyte sample, adding 5mL of 50% sulfuric acid, adding 0.5-1.0 g of zinc powder with purity of 99.999% or 0.2-0.5 g of aluminum powder with purity of 99.999%, stirring until reaction is finished, and diluting to 100 mL with a volumetric flask; carrying out dry filtering, adding 20-50 mL of filtrate to a 300 mL beaker, adding 5-6 mL of nitric acid, adding known amount of excessive silver nitrate (0.05 mol / L) until chlorine ion is precipitated completely, heating for boiling to precipitate and flocculate silver chloride, filtering, washing precipitate, adjusting the volume to 80-100 mL, adding 1 mL of saturated ferric sulfate solution acidified with nitric acid, titrating with 0.01 mol / L potassium thiocyanate solution until the stable red color appears in the solution, namely the end point of titration. According to the invention, the measuring method can be used for rapidly and accurately measuring chlorine ion content in the zinc electrolysis electrolyte without use of an instrument; and high-purity zinc powder or aluminum powder are adopted to remove interference metal ions, and the use amount of the reagents and the operation steps are strictly controlled, therefore, the method can be used for accurately measuring in situ and medium and small-sized laboratories.

Description

technical field [0001] The invention relates to a method for determining chloride ions in a zinc electrolyte, in particular to a method for determining chloride ions in a copper-containing zinc electrolyte sample. Background technique [0002] Chloride ion is an important impurity element in zinc electrolyte. In the process of zinc electrolysis, the presence of chloride ion will corrode the anode, so it must be removed. The determination of chloride ion content in zinc sulfate is particularly important. At present, the determination of Cl in samples in my country - , Most of them use spectrophotometry, turbidimetry, ion chromatography, electrochemical analysis, volumetric method, etc. Different methods have different scopes of use for different samples. 1. Spectrophotometry, 2. Nephelometric method, 3. Ion chromatography, 4. Atomic absorption method, 5. Electrochemical analysis, 6. Volumetric method, etc. The first 5 methods can accurately measure the concentration of chlor...

AI Technical Summary

Problems solved by technology

The biggest disadvantage of this method is that it is difficult to judge the focus; - direct titration of Ag + , until FeSCN appears in the solution 2+ When the red color is red, it means that the focus has been reached, or add a known amount and excess silver nitrate standard solution to the test solution to make Cl - Or after the thiocyanate ion quantitatively generates silver salt precipitation, then add the iron ammonium vitriol indicator, back titrate the remaining silver ion with the thiocyanate standard solution, and use this method to measure Cl - , the end color change is very obvious, but strong oxidation and can make SCN - Oxidation, suboxides of nitrogen and SCN - It can form red NOSCN (nitrosyl thiocyanate), which may cause misjudgment of the end point. Copper salts and mercury salts can interact with SCN - The reaction produces a precipitate which must be eliminated

[0003] One of the most important interfering elements in the determination of chloride ions in zinc electrolyte is copper ions. At present, there is no effective and feasible method for the volumetric determination of chloride ions in zinc electrolyte. Copper ions seriously affect the determination of chloride ions. The concentration seriously affects the service life of the electrode, so it is particularly important to accurately determine the content of chloride ions in the zinc electrolyte