Method for analyzing cadmium chloride in acid cyanide-free cadmium plating solution

An analysis method, cyanide cadmium plating technology, applied in chemical method analysis, material analysis by observing the influence of chemical indicators, chemical analysis by titration method, etc., can solve the problem of inability to change color, low measurement results, and discoloration at the titration end point Not sensitive enough to achieve the effect of high precision and accuracy

Active Publication Date: 2016-11-09
GUANGZHOU ULTRA UNION CHEM LTD
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  • Abstract
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Problems solved by technology

[0005] The present invention proposes an analysis method for cadmium chloride in an acidic cyanide-free cadmium plating solution, using ammonium persulfate to destroy complexing agents such as nitrilotriacetic acid in the plating solution under strong acidity and heating conditions, and adding excessive EDTA standard solution Coord...

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Experimental program
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Effect test

Embodiment 1

[0025] Prepare the following reagents:

[0026] Chrome black T indicator: Grind and mix 0.2g of chrome black T with 100g of sodium chloride.

[0027] Sulfuric acid: the volume ratio of 95% to 98% concentrated sulfuric acid to water is 1:9.

[0028] Ammonia water: The volume ratio of 25% to 28% concentrated ammonia water to water is 1:1.

[0029] Ammonium persulfate: solid.

[0030] Ascorbic acid: solid.

[0031] Triethanolamine: The volume ratio of triethanolamine (analytical pure) to water is 1:19.

[0032] EDTA standard solution: 0.05mol / L.

[0033] Zinc sulfate standard solution: 0.05mol / L.

[0034] Take NCC-617 acidic cyanide-free chromium plating solution from the electroplating workshop (references: Guo Chongwu. Development and Research of New Acidic Cyanide-free Cadmium Plating Process [J]. Electroplating and Finishing, 2016, 35 (5): 250-255.), with Pipette 2 mL of the plating solution into six 300 mL Erlenmeyer flasks, add 80 mL of water to dilute, add 10 mL of s...

Embodiment 2

[0039] Prepare the following reagents:

[0040] Chrome black T indicator: Grind and mix 0.2g of chrome black T with 100g of sodium chloride.

[0041] Sulfuric acid: the volume ratio of 95% to 98% concentrated sulfuric acid to water is 1:9.

[0042] Ammonia water: The volume ratio of 25% to 28% concentrated ammonia water to water is 1:1.

[0043] Ammonium persulfate: solid.

[0044] Ascorbic acid: solid.

[0045] Triethanolamine: The volume ratio of triethanolamine (analytical pure) to water is 1:19.

[0046] EDTA standard solution: 0.05mol / L.

[0047] Zinc sulfate standard solution: 0.05mol / L.

[0048]Prepare 1 L of NCC-617 acidic cyanide-free cadmium plating solution developed by Chaobang Chemical Co., Ltd., containing 37.00 g / L of cadmium chloride in the plating solution. Use a pipette to draw 2 mL of the plating solution into a 300 mL Erlenmeyer flask, add 80 mL of water, 10 mL of sulfuric acid water, and 2 g of ammonium persulfate, heat to boiling for 5 min, and cool...

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Abstract

The invention discloses a method for analyzing cadmium chloride in an acid cyanide-free cadmium plating solution. The method includes the steps that a coordination agent in the acid cyanide-free cadmium plating solution is oxidized with ammonium persulfate under the strong acid condition so that cadmium ions can be released from coordination ions; iron ions are masked with ascorbic acid and aluminum ions are masked with triethanolamine under the condition that pH ranges from 9.5 to 10, an excess EDTA standard solution is added to coordinate with cadmium ions, eriochrome black T serves as an indicator, EDTA is subjected to back titration with a zinc sulfate standard solution, and the mass concentration of cadmium chloride in the plating solution is calculated with a minusing method. According to the method, in the testing process, sulfuric acid is added into the tested solution to make the tested solution have strong acidity, and then the coordination agent is completely oxidized with ammonium persulfate under the heating condition, so that interference of the coordination agent with cadmium chloride determination is eliminated. The method is accurate in determination result and superior to an existing method.

Description

technical field [0001] The invention relates to an analysis method for cadmium chloride in an acidic cyanide-free cadmium plating solution. Background technique [0002] Due to the excellent corrosion resistance and softness of cadmium plating, aerospace parts are still prepared with cadmium plating process for protective layer. The traditional cyanide cadmium plating process uses sodium cyanide as a complexing agent, and cyanide is one of the pollutants strictly prohibited by the state. In accordance with the requirements of the National Development and Reform Commission's "Industrial Structure Adjustment Catalog (2011 Revised Edition)", some aerospace companies are replacing traditional cyanide cadmium plating with acidic cyanide-free cadmium plating. [0003] The analysis of cadmium chloride in acidic cyanide-free cadmium plating solution currently adopts EDTA volumetric method [1] , the method uses ammonium persulfate to oxidize the complexing agent in the plating solu...

Claims

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Application Information

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IPC IPC(8): G01N31/16G01N21/79
CPCG01N21/79G01N31/162
Inventor 郭崇武赖奂汶
Owner GUANGZHOU ULTRA UNION CHEM LTD
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