The sample is burned in a stream of air (or carbon dioxide, oxygen) at 1250-1300 °, and the sulfur in the sulfide and sulfate is dissolved in sulfur dioxide. The hydrogen peroxide is absorbed into the sulfuric acid, and the methyl red primary methyl blue mixed solution is used as an indicator, and titrated with a sodium hydroxide standard solution.
First, the reagent
Hydrogen peroxide absorption solution, 1.25%, take hydrogen peroxide (30%) 25 ml, dilute to 600 ml with water, shake. Add 25 ml of 0.2% methyl red solution (60% ethanol solution) and 5-6 ml of 0.2% methylene blue solution (aqueous solution) and shake well.
Sodium hydroxide standard solution, 0.05N, 2.0 g of sodium hydroxide dissolved in boiled and cooled water, diluted to 1000 ml, and stirred. Store in a lower mouth bottle with a soda asbestos tube.
Calibration, accurately weighed 0.2-0.5 g of reference potassium hydrogen phthalate which had been baked at 120 ° for 1-2 hours, placed in a 250 ml Erlenmeyer flask, and dissolved in 100 ml of warm water. Add 2-3 drops of phenolphthalein indicator agent, titrate with 0.05N sodium hydroxide standard solution until the solution is pink.
N=(W×1000)/(204.2×V)
T=N×16.3
Wherein the weight of potassium hydrogen phthalate (g);
V-titration consumes milliliters of sodium hydroxide standard solution;
The equivalent concentration of the N-sodium hydroxide standard solution;
Titration of sulfur to T-sodium hydroxide standard solution (mg/ml).
Or use a standard sample to calibrate the titer of sulfur in the sodium hydroxide solution.
Second, the analysis procedures
Before the measurement, increase the furnace temperature to 1250 °, pass the air flow, check whether the instrument device leaks, and make a blank test.
A sample of 0.1-0.2 g was weighed and placed in a porcelain boat fired at a high temperature, and 0.2 g of copper oxide was added as a flux.
Weigh 100 ml of hydrogen peroxide absorption solution and place it in the absorption bottle. The porcelain boat containing the sample was pushed into a porcelain tube which had been heated to 1250°, preheated for 30 seconds, and air flow was introduced to make 2-3 bubbles per second. After burning at 1250 ° for 5-10 minutes, the absorption liquid is red, and titrated with a sodium hydroxide standard solution until the solution becomes stable bright green.
%S={[V×(T/1000)]/G}×100
Where the V-titration consumes the milliliters of the sodium hydroxide standard solution;
Titration of sulfur to T-sodium hydroxide standard solution (mg/ml);
G-sample weight (grams).
In strict accordance with ISO 9001:20015 and GB/HG Flanges;
1.Make process card and quality plan
2.Choose the qualified raw material and do incoming test, not allowed
nonconforming material to enter into production process;
3.Producing and testing followed the quality documents
4.Be good at Quality records and product identification to ensure the product
traceability
5.Do the final inspection to ensure 100% of pass.
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