Tangshan Baifeng Iron & Steel Co., Ltd. has two hot-dip galvanizing plants: Shengtai galvanizing plant and Lifeng galvanizing plant. Mainly engaged in galvanized angle steel, galvanized channel steel, galvanized flat steel, galvanized round steel, galvanized square tube and other galvanized profiles and various types of black products.
The degreasing solution is usually analyzed by titration. The degreasing solution is generally prepared by sodium hydroxide (caustic soda), sodium carbonate, trisodium phosphate and sodium metasilicate (water glass), among which several or all of them are used for the purpose of detecting the solution. The content of these ingredients is convenient for dynamic control in production, and it is convenient to adjust the application in time. Several methods for detecting and analyzing parts are listed below.
2. Detection of sodium hydroxide, sodium carbonate and sodium phosphate degreasing solution
(1) Method points.
Phosphoric acid is a ternary weak acid, sodium phosphate is similar to sodium carbonate, and two cases can occur with a strong acid titration. Therefore, the detection and analysis of a mixture of sodium hydroxide, sodium carbonate, and sodium phosphate can be carried out by a method similar to titration of a mixture of sodium hydroxide and sodium carbonate.
1 titration with sulfuric acid until the phenolphthalein indicator changes from red to colorless;
2 The 1 titrated solution was boiled to remove carbon dioxide, and then returned to the phenolphthalein indicator with alkali to change from colorless to red.
(2) Reagents.
Methyl orange indicator (0.10%), phenolphthalein indicator (1.OO%), standard sulfuric acid solution, standard sodium hydroxide solution
40 g of sodium hydroxide was weighed and dissolved in a hard flask in cold boiling water. After the solution was clarified and cooled, it was diluted to 1.00 L with cold boiling water.
(3) Analysis steps.
Pipette 5 mL of the test solution into a 300 mL Erlenmeyer flask, dilute to 150 mL with water, add 2 drops of methyl orange indicator, and titrate with a standard sulfuric acid solution to the end of red. The solution was boiled to remove carbon dioxide, and after cooling, a few drops of the phenolphthalein indicator were added and titrated to a red color with a standard sodium hydroxide solution.
Pipette another 5 mL of the test solution into a 300 ml Erlenmeyer flask with a pipette and dilute to 150 mL with water. Add 2~3 drops of phenolphthalein indicator and slowly titrate with standard sulfuric acid solution until the red color disappears as the end point under constant stirring. Note that the titration speed should not be too fast, so as to avoid the acidity of the local solution is too high, so that the sodium carbonate directly generates carbon dioxide and is lost.
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