GB/T 2564-1981 Determination of acid value and saponification value of montan wax GB/T2564-1981 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Method for determination of acid value and saponification value of montan wax
GB 2564—
This method is applicable to the determination of acid value and saponification value of montan wax. Key points of the method: The montan wax is dissolved in a hot mixed solvent of ethanol and xylene, and then titrated with a standard potassium hydroxide ethanol solution to calculate the acid value. Then add a total of 20 ml of potassium hydroxide ethanol standard solution, including the amount used to determine the acid value, and heat to reflux in a water bath. Then back titrate with a standard hydrochloric acid solution to calculate the saponification value. I. Instruments and reagents
1. Instruments
(1) Erlenmeyer flask extractor (see figure) - consists of two parts: ground-mouth conical flask: 300 ml;
spherical condenser: the end of the conical flask is ground and matched with the conical flask, and the length of the water jacket is about 300 mm; (2) acid burette: 25 ml, graduation 0.1 ml; (3) alkali burette: 25 ml, graduation 0.1 ml; (4) electric constant temperature water bath: constant temperature range 37 ~ 100 ℃, constant temperature control accuracy to ± 2 ℃ ; (5) Fluorescence titration stand
(6) Volumetric tube: 100 ml and 5 ml;www.bzxz.net
(7) Pipette: 25 ml;
(8) Volumetric flask: 1000 ml,
(9) Dropper: 25 ml;
(10) Analytical balance: accurate to 0.0002 g; (11) Electric drying oven: capable of maintaining a temperature of 100~150℃; (12) Desiccator: with desiccant inside.
2. Reagents
(1) 95% ethanol: analytical grade (GB679-80); (2) Xylene: analytical grade (HG3-1011~76); (3) Mixed solvent: 95% ethanol and xylene (1:1 by volume); (4) Hydrochloric acid: analytical grade (GB622-77); (5) Potassium hydroxide: secondary grade (HGB3006-—59); (6) 0.1N potassium hydroxide ethanol standard solution; (7) 0.1N hydrochloric acid standard solution,
(8) Bromothymol blue indicator (HG3-1222-79): Weigh 0.1 g of bromothymol blue indicator, accurate to 0.01 g, and dissolve it in 100 ml of 95% ethanol. It is best to prepare once every two weeks; (9) Phenol crisp indicator (HGB3039-59): 1% ethanol solution; (10) Potassium hydrogen formate (KHC:H,O4): analytical grade (GB1291~77). Issued by the State Administration of Standards
Ministry of Coal Industry of the People's Republic of China
3 Proposed
Implemented on October 1, 1981
Beijing Coal Chemistry Institute of China Coal Research Institute
Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences
GB 256481
Condenser
Erlenmeyer flask extractor
II. Acid value determination steps
3. Accurately weigh 0.3 g (weigh to 0.0002 g) of the mixed and uniform lignite wax sample that has been crushed to 1 mm, put it into a dry 300 ml conical flask, add 60 ml of mixed solvent, connect the spherical condenser according to the diagram, heat and reflux in an electric constant temperature water bath at 86-90°C for 15 minutes (the time starts when the first drop of solvent drips from the end of the condenser), and shake the contents of the flask from time to time. 4. Take out the conical flask, immediately add 1.5 ml of bromothymol blue indicator, and titrate with 0.1N potassium hydroxide ethanol solution on a fluorescent titration table while it is hot until the blue color remains unchanged, and record the amount of potassium hydroxide ethanol solution (read to 0.01 ml). In each titration process, the time from stopping heating the conical flask to completing the titration should not exceed 4 minutes. A blank test should be performed at the same time when measuring wax samples. III. Saponification value determination steps
5. After the acid value is determined, add 0.1N potassium hydroxide ethanol solution to the solution, and add a total of 20 ml, including the amount used for determining the acid value. 6. Heat and reflux in a constant temperature water bath at 86-90℃ for 1 hour and 45 minutes, then add 50 ml of 95% ethanol from the opening of the condenser with a measuring tube, and then flow for 15 minutes.
7. Take out the conical flask, immediately add 1 ml of bromothymol blue indicator, and titrate with 0.1N hydrochloric acid solution on the fluorescent titration table while it is hot until the solution changes from blue to yellow. If blue silk appears again, continue to titrate until the blue silk disappears. Repeat this process many times until no blue silk appears, which is the end point.
IV. Calculation of results
8. The acid value of montan wax is expressed in mg KOH/g and is calculated according to the following formula: Acid value =
Wherein: N
Nx(V-V2)×56.11
-equivalent concentration of potassium hydroxide ethanol solution; 709
GB 2564-81
VI--the volume of potassium hydroxide ethanol solution consumed in titration when determining the wax sample, milliliter; V2--the volume of potassium hydroxide ethanol solution consumed in titration during the blank test, milliliter; G-the weight of the wax sample, g.
9The saponification value of montan wax is expressed in mg KOH/g and is calculated as follows: Saponification value -
Wherein: N --- the equivalent concentration of hydrochloric acid solution; N × (V2--Vl) X56.11
V, --- the volume of hydrochloric acid solution consumed in titration when measuring wax sample, milliliter; V2 --- the volume of hydrochloric acid solution consumed in titration during blank test, milliliter, G --- the weight of wax sample, gram.
10. Take the arithmetic mean of the results of two parallel determinations as the determination result. The result is rounded to an integer. V.
11 The difference between two parallel determinations shall not exceed the following provisions:
Electrochemical value
(absolute)
GB2564-81
1. Preparation of 0.1N potassium hydroxide ethanol standard solution
(1) Preparation method: Weigh 6.9 g potassium hydroxide, dissolve it in 150 ml distilled water, pour it into a 1000 ml volumetric flask, dilute it to 1000 ml with 95% ethanol, and mix well. (2) Calibration: Put potassium hydrogen phthalate in a weighing bottle, open the lid and dry it in a 120℃ drying oven for 2 hours, cover it, take it out, and cool it to room temperature in a desiccator. Then weigh 0.3-0.4 g (accurate to 0.0002 g) and place it in a 250 ml beaker, add 100 ml of distilled water, warm it to dissolve, add 2-3 drops of 1% phenol anhydride indicator, and titrate with the prepared potassium hydroxide ethanol solution until it turns light red, which is the end point. At least four parallel calibrations should be performed at the same time, and the arithmetic mean of the four times with a difference of no more than 0.0010 is taken as the result. (3) Calculate
Where: N—
equivalent concentration of potassium hydroxide ethanol solution;
volume of potassium hydroxide ethanol solution consumed in titration, milliliters; G
weight of potassium hydrogen phthalate, grams;
milligram equivalent of potassium hydrogen phthalate.
2. Preparation of 0.1N hydrochloric acid standard solution
(1) Preparation method: Use a pipette to draw 8.3 ml of hydrochloric acid (specific gravity 1.19), put it into a 1000 ml volumetric flask, and dilute it to 1000 ml with distilled water.
(2) Calibration: Use a pipette to draw 20 ml of the calibrated potassium hydroxide ethanol solution mentioned above, add 2 to 3 drops of 1% phenolphthalein indicator, and titrate with the newly prepared hydrochloric acid solution until the color changes from red to colorless. At least four parallel calibrations are required, and the arithmetic mean of the four times with a difference of no more than 0.0010 is taken as the result. (3) Calculation:
Where: N
equivalent concentration of potassium hydroxide ethanol standard solution; number of milliliters of potassium hydroxide ethanol standard solution taken; number of milliliters of hydrochloric acid solution consumed during calibration N,
- equivalent concentration of prepared hydrochloric acid solution.
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