GB/T 2432-1981 Determination of Tetraethyl Lead in Gasoline (Complexometric Titration) GB/T2432-1981 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Deteraimatloa of tetraethyl tendcontent in gasoline
(Complexometric titration)
Gasoline---Deteraimatloa of tetraethyl tendcontent =Corm plexometrfc titretloiThis method is applicable to the determination of tetraethyl lead content in gasoline. 1 Method Summary
GB 2432-41
1888)
This method uses boiling hydrochloric acid to decompose tetraethyl lead in gasoline to generate lead chloride. Then add the precipitated disodium ethylenediaminetetraacetic acid standard solution to form a complex with lead ions. The precipitated disodium ethylenediaminetetraacetic acid standard solution is titrated with zinc oxide standard solution. It is expressed as grams of tetraethyl lead in 1 liter of gasoline.
2 Instruments
2.1, burette: 25 ml.
2.2 Pipette: 25 and 50 ml.
Conical flask with stopper, 500 ml.
Volume sizing: 50 and 100 ml.
Thermometer: 0-100°C, graduated in 1. 2.6
Petroleum density meter: 0.710-0,770 g/ml. Volumetric flask: 1000 liters.
Electric hot plate or sealed electric: 300 watts.
Condenser: Five-ball with ground mouth to match the conical flask. 8 Reagents
3.1 Hydrochloric acid. Analytical grade, make into 6N hydrochloric acid aqueous solution. 3.2 Nitrogen water: Analytical grade.
3.3 Methylenetetramine: Analytical grade.
a.4 Zinc fluoride: analytical grade or pure zinc particles (pure) 3.6 Disodium ethylenediaminetetraacetate: analytical grade, prepared into 0.02M ethylenediaminetetraacetic acid standard solution. *.6 Xylenol orange indicator: Prepare a 0.5% aqueous solution (valid for one month). 3.4 Preparation 4.1: Preparation and calibration of 0.02M zinc chloride standard solution: 4.1.1 Weigh 1.628 g of zinc oxide that has been burned to a constant weight at 800°C, and weigh to 0:0002 g. Add 20 liters of 6N hydrochloric acid aqueous solution and 25 ml of distilled water to dissolve it, then transfer it to a 1000-liter volumetric flask and dilute it to the mark with distilled water. Mix well. The molar concentration of the zinc chloride standard solution is calculated according to formula (1): M
State Administration of Standards 1981-02-18 Issued G
1881-07-01 Implementation
- Weight of zinc chloride, grams,
In the formula, G
- grams of zinc oxide per gram molecule.
GB 2442.--81
4.1.2 Treat pure zinc particles with 6N hydrochloric acid aqueous solution, remove surface oxides, wash with distilled water several times, dry at 1°C, weigh 1.3 g, accurate to 0.0002 g. Dissolve with 20 ml N hydrochloric acid aqueous solution, then transfer to a 1.000 ml volumetric flask, dilute to the mark with distilled water, and mix well.
The molar mass M of the chlorothiazide standard solution is calculated according to formula (2): M2 =
Where: G is the weight of zinc particles, g
65.38 is the number of grams of zinc per gram molecule.
4.2 Preparation and calibration of 0.02M disodium ethylenediaminetetraacetic acid standard solution 1... (2)
4.2.1 Preparation Weigh 8 g of disodium ethylenediaminetetraacetate, dissolve in 1000 ml of distilled water and mix well. 4.2.2 Calibration: Accurately take 25 ml of disodium ethylenediaminetetraacetate standard solution in a conical flask, add 5-6 drops of 0.5% xylenol orange aqueous solution, adjust the solution to pink with ammonia water, and then adjust it to bright yellow with 6N hydrochloric acid aqueous solution, then add 0.5 ml of 6N hydrochloric acid aqueous solution, add 1.5-2.0 g of tetramethylenetetramine, and then titrate with 0.02M zinc chloride standard solution until the solution changes from yellow to pink, which is the end point.
The molar concentration of disodium ethylenediaminetetraacetate standard solution M; Calculate according to formula (3): MV.
The molar concentration of zinc monoxide standard solution; Where: M-
The volume of chlorsulfuron standard solution consumed during titration, milliliters; V
25--The volume of disodium ethylenediaminetetraacetic acid standard solution measured, milliliters. (3)
Each calibration shall be carried out at least three times. The difference between the results of each measurement shall not exceed 0.2% of the arithmetic mean, otherwise it must be discarded. (maximum value-minimum value×100<0.2%)
Lang;
Average value
Take the arithmetic mean of at least three titration results as the molar concentration of sodium ethylenediaminetetraacetic acid standard solution. 5 Test steps
5.1 In a clean stoppered conical flask, use a pipette to inject 50 ml of the sample, add 3 ml of hydrochloric acid, install a reflux condenser, place it on an electric hot plate or a closed electric furnace for heating, and extract. Record the time when the mixed solution in the stoppered conical flask starts to boil, and stop heating after 25 minutes. Rinse the condenser and the inner wall of the stoppered conical flask with 40-50 ml of distilled water and cool to 25-30°C in cold water. 5.2 In the cooled extract, add 25 ml of 0.02M disodium ethylenediaminetetraacetate standard solution and 5-6 drops of 0.5% cresol orange aqueous solution accurately. At this time, the extract is yellow. Then use hydrogen water to adjust the extract to pink, and then use 6N hydrochloric acid aqueous solution to adjust it to yellow. Then continue to add 0.5 ml of 6N hydrochloric acid aqueous solution, and then add 1.5-2 grams of hexamethylenetetramine. Immediately titrate with 0.02M zinc nitride standard solution. The end point is when the extract changes from yellow to pink. Note: "The heating extraction should be carried out in a ventilated room or a rubber hose with a cork plug should be connected to the end of the cold pipe; the lower end of the rubber tube should be inserted into a buffer gas bottle, and the rubber drawn from the buffer bottle should be temporarily put into a bottle filtered by a sodium hydroxide tower. 6 Calculation of the tetraethyl lead content X in the sample, expressed as the number of grams of tetraethyl lead in the sample, according to formula (4): X
Mi-V, -M,-Yr
× 323.2**
Where V,——the volume of the disodium ethylenediaminetetraacetic acid standard solution, set liters, (4)
GB-242--81
M,——Molar concentration of disodium ethylenediaminetetraacetic acid standard solution V Volume of zinc chloride standard solution consumed during titration, ml M——Molar concentration of zinc chloride standard solution V,——Volume of sample, ml
β——Density of sample at test temperature, g/ml; 323.2-——Molecular weight of tetraethyl lead.
7Precision
The difference between two repeated determination results should not exceed the following values: Tetraethyl lead content in 1 kg gasoline, g
Less than or equal to 1.5||t t||Greater than 1.5
Report
Allowable difference
3% of the smaller result
1.5% of the smaller result
Take the arithmetic mean of the two repeated results as the measurement result. Additional remarks:
This standard is proposed by the Ministry of Petroleum Industry of the People's Republic of China. This standard is drafted by Lanzhou Refinery. bzxz.net
From the date of implementation of this standard, the former Ministry of Petrochemical Industry Standard SY2106-78 Determination of Tetraethyl Lead Content in Gasoline (Complexometric Titration) will be invalidated.
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