GB/T 4920-1985 Determination of sulfuric acid mist in sulfuric acid concentrated tail gas - Barium chromate colorimetric method

This standard is applicable to the analysis of sulfuric acid mist in sulfuric acid concentration tail gas of explosives and explosives factories, with a test range of 100 to 30,000 mg/m3. GB/T 4920-1985 Determination of sulfuric acid mist in sulfuric acid concentration tail gas Barium chromate colorimetric method GB/T4920-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of sulphuric acid mist in tail gas of sulphuric acid concentrationprocess-Barium chromate colorimetric methodUDC 628.512
GB4920-85
This standard applies to explosives! Analysis of sulfuric acid mist in tail gas of sulphuric acid concentration, test range 100～30000mg/m. 1 Principle
Sulfate ions react with barium chromate to produce yellow chromate ions, which are determined by colorimetric determination based on the depth of yellow. 2 Instruments
In addition to a general chemical analysis instrument, the following should be available: 2.1 Glass fiber filter without sulfate ions. 2.2 Smoke tester: YC-1 type.
2.2 Spectrophotometer.
3 Reagents
The reagents used in this standard are analytically pure except those specified. 3.1 Chromic acid suspension: weigh 25g barium chromate (superior purity) and mix with 100ml 1N acetic acid and 100ml 0.02N hydrochloric acid. Shake evenly to obtain a turbid solution.
3.2 Calcium chloride-ammonia solution: weigh 1.85g calcium chloride and dissolve it in 500mJ 6N ammonia water (to prevent carbon dioxide from dissolving). 8.8 Sulfuric acid standard solution: accurately weigh 1.777m potassium sulfate (superior purity, constant weight at 800℃) and dissolve it in water, dilute to 1L. 1ml of this solution is equivalent to 1.0mg sulfuric acid. When analyzing, dilute it 10 times with water to make a standard solution of 1ml equivalent to 0.1m sulfuric acid. 4 Operation
Draw the curve on Table 1
Take the sulfuric acid standard solution and prepare it into solutions of different concentrations as shown in Table 1. According to the analysis operation method in 4.2.3, use a 0.5 cm colorimetric III to measure the absorbance (A) at a wavelength of 370 nm on a UV spectrophotometer. Use the absorbance (A) as the ordinate and the sulfuric acid content (mg) as the abscissa to draw a working curve.
National Environmental Protection Agency 1985-01-18 Issued 1985-08-01 Implementation
Standard solution, ml
Water, nl
Vegetable acid content, ng
GB 4920-85
Preparation of working line
1,2 Analysis
4.2.1 Take out the sampling filter cartridge, put it in a 500ml triangular flask, add 100ml distilled water, put a small funnel on the bottle mouth, and heat it on the hot plate until it is almost boiling for about 3 minutes. Let it cool to room temperature, filter the overflow liquid, transfer it to a 1000ml volumetric flask, and wash the triangular flask and filter cartridge residue with water several times, and finally dilute it with water to the scale and mix it evenly. This solution is the sample solution. 4.2.2 When sampling and analyzing the sample solution 1, dilution should be performed according to the different acid contents (no dilution is required for acid contents of 1-2 g/m, dilution is 4 times for 5-10 g/m, and dilution is 10 times for 20-30 g/m). Pipette 1.00 ml of the sample solution into a 100 ml flask, and add 9.00 ml of distilled water (the total volume of the sample solution and distilled water is equal to 10.0 ml to meet the situation when the working curve is prepared). 4.2.3 Add 5 ml of chromic acid suspension, shake thoroughly for 3-5 minutes, then add 1 ml of calcium chloride-ammonia solution, mix, and then add 10 ml of 95% ethanol, shake for 1 minute, cool to room temperature, filter (discard the initial filtrate), take the filtrate and place it in a 0.5 cm colorimetric tube, and perform colorimetry at a wavelength of 370 nm in a UV spectrophotometer. 4.2.4 Take an empty sampling filter cartridge and perform the same operation as 4.2.1-4.2.3 as a blank material. 5 Calculation
S.1 Calculate the sulfuric acid mist content of the sample according to formula (1). Sulfuric acid mist (mg/m3) =
a——total volume of sample solution, ml
volume of sample solution taken during analysis, ml
corresponding amount of sulfuric acid found on the working curve, m converted to sampling volume under standard conditions, L: 5.2
Calculate the ten gas sampling volumes under standard conditions according to the following formula. Vnd = 0.577 × Q
In the formula: ad-
the volume of gas collected under standard conditions, "; Q
the flow meter reading during gas collection, L/min:
n-the time of gas collection, min;
Ba-the atmospheric pressure, mmHg;
P-the pressure gauge reading before the flow meter, mmHgT
the absolute temperature of the flue gas before the flow meter, K.
6 Precautions
6, 1 Preparation of sample solution: Before sampling, the flue gas state parameters should be measured, and the reading of the rotor flow meter for isokinetic sampling should be calculated. When sampling, the sampling tube is inserted into After preheating in the flue for 5 minutes, H starts to take samples at the specified time (usually 3 minutes), and record the rotor flowmeter reading, the pressure before the rotor flowmeter and the flue gas temperature before the rotor flowmeter, which can be used in calculations. GB4920-85www.bzxz.net
6,2 For the specific operation of sampling, please refer to the additional instructions for the preparation of the analysis method of concentrated sulfuric acid pollutants in the explosives industry.
This standard was proposed by the former State Council Environmental Protection Leading Group. This standard was drafted by the Fifth Design Institute of the Ministry of Ordnance Industry. The main drafters of this standard are Zhang Qixin and Wang Lina. This standard is entrusted to the Environmental Protection Department of the Ministry of Ordnance Industry for interpretation.
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