Method for measuring sulfur dioxide

January 05, 2024

1. Principle
The SO2 in the air is absorbed by the potassium tetrachlorohydrin solution and a stable dichlorosulfite complex is formed. The complex is then reacted with formaldehyde and pararosaniline hydrochloride to form a purple complex with a color depth and SO2. The content is proportional to.

2. Measurement points
There are two methods of operation. The amount of phosphoric acid contained in the solution of pararosaniline hydrochloride used in Method 1 was less than that in Method 2, and the pH of the final color solution was 1.6 in soil 0.1 and was reddish-purple. The maximum absorption wavelength was at 548 nm. The reagent blank value was high, and the minimum detection limit was It is 0.75μg/25mL; when the sampling volume is 30L, the minimum detection concentration is 0.025mg/m3.

SO2 is one of the major air pollutants and must be measured for routine monitoring. It originates from the combustion of coal and petroleum fuels, the smelting of sulfur-bearing ores, and the emission of waste gas from the production of chemical products such as sulphuric acid. SO2 is a colorless, water-soluble, pungent odor gas that can enter the trachea through breathing, causing irritation and corrosion to local tissues. It is one of the causes of bronchitis and other diseases, especially when When aerosols such as smoke and dust coexist, damage to the respiratory mucosa can be aggravated.

When measuring, first prepare the required reagents, sample them with an air sampler, and then prepare standard color columns and reagent blank solutions with sodium sulfite standard solution according to the conditions required by method one or method two, and develop color and volume of the sample absorption solution. Finally, using distilled water as the reference at the maximum absorption wavelength, determine the absorbance of standard color columns, reagent blanks, and sample solutions using a spectrophotometer; use standard SO2 content as the abscissa and the corresponding absorbance as the ordinate to draw a standard curve. , And calculate the calculation factor (the reciprocal of the slope of the standard curve), press the formula to measure the SO2 concentration in the air.

Silicon Dioxide B 150