System and method for monitoring concentration of nitrogen pentoxide and nitric acid in atmosphere on line

Abstract

The invention provides a system and a method for monitoring the concentration of nitrogen pentoxide and nitric acid in atmosphere on line. The on-line monitoring system comprises an aerosol filtering unit, gas wet type absorbing and converting units and optical absorbing and detecting units, wherein the inlet end of the aerosol filtering unit is communicated with the atmosphere to be detected and is used for removing particulate matters from the gas; the outlet end of the aerosol filtering unit is divided into two paths which are connected with a first gas wet type absorbing and converting unit and a second gas wet type absorbing and converting unit and is used for absorbing nitrogen compounds in the gas by an acidic absorbing solution to form a nitrate solution and further converting into nitrite; the front end of the first gas wet type absorbing and converting unit is provided with a NO gas source and converts N2O5, which is introduced into the gas, into NO2; the rear ends of the two gas wet type absorbing and converting units are connected with a first optical absorbing and detecting unit and a second optical absorbing and detecting unit correspondingly to convert the nitrite into an ultraviolet-visible absorbent material and perform optical detection; the first optical absorbing and detecting unit obtains the nitric acid concentration of the N2O5-removed atmosphere; and the second optical absorbing and detecting unit obtains the sum of the nitric acid concentration and the N2O5 concentration of the atmosphere.

Description

technical field [0001] The invention relates to the field of atmospheric environment quality monitoring, in particular to an online monitoring system and method for the concentration of dinitrogen pentoxide and nitric acid in the atmosphere. Background technique [0002] Dinitrogen pentoxide (N 2 o 5 ) as the most important atmospheric oxidant in the nocturnal chemical process of the atmosphere has a significant impact on the level of oxidant in the troposphere and the formation of secondary aerosols. The heterogeneous reaction of dinitrogen pentoxide is NO at high latitudes in winter x The main removal pathway, in addition, can also affect the global O 3 However, due to its low concentration (1pptv-1ppbv), high reactivity, and easy pyrolysis, it is very difficult to detect in the atmosphere. nitric acid (HNO 3 ) is an important oxidation product of nitrogen oxides in the atmosphere, which can be generated by free radical reactions, and can also be produced by the hydro...

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Problems solved by technology

The heterogeneous reaction of dinitrogen pentoxide is NO at high latitudes in winter x The main removal pathway, in addition, can also affect the global O 3 and OH concentration, but due to its low concentration (1pptv-1ppbv), high reactivity, and easy pyrolysis, it is very difficult to detect in the atmosphere

my country's existing online monitoring technology for nitrogen pentoxide and nitric acid in the atmosphere is still very lacking

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