نوع مقاله : مقاله پژوهشی
نویسنده
استادیار، دانشگاه صنعتی مالک اشتر،تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
Differential absorption optical spectroscopy is a method to determine the concentration of gaseous pollutants in the environment. This method is widely used to determine the pollutants concentration of a column of atmosphere in a long path of atmosphere. Usually, the absorption spectra of different atmosphere gases overlap in the ultraviolet-visible region. The absorption spectra of SO2 and NO2 gases overlap in the spectral region of 290-310 nm, and the presence of NO2 gas will interfere with the concentration of SO2 gas. Therefore, in this article, an algorithm is used to determine the concentration of SO2 and NO2 gases simultaneously, by the differential optical absorption method. To examine the desired algorithm, a laboratory arrangement has been set up and some spectroscopic tests have been carried out. In the proposed algorithm, absorption spectrum of each gas is divided into two parts: slow and rapid variation spectrum. The rapid variation of the absorbance spectrum has been used to detect the gas and the slow variation has been used to determine the gas concentration. The laboratory set up includes a deuterium-halogen source, a 22 cm single-pass gas cell and a spectrometer. To detect the concentration of two gases, at first, different and known concentrations of NO2 and SO2 gases have been entered into the gas cell separately, and the calibration curve of each gas has been determined. Then, different concentrations of the SO2/NO2 gas combination entered the gas cell and the calibration curve was determined for this gas combination. The concentration of the two gases was determined by using these curves and the desired algorithm with an accuracy of 2%. Also, the detection limit of 72.8 ppm and 140 ppm for SO2 and NO2 gases was obtained, respectively.
کلیدواژهها [English]
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