Long-path FTIR spectroscopic studies of air pollutants in the Danube refinery plant

Abstract

An FTIR spectroscopic study of air samples originating from the residual waste collector and at the ventilation outlet of the wastewater sedimentation tank in the Danube refinery plant has been performed. On the basis of representative samples, the potential capabilities of FTIR spectroscopy have been demonstrated. Methane, benzene, toluene, xylenes, methyl tert-butyl ether and six aliphatic hydrocarbon species have been detected as major components. The dominating hydrocarbon component compound observed was 2-methylbutane. The detection limits established under our experimental conditions (special gas mixture) were below 1 ppm for the majority of compounds. Aliphatic hydrocarbons like n-propane, 2-methylbutane, isobutane (2-methylpropane), 2-methyl-2-butene and 2-methylbutane required much higher levels for detection. For these species there are no strong and non-overlapping spectral features available. Two ways of spectral subtractions in the strongly overlapping regions, 3200–2800 cm⁻¹ and 1500–1300 cm⁻¹, have been discussed in order to analyse long chain aliphatic hydrocarbons. It was established that the sequential auto-subtract method produced more reliable estimations of concentrations of hydrocarbons that the classical least squares procedure.