Diagnostics of Organic Compounds Degradation by Optical Emission Spectroscopy

This contribution is focused on the optical emission spectroscopy observations of the DC non-pulsed diaphragm discharge in various water solutions. The emission intensities of the hydroxyl radicals and the atomic lines of some selected elements are investigated. We have also studied the influence of the experimental conditions (for example of the applied high voltage and the discharge power, pH, the solution conductivity etc.) on the emission intensity. The results are proposed for the application in the analytic chemistry. Introduction Discharges generated in liquids have been an object of the intense research during the last years. The processes taking place in such discharges are applied in the fields of water treatment, destruction of various organic pollutants dissolved in water, surface treatment of polymeric fibres and in specific reactions in a liquid phase. The common discharge configurations are point-to plane [Clements et al., 1987; Joshi et al., 1995] and coaxial [Sunka et al., 1999], several experiments were done in a diaphragm (electrode-less) configuration [Kuzhekin et al., 1995]. During almost all of these experiments, a pulsed high voltage in the range of about 10 to 20 kV was used to create the discharge. The present contribution focuses on the diaphragm discharge created using the non-pulsed DC high voltage, that can be about 2 kV only. [Krcma et al., 2002]. Various active species are produced by such discharge (hydroxyl radicals, hydrogen and oxygen radicals, hydrogen peroxide etc.) [Joshi et al., 1995]. These species can take part in the dissociation of organic compounds dissolved in the reaction medium.