DC Diaphragm Discharge in Water Solutions of Selected Organic Acids

abstract

English

This work concentrates on plasma discharge in water solution of two simple organic acids. Diaphragm discharge configuration is used, when the reactor is divided into two parts by a dielectric barrier with a small orifice. That enables study of processes under both polarities at the same time. The efficiency of the discharge is quantified by the hydrogen peroxide production, determined using UV-VIS spectrometry of H2O2 complex with titanium reagent. Optical emission spectra (OES) were obtained during the discharge to evaluate the differences for two concentrations of the acids and a selected reference solution of NaCl. Formic and acetic acids were chosen. Results show higher hydrogen peroxide production when acids are used in concentration of 1 mmol l-1compared to the reference solution – the values obtained reached 1.57 and 1.29 g/kWh for the formic and acetic acid, respectively, while it was 1.16 g/kWh for the reference solution. On the other hand, addition of acid in concentration of only 0.1 mmol l-1 leads to slight decrease in the hydrogen peroxide content after the experiment under otherwise same conditions. This decrease represents about 10 % of the reference H2O2 production. OES do not show higher intensity of OH radical signal for acid solutions. This indicates different mechanism for hydrogen peroxide concentration rise rather than higher creation rate – it might be due to lower pH of the solutions, since hydrogen peroxide is more stable in acidic conditions.

diaphragm discharge, hydrogen peroxide, pH, organic acid, optical emission spectroscopy

VYHNÁNKOVÁ, E.; HAMMER, M.; REUTER, S.; KRČMA, F.

21. 9. 2014

Greifswald

74

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