Mechanisms of Decomposition of Organic Compounds by Water Plasmas at Atmospheric Pressure

Abstract

The decomposition of acetone, methanol, and ethanol by water plasmas at atmospheric pressure has been investigated using a direct current (DC) discharge. At torch powers of 910–1050 W and organic compound concentrations of 1–10 mol %, the decomposition rate of methanol was over 99.99%, while those of acetone and/or ethanol was 96–99%. The concentrations of H2 obtained were 65–71% in the effluent gas and the removal efficiencies of 90–95% for total organic carbon (TOC) were achieved in liquid effluent for any compounds by pyrolysis. Over 50 wt % carbon in acetone or ethanol fed as the plasma supporting gas was transformed into soot, while the soot formation was negligible during methanol decomposition. On the basis of the experimental results, the mechanisms of decomposition of organic compounds in water plasmas were proposed and the mechanism of soot formation was clarified for the first time.