Degradation of Methyl Orange in Water by Contact Glow Discharge Electrolysis

The degradation of methyl orange in a neutral phosphate buffer solution was investi-gated by means of contact glow discharge electrolysis(CGDE).The methyl oranges were degradedand eventually decomposed into inorganic carbon when CGDE was conducted under the appliedDC voltage of 480 V and current of ca.80 mA.As the intermediate products,some phenolic com-pounds were detected as well as carboxylic acids.Experimental results showed that the oxidationprocess followed the first-order reaction law.Based on the analysis of the ultraviolet(UV)spectraof the solution and the intermediate products from High Pressure Liquid Chromatography-MassSpectrum(HPLC-MS),the reaction pathway was proposed.The attack of hydroxyl radicals wasconsidered to be a key step to start the whole oxidation process.