Water Science and Technology 2011-01-01

Degradation mechanism of Methyl Orange by electrochemical process on RuO(x)-PdO/Ti electrode.

Lin Du, Jin Wu, Song Qin, Changwei Hu

Index: Water Sci. Technol. 63(7) , 1539-45, (2011)

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Abstract

The electrochemical degradation of Methyl Orange in 0.1 M NaCl solution over RuO(x)-PdO/Ti anode was investigated. Chemical oxygen demand (COD), ion chromatography (IC), Fourier Transform Infrared Spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC-MS) were employed to detect the intermediates formed during the electrochemical degradation. In the present reaction system, Methyl Orange could be effectively degraded. After 1 h treatment, the discoloration could reach 97.9% with COD removal of 57.6%. The results indicated that in the presence of chloride, the electrolysis was able to oxidise the dye with partial mineralisation of carbon, nitrogen and sulfur into CO(2), NO(-)(3) and SO(2-)(4), respectively. After 8 h electrolysis, 62% of sulfur contained in Methyl Orange was transformed to SO(4)(2-), and 17.6% of nitrogen changed to NO(3)(-). The intermediates during electroprocess were detected to be low molecular weight compounds, chlorinated compounds, derivatives of benzene and long chain alkanes. Based on these data, a possible degradation mechanism of Methyl Orange was proposed.