Decoloration of azo dye by a multi-needle-to-plate high-voltage pulsed corona discharge system in water

The decoloration efficiency of azo dye (Acid Orange 7, AO7) using a multi-needle-to-plate high-voltage pulsed corona discharge system was investigated in this paper. The effect of several parameters, including peak pulse voltage and pulse frequency of the discharge system, initial pH and electrical conductivity of the dye solution, mode of needle electrode distribution and gas flow rate on the decoloration rate of the dye wastewater was reviewed. The results obtained show that the pulsed discharge system with a multi-needle-to-plate electrode could dispose azo dye wastewater efficiently. The decoloration rate increased with an increase in applied peak pulse voltage and pulse frequency. Decoloration was more efficient in the acidic solution, and the decoloration rate displayed no marked change under solutions of differing electrical conductivity. For the case in which we example the effect of gas flow rate on the decoloration efficiency of Acid Orange solution, we found that better decoloration efficiency occurred using the seven-needle-to-plate discharge system, which had more discharge anodes. (c) 2005 Elsevier B.V. All rights reserved.