Azo-dyes are a large class of very effective synthetic dyes use for coloring various goods and characterized by a chromophore group by nitrogen-to-nitrogen double bonds. Even though biodegradation is most economical way to treat most organic compounds, it is difficult to biodegrade azo-dyes. However, the chemical oxidation could remove the dyes, and various oxidants have been used for chemical oxidation including H2O2, O3, permanganate, and persulfate(PS). PS could be activated to sulfate radical by thermally, alkaline condition, or transition metals. When the ferrous iron is used as an activator, reaction occurs actively as follows : ?2O82−+ ?e2+→??3++??42−+ ??4−(1). However the sulfate radical is consumed by ferrous, ??4−+??2+→??3++??42−(2), and the reaction rate is much faster than that of reaction (1). Therefore, the control of ferrous amounts in the system is a crucial to achieve high performance of the chemical oxidation. Based on Faraday's law, electrochemical reactions using iron anode can consistently produce the ferrous iron, and then it is expected to activate PS to sulfate radical. In this study, the electrochemical activation of persulfate was investigated to oxidize azo dyes, and the result was compared to that with additional ferrous injection.

Electrochemical activation of persulfate to remove azo-dye

251st National Meeting (2016)

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