Author(s): Szpyrkowicz L, Juzzolino C, Kaul SN
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Abstract The results of an experimental study on the destruction of disperse dyes by chemical oxidation using ozone, hypochlorite and Fenton reagent (H2O2 + Fe2+) are compared with the data obtained by electrochemical oxidation. While the results obtained during hypochlorite oxidation were not satisfactory (only 35\% reduction of colour was achieved at a dose of 6 g dm(-3)), ozonation enabled colour to be reduced by up to 90\% (ozone dose 0.5 g dm(-3)). A high decolourisation degree was however accompanied by a low removal (10\% efficiency) of chemical oxygen demand (COD). Trials of electrochemical oxidation proved this process much more efficient. Under the conditions of an acidic pH in 40 min of electrolysis a 79\% elimination of COD was achieved at the Ti/Pt-Ir anode, which proved the best of seven different tested materials. Simultaneously 90\% colour was removed. Indirect oxidation, by means of chlorine-deriving compounds, was the predominating process leading to the pollutants depletion. The best treatment results were obtained with the Fenton process, which under the optimal pH equal to 3 and hydrogen peroxide and ferrous sulphide dose of 600 and 550 mg dm(-3), respectively, resulted in a final effluent being colourless and with the residual COD equal to 100 mg dm(-3).
This article was published in Water Res
and referenced in Journal of Chemical Engineering & Process Technology