title: A comparative study on oxidation of disperse dyes by electrochemical process, ozone, hypochlorite and Fenton reagent.
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).
authors.affiliation: Environmental Sciences Department, University of Venice, Italy. lidia@unive.it
authors.forename: L
authors.initials: L
authors.lastname: Szpyrkowicz
authors.forename: C
authors.initials: C
authors.lastname: Juzzolino
authors.forename: S N
authors.initials: SN
authors.lastname: Kaul
mesh_terms: D004396:Coloring Agents / Q000302:isolation & purification*; D004563:Electrochemistry; D006861:Hydrogen Peroxide; D006997:Hypochlorous Acid; D007220:Industrial Waste; D007501:Iron; D010084:Oxidation-Reduction; D010126:Ozone; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D004396:Coloring Agents; C045076:Fenton's reagent; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D010126:Ozone; D006997:Hypochlorous Acid; D006861:Hydrogen Peroxide; D007501:Iron