A comparative study on oxidation of disperse dyes by electrochemical process, ozone, hypochlorite and Fenton reagent.

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).

[1]  Yizhong Wang.  Solar photocatalytic degradation of eight commercial dyes in TiO2 suspension , 2000 .

[2]  J. Jones,et al.  Decolorization Of Textile Dye Solutions , 1993 .

[3]  R. Rice,et al.  Handbook of ozone technology and applications , 1982 .

[4]  A. Puig,et al.  Treatment of a wastewater resulting from dyes manufacturing with ozone and chemical coagulation , 1998 .

[5]  Lars Baetz Reutergådh,et al.  Photocatalytic decolourization of reactive azo dye: A comparison between TiO2 and us photocatalysis , 1997 .

[6]  Sheng H. Lin,et al.  Fenton process for treatment of desizing wastewater , 1997 .

[7]  M. Abdo,et al.  Anodic oxidation of a direct dye in an electrochemical reactor , 1987 .

[8]  Shyh-Fang Kang,et al.  Coagulation of textile secondary effluents with Fenton's reagent , 1997 .

[9]  V. Schaller,et al.  Theoretical model for the anodic oxidation of organics on metal oxide electrodes , 1997 .

[10]  J. Gould,et al.  The effect of solute competition on ozonolysis of industrial dyes , 1983 .

[11]  M. Eiteman,et al.  Evaluation of Membrane Filtration and Ozonation Processes for Treatment of Reactive-Dye Wastewater , 1998 .

[12]  W. Kuo,et al.  Decolorizing dye wastewater with Fenton's reagent , 1992 .

[13]  Sheng H. Lin,et al.  Treatment of textile wastewater by chemical methods for reuse , 1997 .

[14]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[15]  X. Verykios,et al.  The effect of operational parameters and TiO2-doping on the photocatalytic degradation of azo-dyes , 1999 .

[16]  L. Szpyrkowicz,et al.  Electrochemical treatment of textile wastewater , 1996 .

[17]  S. Daniele,et al.  Electrochemical oxidation of dyeing baths bearing disperse dyes , 2000 .

[18]  Sheng H. Lin,et al.  Treatment of textile wastewater by electrochemical method , 1994 .

[19]  Shengyu Lin,et al.  Treatment of textile waste effluents by ozonation and chemical coagulation , 1993 .

[20]  Christos Comninellis,et al.  Oxidation of organics by intermediates of water discharge on IrO2 and synthetic diamond anodes , 1999 .

[21]  M. S. Gonçalves,et al.  Photochemical treatment of solutions of azo dyes containing TiO2 , 1999 .

[22]  J. Do,et al.  Decolourization of dye-containing solutions by electrocoagulation , 1994 .