Electro Fenton

Oturan M A, J Peiroten, P Chartin, AJ Acher (2000) Complete destruction of p-nitrophenol in aqueous medium by electro-Fenton method. Environ Sci Technol 34 3474-3479. 

Brillas E, Casado J (2002) Aniline degradation by electro-Fenton and peroxi-coagulation processes using a flow reactor for waste water treatment. Chemosphere 47(3) 241-248... 

Rosales E, Pazos M, Longo MA. Sanroman, MA. Influence of Operational Parameters on Electro-Fenton Degradation of Organic Pollutants from Soil. Journal of Environmental Science and Health. Part A 2009 44 1104-1111. 

Figure 21 Scheme of the pilot flow reactor for the treatment of 10-75 L of waste-waters by the Electro-Fenton and Peroxi-coagulation processes. (From Ref. 143.)... 

Figure 22 TOC removal vs. electrolysis time for 100 mL of a 178-ppm 4-chlorophenol solution in 0.05 M Na2S04 at pH 3.5 and at 25°C, using a 3.1-cm2 ODC fed with an 02 flow of 20 mL min-1, (a) Anodic oxidation in the presence of electrogenerated H202 with a 10-cm2 Pt anode, (b) Electro-Fenton process with the Pt anode and 1.0 mM Fe2+ in the solution, (c) Photoelectro-Fenton process with the Pt anode, 1.0 mM Fe2 +, and UVA irradiation, (d) Peroxi-coagulation process with a 10-cm2 Fe anode. The applied current is 100 mA. (From Ref. 140.)...

Figure 23 Proposed reaction pathway for the mineralization of 2,4-D at pH 3 by anodic oxidation, anodic oxidation in the presence of electrogenerated H202, and Electro-Fenton and Photoelectro-Fenton processes. (From Ref. 149.)...

Oturan MA, Pinson J, Oturan N, Deprez D. Hydroxylation of aromatic drugs by the electro-Fenton method. Formation and identification of the metabolites of riluzole. New J Chem 1999 23 793-794. 

Brillas E, Sauleda R, Casado J. Degradation of 4-chlorophenol by anodic oxidation, Electro-Fenton, Photoelectro-Fenton and Peroxi-coagulation processes. J Electrochem Soc 1998 145 759-765. 

Casado J. Advanced oxidation of organic pollutants in waters. The Electro-Fenton and Helielectro-Fenton processes. EUCHEM 2000 Conference Organic Electrochemistry in the New Century, Tomar, Portugal, 2000. 

Brillas E, Mur E, Sauleda R, Sanchez L, Peral J, Domenech X, Casado J. Aniline mineralization by AOPs anodic oxidation, photocatalysis, electro-Fenton and photoelectro-Fenton processes. Appl Catal B Environ 1998 16 31-42. 

Chou S, Huang YH, Lee SN, Huang GH, Huang C. Treatment of high strength hexamine-containing wastewater by Electro-Fenton method. Water Res 1999 33 751-759. 

Huang YH, Chou S, Perng MG, Huang GH, Cheng SS. Case study on the bioeffluent of petrochemical wastewater by Electro-Fenton method. Water Sci Technol 1999 39 145-149. 

Savinova ER, Kuzmin AO, Frusteri F, Parmaliana A, Parmon VN. Partial oxidation of ethane in a three-phase Electro-Fenton system. In Parmaliana A, ed. Natural Gas Conversion Y. Studies in Surface Science and Catalysis 1998 119 429 134. 

Brillas, E., Boye, B., Sires, I., Garrido, J.A., Rodriguez, R.M., Arias, C., Cabot, P.-L. and Comninellis, Ch. (2004) Electrochemical destmction of chlorophenoxy herbicides by anodic oxidation and electro-Fenton using a boron-doped diamond electrode. Electrochim. Acta 49, 4487 1496. 

The effectiveness of OH radicals in the oxidative decolourisation of various dyes has been also assessed by Flox et al. (2006b), who obtained the complete mineralization of the dye by electro-Fenton and photoelectro-Fenton processes using an undivided cell with a Pt or BDD anode. 

Zhang, H., D. Zhang, and J. Zhou (2006). Removal of COD from landfiU leachate by electro-Fenton method. J. Hazard. Mater. 135,106-111. 

Fig. 19.4 Concentration of accumulated H202 vs. time during the electrolysis of 100 cm3 of a 0.05 M Na2S04 + H2S04 solution of pH 3.0 at 25°C in the Pt/02 cell of Fig. 19.3. (a, b, e) Without Pe2+ (anodic oxidation with electrogenerated H202), (c) with 1 mM Fe2+ (electro-Fenton conditions), (d) in the presence of 1 mM Fe2+ and under 6-W UVA irradiation (photoelectro-Fenton conditions). Applied current (a) 450, (b, c, d) 300,(e) 100 mA (Brillas et al. 2000)...

In an undivided electrolytic cell, the electro-Fenton process leads to the destruction of organics contained in wastewaters by simultaneous oxidation with OH formed at the anode surface from reaction (19.9) and in the medium from Fenton s reaction (19.12). Parallel slower reaction of pollutants with weaker oxidants such as H202, H02, S20g2-, and O3 formed from reactions (19.1), (19.4), (19.10), and (19.11), respectively, is also possible. In addition, final carboxylic acids can form complexes with iron ions that are difficult to be oxidized by OH. We will see the notable influence of the anode material (Pt or BDD) on the degradation of these compounds in further sections. 

Some papers (Brillas et al., 2004a Sires et al. 2006) have explored the effect of Cu2+ as co-catalyst in the electro-Fenton treatment of organics. The Cu2+/Cu+ system is also catalytic (Sharma and Millero 1988 Gallard et al. 1999) involving the reduction of Cu2+ to Cu+ with HO2 by reaction (19.21) and/or with organic radicals R by reaction (19.22)... 

An enhancement of the oxidation power of the electro-Fenton process with both Fe2+ and Cu2+ as catalysts should then be expected due to the additional generation of OH from reaction (19.23), but a more significant effect on the oxidation of final aliphatic acids has been found by the easier oxidation of their complexes with Cu2+ than with Fe3+, as described below. 

The photoelectro-Fenton method involves the simultaneous irradiation of the wastewater with UVA light while it is degraded by electro-Fenton in an undivided cell. UVA irradiation favors the regeneration of Fe2+ from additional photoreduction of Fe (OH)2+, which is the predominant Fe3+ species in acid medium (Sun... 

Electro-Fenton Degradation of Organics Using a Divided Cell... 

This section is devoted to discuss the main results obtained for the treatment of organics in wastewaters by electro-Fenton using a divided cell usually with a cationic membrane (e.g., of Nation) to separate the anolyte and catholyte. Although the anode reactions do not affect the degradation of pollutants under these conditions, it is interesting to know the characteristics of their homogeneous oxidation with OH when this radical is uniquely formed in the medium from Fenton s reaction (19.12). 

The electro-Fenton method (or EFR) was initially used for synthetic purposes considering the hydroxylation of aromatics in the cathodic compartment of a divided cell. Thus, the production of phenol from benzene (Tomat and Vecchi 1971 Tzedakis et al. 1989), (methyl)benzaldehydes and (methyl)benzyl alcohols from toluene or polymethylbenzenes (Tomat and Rigo 1976,1979,1984,1985) by adding Fe3+ to generate Fe2+ via reaction (19.13), as well as benzaldehyde and cresol isomers from toluene or acetophenone and ethylphenol isomers from ethylbenzene (Matsue et al. 1981) with direct addition of Fe2+, have been described. Further studies have reported the polyhydroxylation of salicylic acid (Oturan et al. 1992)... 

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