J. Environ. Eng. Manage 01/2009; 19:307-314.

ABSTRACT Optimum conditions for generating hydrogen peroxide in Electro-Fenton oxidation in an undivided cell at a carbon cloth cathode were individuated, examining the effect of cathode potential, technique for providing oxygen, pH and concentration of electrolyte. The best conditions are: cathode potential -1 V vs. Ag/AgCl, air sparing 1 L min -1 at the cathode, pH 3.0 in 0.05 M sodium sulphate electrolyte. Capillary electrophoresis was investigated as a potential analytical technique for monitoring electro-Fenton oxidation of chlorinated anilines by determining the inorganic ions produced. The sequential analysis of the six ionic species investigated required less than 1 h on a routine basis. In the electro-Fenton oxidation of chloroanilines, stoichiometric amounts of ammonium and chloride ions were measured after 180-min treatment; no nitrite or nitrate ions were detected. Fe 2+ was continuously regenerated at the cathode and the observed time trends of Fe 2+ and Fe 3+ concentrations showed marked differences in the presence or absence of chloroanilines.

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    ABSTRACT: The degradation of 10-30 l of a 1000 ppm aniline solution in 0.050 M Na2SO4 + H2SO4 at pH 3.0 and 40 degrees C by Electro-Fenton and peroxi-coagulation processes at constant current until 20 A has been studied using a pilot flow reactor in recirculation mode with a filter-press cell containing an anode and an oxygen diffusion cathode, both of 100 cm2 area. H2O2 is produced by the two-electron reduction of O2 at the cathode, being accumulated with a current efficiency between 60% and 80% at the first stages of electrolyses performed with a Ti/Pt anode. In the presence of 1 mM Fe2+, less H2O2 is accumulated, but it is not detected using an Fe anode. The Electro-Fenton process with 1 mM Fe2+ and a Ti/Pt or DSA anode yields an insoluble violet polymer, while the soluble total organic carbon (TOC) is gradually removed, reaching 61% degradation after 2 h at 20 A. In this treatment, pollutants are preferentially oxidized by hydroxyl radicals formed in solution from reaction of Fe2+ with H2O2. The peroxi-coagulation process with an Fe anode has higher degradation power, allowing to remove more than 95% of pollutants at 20 A, since some intermediates coagulate with the Fe(OH)3 precipitate formed. Both advanced electrochemical oxidation processes (AEOPs) show moderate energy costs, which increase with increasing electrolysis time and applied current.
    Chemosphere 05/2002; 47(3):241-8. · 3.50 Impact Factor
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    ABSTRACT: The oxidative efficiency and energy consumption, in the degradation of chloroanilines by anodic oxidation, indirect oxidation with electrogenerated hydrogen peroxide and electro-Fenton have been compared, using a laboratory system driven by a LabVIEW virtual controller. Solutions were oxidized in an undivided cell, where H(2)O(2) was generated electrochemically by reduction of atmospheric oxygen bubbled at a carbon cloth cathode. The electro-Fenton process showed the best degradation power, in terms of efficiency of removal and energy consumption. This process was applied to the purification of a solution obtained by washing a polluted soil. Under laboratory conditions, electro-Fenton removed 75% COD of this wastewater with a specific energy consumption of 0.3kWh per gram of COD, corresponding to 41.8kWhm(-3).
    Chemosphere 07/2006; 64(3):386-92. · 3.50 Impact Factor
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    ABSTRACT: The degrdn. of herbicides 4-chlorophenoxyacetic acid (4-CPA), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aq. medium of pH 3.0 was comparatively studied by anodic oxidn. and electro-Fenton using a B-doped diamond (BDD) anode. All solns. are totally mineralized by electro-Fenton, even at low current, being the process more efficient with 1 mM Fe2+ as catalyst. This is due to the prodn. of large amts. of oxidant hydroxyl radical (OH.bul.) on the BDD surface by H2O oxidn. and from Fenton's reaction between added Fe2+ and H2O2 electrogenerated at the O2-diffusion cathode. The herbicide solns. are also completely depolluted by anodic oxidn. Although a quicker degrdn. is found at the 1st stages of electro-Fenton, similar times are required for achieving overall mineralization in both methods. The decay kinetics of all herbicides always follows a pseudo 1st-order reaction. Reversed-phase chromatog. allows detecting 4-chlorophenol, 4-chloro-o-cresol, 2,4-dichlorophenol and 2,4,5-trichlorophenol as primary arom. intermediates of 4-CPA, MCPA, 2,4-D and 2,4,5-T, resp. Dechlorination of these products gives Cl-, which is slowly oxidized on BDD. Ion-exclusion chromatog. reveals persistent oxalic acid in electro-Fenton by formation of Fe3+-oxalato complexes, which are slowly destroyed by OH.bul. adsorbed on BDD. In anodic oxidn., oxalic acid is mineralized practically at the same rate as generated. [on SciFinder (R)]

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May 26, 2014