Electro-Fenton degradation of synthetic dye mixture: influence of intermediates. J Environ Eng Manage

J. Environ. Eng. Manage 01/2009; 19:277-282.


Electro-Fenton process is a potentially useful oxidation process for destroying toxic organic compounds in aqueous medium. In this study, the electro-Fenton degradation of a solution mixture of Malachite Green (MG) and Orange II catalyzed by ferric ions was examined. Results showed that this system could degrade and mineralize the dye mixture. It was shown that absorbance decrease in MG was accelerated in the presence of Orange II, whereas absorbance decrease of Orange II at the same conditions was depressed. This behavior was attributed to generation of hydroquinone-like intermediates from degradation of Orange II that can accelerate Fenton reaction by reduction of Fe 3+ to Fe 2+ ions. GC-MS detection of the products formed in the Orange II electro-Fenton degradation showed the generation of dihydroxynaphthalene compounds that are probably responsible for acceleration of MG degradation.

Download full-text


Available from: Vahid Vatanpour
  • Source
    • "dye wastewater include adsorption [6] chlorination and ozonation [7] [8], electrochemical methods [9] [10], biological methods [11] [12], and chemical oxidation [12] [13]. However, because of high dye concentrations and the increased stability of synthetic dyes, these methods are becoming less effective for the treatment of colored industry effluents. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Sono-electrochemical degradation of Orange G (OG) in acidic aqueous solutions using 22.5 kHz ultrasonic irradiation with platinum grid anode and carbon felt cathode was investigated. Effects of various operating parameters such as ultrasonic power, initial pH, initial dye concentration, electric current, and Fe(II) concentration on the degradation of OG were examined. Additionally, sono-electrochemical degradation of substrate was evaluated in natural mineral water and seawater. The obtained results show that the degradation increased with increasing ultrasonic power up to 15 W. Significant degradation was achieved at pH 3 with an applied current of 100 mA and a Fe(II) concentration of 0.05 mM. It was found that sonoelectrofenton process is an efficient technique for the degradation of OG even in complex matrices such as natural mineral water and seawater. Its high performance arises from the coupling between ultrasound irradiation and the in situ electrogeneration of Fenton’s reagent. A significant synergy index of 4.5 was observed for the sono-electrochemical treatment of water contaminated by OG.
    Full-text · Article · Dec 2015 · Desalination and water treatment
  • Source
    • "Rao et al.[48]reported a small effect of cathodes like Al, Cu, Pt and Zn on the decolorization and COD removal of Malachite Green by AO with a Pt anode, indicating its poor electroreduction ability. Better results were obtained by EF with Pt/graphite-felt tank reactors[18,19]. Oturan et al.[19]found total decolorization in 22 min and 95% COD abatement in 420 min when 250 cm 3 of 0.5 mmol dm À3 Malachite Green in 0.05 mol dm À3 Na 2 SO 4 with 0.2 mM Fe 3+ were electrolyzed at pH 3.0 and 200 mA. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The degradation of 100 cm3 of 177 mg dm-3 of the triphenylmethane dye Malachite Green oxalate at pH 3.0 was studied by anodic oxidation with stainless steel cathode (AO-SS), AO with air-diffusion cathode (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF) with UVA light. The main oxidizing species were hydroxyl radicals formed from either water oxidation at the anode surface or in the bulk between added Fe2+ and H2O2 generated at the air-diffusion cathode. The use of a Pt anode led to slower decolorization and mineralization than BDD in all treatments because of the higher oxidation power of the latter. The decolorization was much faster for EF and PEF compared to AO-SS and AO-H2O2 due to the contribution of hydroxyl radicals in the bulk. PEF allowed the quickest color removal by the rapid Fe2+ regeneration from the photolysis of Fe(III) complexes with oxalate. The most powerful process was PEF with BDD, which yielded total decolorization in 6 min and 97% mineralization at 240 min operating at 100 mA cm-2, thanks to hydroxyl radicals formed at the anode surface and in the bulk along with the photolytic action of UVA radiation. The evolution of final carboxylic acids like maleic, fumaric, succinic, acetic, oxalic, formic and oxamic was followed by ion-exclusion HPLC. All these acids and their Fe(III) complexes were removed more slowly with Pt anode. The initial N atoms of the dye were pre-eminently accumulated as NH4+ ion, along with small amounts of NO3- ion.
    Full-text · Article · Nov 2015 · Electrochimica Acta
  • [Show abstract] [Hide abstract]
    ABSTRACT: The peroxi-coagulation process has been used for treatment of aqueous solutions of four dyes with different structures, namely C.I. Basic blue 3 (BB3), Malachite green (MG), C.I. Basic red 46 (BR46) and C.I. Basic Yellow 2 (BY2) at pH 3.0. The experiments were conducted using an open, undivided and cylindrical glass cell in the presence of sulfate electrolyte media with a carbon nanotube–polytetrafluoroethylene (CNT–PTFE) electrode as cathode. Outer and inside diameters of used carbon nanotube were 8–15nm and 3–5nm, respectively. Up to 90% decolorization of each of the dyes occurred in less than 10min. BY2 has been used as a model among the dyes to study the effect of operational parameters, modeling of process by artificial neural networks (ANN) and calculating operation costs. TOC measurements of the BY2 and mixed dyes showed 92% and 93% decontamination at 6h, respectively. Relationship between the predicted results of the designed ANN model and the experimental data was also conducted. The ANN model yielded a determination coefficient of R2=0.989 and could describe the decolorization efficiency under different conditions. Our results also showed that the peroxi-coagulation process with CNT–PTFE electrode as cathode could removal 95% and 90% of BY2 and mixed dyes in 40min from a real wastewater. The operation cost for decolorization of the dye solution containing BY2 was calculated (≈21.7 US$ (kgdye removed)−1).
    No preview · Article · Feb 2010 · Journal of electroanalytical chemistry
Show more