Electrochemical incineration of dyes using a boron‐doped diamond anode

University of Castilla-La Mancha, Ciudad Real, Castille-La Mancha, Spain
Journal of Chemical Technology & Biotechnology (Impact Factor: 2.35). 06/2007; 82(6):575 - 581. DOI: 10.1002/jctb.1703


The electrochemical oxidation of a synthetic wastewater containing the model dyes alizarin red (an anthraquinone) and Eriochrome black T (an azoic compound) has been studied on a boron-doped diamond electrode (BDD) by both cyclic voltammetry and bulk electrolysis. The influence of the current density and dye concentration were investigated. The results obtained show that complete chemical oxygen demand (COD) and colour removal was obtained for both wastewaters. However, the nature of the pollutant, and specially the presence of functional groups (such as the azoic group) seems to strongly influence the performance and efficiency of the electrochemical process. The electro-oxidation of alizarin red behaves as a mass-transfer-controlled process. In such a system, an increase in the current density leads to a decrease in the current efficiency. This can be explained by direct or hydroxyl radical mediated oxidation. The contrary tendency has been observed in Eriochrome black T electro-oxidation. In this case, higher efficiencies were obtained working at high current densities. This may indicate that the mediated oxidation by electrogenerated reagent (such as peroxodisulphate) is the main oxidation mechanism involved in Eriochrome black T treatment. These compounds have a longer average lifetime than hydroxyl radicals, and it allows the reaction to be extended to the whole wastewater volume. This study has shown the suitability of the electrochemical process for completely removing the COD and total organic carbon and effectively decolourising of wastewaters containing synthetic dyes. Copyright © 2007 Society of Chemical Industry

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Available from: Marco Panizza, Oct 27, 2014
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    • "In the recent years, the electrochemical treatment of dyes has demanded a special attention, focused mainly on the comparison of different anode materials, for example: Pt, PbO 2 , Ti/Pt, Ti/Ru 0.3 Ti 0.7 O 2 , and BDD anodes [1] [2] [3] [4] or combination of different electrochemical technologies to remove dyes [1,5–11] (anodic oxidation with other processes such as oxidants production, ultraviolet light (UV) irradiation, ultrasound (US) irradiation, electro-Fenton (EF), photoelectro-Fenton (PEF) and so on). The electrochemical treatment by direct or indirect approaches [10], is based on the elimination of pollutants directly on the anode surface or/and, via production of @BULLETOH [9] [10] [11] [12] [13] [14] [15] [16] or additional oxidants [17] [18] [19] [20] [21] [22] [23] [24], such as chlorine, (per)bromate, persulfate, ozone, hydrogen peroxide, percarbonate, and others, directly on-site using only water, salt, and electrical energy. "
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    ABSTRACT: In this work, the role of chloro-species generated during the electrolysis of Rhodamine B (RhB) solutions containing chloride and perchlorate salts as supporting electrolytes was studied. Likewise, the effect of light irradiation in the activation of the oxidants is also evaluated. To do this, essays of electrolysis, photoelectrolysis, and chemical oxidation in the presence of light with the oxidant generated electrochemically were carried out. Results showed that RhB was effectively oxidized by electro-irradiated techniques. Color removal is faster than chemical oxygen demand (COD) and total organic carbon (TOC) removal, due to the rapid attack of chromophore group of the molecule. In general, light irradiation has a positive effect during the electrolysis of RhB at high current densities. In chloride media, light irradiation seems to favor the decomposition of hypochlorite produced. The effect of light irradiation is explained in terms of the activation of oxidants in the bulk of the electrolytic treatment by production of highly efficient radicals. Results of chemical oxidation essays may indicate that UV light irradiation has not a clear catalytic influence out of an electrolytic environment. The findings presented in this communication are described and discussed in the light of the existing literature.
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    • "However, a huge amount of sludge generated with the operation; received a greater concern of disposal or even further treatment of it. Similarly, it was reported that the oxidation of dyes with suitable chemical oxidant viz., chlorine, ozone, hydrogen peroxide, electrooxidation or wet-air oxidation are found to be inappropriate either due to the cost effectiveness or the by-products generated caused additional environmental concerns [3] [4] [5] [6] [7]. "
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    ABSTRACT: The aim of this investigation is to obtain thin films of nano-TiO2 on a borosilicate glass substrate using sol–gel template method. The thin film was immobilized with and without polyethylene glycol as filler media and annealed at 500 °C. Further, thin films were characterized by the IR, XRD, XRF and XPS analytical methods. The surface morphology of these films was obtained by the FE-SEM images and the BET specific surface area and pore sizes were obtained. The nano-TiO2 was, perhaps, formed a nanopillar onto the substrate. The thin films were successfully employed in the photocatalytic degradation of Alizarin Yellow (AY), an azo dye, from aqueous solutions using the UV-light irradiation under batch reactor operations. Various physico-chemical parametric studies, viz., effect of pH, Alizarin Yellow concentration and interfering ions were studied to deduce the mechanism involved in photocatalytic degradation of this pollutant. The time dependence degradation of Alizarin Yellow was provided to demonstrate the kinetics of degradation of this pollutant from aqueous solutions. It was observed that the degradation of Alizarin Yellow followed pseudo-first-order rate kinetics. Study was further extended with total organic carbon measurement using TOC analyser to demonstrate an apparent mineralization of Alizarin Yellow from aqueous solutions. The presence of several interfering ions or even OH scavengers suppressed the photo-catalytic action of thin films in AY degradation from aqueous solutions.
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    • "Among these anodes, BDD electrodes are preferred for AO because they interact very weakly with Å OH resulting in a much greater O 2 -overvoltage than other anodes and in an enhancement of organic removal with reactive BDD( Å OH) (Panizza and Cerisola, 2007, 2009). Thus, BDD is potent enough to mineralize aromatic pollutants from waters (Marselli et al., 2003; Carvalho et al., 2007; Sáez et al., 2007; "
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    ABSTRACT: The anodic oxidation of sulfanilic acid solutions has been studied in acidic medium using a divided cell with a boron-doped diamond (BDD) anode and a stainless steel cathode. Overall mineralization was achieved under all experimental conditions tested due to the efficient destruction of sulfanilic acid and all its by-products with hydroxyl radicals generated at the BDD anode from water oxidation. The alternative use of an undivided cell with the same electrodes gave rise to the coating of the cathode with polymeric compounds, thus preventing the complete electrochemical incineration of sulfanilic acid. The solutions treated in the anodic compartment of the divided cell were degraded at similar rate under pH regulation within the pH interval 2.0-6.0. The mineralization current efficiency was enhanced when the applied current decreased and the initial substrate concentration increased. The decay of sulfanilic acid was followed by reversed-phase HPLC, showing a pseudo first-order kinetics. Hydroquinone and p-benzoquinone were identified as aromatic intermediates by gas chromatography-mass spectrometry and/or reversed-phase HPLC. Maleic, acetic, formic, oxalic and oxamic acids were detected as generated carboxylic acids by ion-exclusion HPLC. Ionic chromatographic analysis of electrolyzed solutions revealed that the N content of sulfanilic acid was mainly released as NH(4)(+) ion and in much smaller proportion as NO(3)(-) ion.
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