Electrochemical incineration of dyes using a boron‐doped diamond anode
ABSTRACT 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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ABSTRACT: Biocatalyst behavior was comparatively evaluated under diverse microenvironments viz., self-induced electrogenic (bioelectrochemical treatment, BET) and anaerobic treatment (AnT) microenvironments, with real-field pharmaceutical wastewater. Relatively higher treatment efficiency was observed with BET (COD removal, 78.70%) over AnT (32%) along with the power output. Voltammetric profiles of AnT showed persistent reduction behavior, while BET depicted simultaneous redox behavior. BET operation documented significantly higher bio-electrocatalytic activity (kapp, 245.22 s(-1)) than AnT (kapp, 7.35 s(-1)). The electron accepting conditions due to the presence of electrode in the BET might contributed to higher electrogenesis leading to enhanced substrate degradation along with the removal of multiple pollutants accounting for the effective reduction of toxicity levels of wastewater. Even at higher organic loads, BET operation showed good treatment efficiency without process inhibition. Introduction of electrode-membrane assembly in anaerobic microenvironment showed significant change in the electrocatalytic behavior of biocatalyst resulting in enhanced treatment of complex wastewater.Bioresource Technology 12/2011; 102(23):10784-93. · 4.75 Impact Factor
- European Journal of Pain Supplements 01/2011; 5(1):94-95.
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ABSTRACT: This work presents a study on degradation of indigo carmine dye in a filter-press type FM01-LC reactor using Sb2O5-doped Ti/IrO2-SnO2 dimensionally stable anode (DSA) electrodes. Micro- and macroelectrolysis studies were carried out using solutions of 0.8 mM indigo carmine in 0.05 M NaCl, which resemble blue denim laundry industrial wastewater. Microelectrolysis results show the behaviour of DSA electrodes in comparison with the behaviour of boron-doped diamond (BDD) electrodes. In general, dye degradation reactions are carried out indirectly through active chlorine generated on DSA, whereas in the case of BDD electrodes more oxidizing species are formed, mainly OH radicals, on the electrode surface. The well-characterized geometry, flow pattern and mass transport of the FM01-LC reactor used in macroelectrolysis experiments allowed the evaluation of the effect of hydrodynamic conditions on the chlorine-mediated degradation rate. Four values of Reynolds number (Re) (93, 371, 464 and 557) at four current densities (50, 100, 150 and 200 A/m2) were tested. The results show that the degradation rate is independent of Re at low current density (50 A/m2) but becomes dependent on the Re at high current density (200 A/m2). This behaviour shows the central role of mass transport and the reactor parameters and design. The low energy consumption (2.02 and 9.04 kWh/m3 for complete discolouration and chemical oxygen demand elimination at 50 A/m2, respectively) and the low cost of DSA electrodes compared to BDD make DSA electrodes promising for practical application in treating industrial textile effluents. In the present study, chlorinated organic compounds were not detected.Environmental Technology 01/2012; 34(5-8):573-83. · 1.61 Impact Factor