Ozone Assisted Electrocoagulation for Decolorization of C.I. Reactive Black 5 in Aqueous Solution: An Investigation of the Effect of Operational Parameters

College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, People's Republic of China
Separation and Purification Technology (Impact Factor: 3.09). 06/2007; 55(2):238-245. DOI: 10.1016/j.seppur.2006.12.013


This study was performed to investigate the variables that influence the efficiency of color removal from a solution containing an azo dye (C.I. Reactive Black 5, abbreviated here as RB5) by the combination of ozonation and electrocoagulation at iron electrodes. Several working parameters, such as initial pH, initial dye concentration, current density, salt (K2SO4) concentration, temperature, ozone flow rate and distance between the electrodes, were studied in an attempt to achieve higher color removal efficiency. The experimental results reveal that the color of RB5 in the aqueous phase was removed effectively. Under the conditions of an initial dye concentration of 100 mg/L, initial pH of 5.5, current density of 10 mA/cm2, salt concentration of 5000 mg/L, temperature of 20 °C, ozone flow rate of 20 mL/min (ozone dose 0.20 g/h), and interelectrode distance of 1 cm, the color-removal efficiency reached 94%, corresponding to a reduction in COD of more than 60%. The energy consumption of the technique was approximately 33 kWh/kg of COD removal.

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    • "Therefore, the EC method can be considered an effective nitrate removal method [17]. Some previous studies have obtained over 90% color removal during the decolorization of effluents in textile wastewater [18] [19] [20] [21] [22] [23]. "
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    CLEAN - Soil Air Water 05/2014; 42(5). DOI:10.1002/clen.201300086 · 1.95 Impact Factor
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    • "Thus same amount flocs would be produced in the solution. The adsorption capacity of flocs is limited and specific amount of flocs is able to adsorb specific amount of dye molecules [22]. So, with increasing of dye concentration, amount of produced flocs is insufficient to adsorb all dye molecules, therefore dye and COD removal decreases. "
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    ABSTRACT: In this research, the efficiency of electrocoagulation treatment process using aluminum electrodes to treat synthetic wastewater containing Reactive Red198 (RR198) was studied. The effects of parameters such as voltage, time of reaction, electrode connection mode, initial dye concentration, electrolyte concentration, and inter electrode distance on dye removal efficiency were investigated. In addition, electrical energy consumption, electrode consumption, and operating cost at optimum condition have been investigated. The results showed that dye and chemical oxygen demand removals were 98.6 and 84%, respectively. Electrode consumption, energy consumption and operating cost were 0.052 kg/m3, 1.303 kWh/m3 and 0.256 US$/m3, respectively. Dye removal kinetic followed first order kinetics. It can be concluded that electrocoagulation process by aluminum electrode is very efficient and clean process for reactive dye removal from colored wastewater.
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    • "The decomposition of the chromospheres in dyes can be achieved by injecting a strong oxidizing agent such as ozone. However, a large dose of ozone, which is not economically feasible, is usually required for decolorization due to the significant amount of auxiliary chemicals [5]. The adsorption process is one of the effective methods used to remove dyes from aqueous solution. "
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    ABSTRACT: The removal of color from synthetic wastewater containing Reactive Black 5 was experimentally investigated using direct current electrocoagulation at iron electrodes. The effects of operational parameters such as current density, initial pH, electrolysis time, initial dye concentration and solution conductivity on color removal efficiency were investigated in this study. The optimum operating range for each of these operating variables was experimentally determined. The experimental results show that the color of Reactive Black 5 in the aqueous phase was removed effectively. Under the conditions of an initial dye concentration of 100 mg L(-1), initial pH of 5, current density of 4.575 mAcm(-2), salt concentration of 3000 mg L(-1), temperature of 20 degrees C, and interelectrode distance of 2.5 cm, the color removal efficiency reached 98.8%. Electrical energy consumption in the above conditions for the decolorization of the dye solution containing Reactive Black 5 was 4.96 kWh/kg dye. Results show that the first-order rate equation provides the best correlation for the decolorization rate of Reactive Black 5.
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