Selection of an electrolyte to enhance the electrochemical decolourisation of indigo. Optimisation and scale-up.
The investigation presented here focussed on the electrochemical decolourisation of a commercial, textile indigo dye, in an undivided electrochemical cell using graphite electrodes. The decolourisation values obtained employing halide salts--sodium chloride, potassium bromide and potassium iodide--and a reductive agent--sodium meta-bisulphite--as electrolytes are higher than those attained when no electrolyte was used. The highest decolourisation value at a low level of electric power consumption was obtained with sodium chloride. Besides, this electrolyte is usually found in the coloured wastewaters of textile industry. Thus, a detailed study was carried out to determine the influence of electrolyte--sodium chloride--and dye concentration on the efficiency of the process expressed in terms of energy consumption and extension of the decolourisation reaction. The scale-up of the treatment with sodium chloride was satisfactorily tested in a 20 l cell.
Cameselle
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Department of Chemical Engineering, University of Vigo, 36310 Vigo, Spain. claudio@uvigo.es
Pazos
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Sanromán
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MA
D003116:Color; D004396:Coloring Agents / Q000737:chemistry*; D004560:Electricity; D004563:Electrochemistry; D004573:Electrolytes / Q000737:chemistry*; D007203:Indigo Carmine; D007211:Indoles / Q000737:chemistry*; D010084:Oxidation-Reduction; D012965:Sodium Chloride / Q000737:chemistry*; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods
D004396:Coloring Agents; D004573:Electrolytes; D007211:Indoles; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D007203:Indigo Carmine