Electrochemical Decolorization Of Indigo Carmine On ACF Electrodes

As the indigo has the unusual dark blue, it takes the indigo dyestuffs representative, which is paid attention to for a long time. The output synthesize of the indigo is approximately 22000 tons every year, accounting for 3% of every year world dye ultimate output. Because our country's indigo production accounts for the world ultimate output above 60%, China is the great nation of the world indigo producing. The indigo dye waste water is used traditional methods to achieve the ideal processing effect with so many difficulties that industry is always puzzled by the indigo waste water treatment.Most of studies on dye wastewater treatment with electrochemical method focus on new electrodecolorization technology and electrode. Activated carbon fiber (ACF) is a kind of porous, three dimensional electrode with prospective application in dye wastewater treatment.The electrochemical decolorization of indigo carmine was carried out in a two-compartment cell separated (or not) by cation exchange membrane using activated carbon fiber (ACF) as the working electrode (anode or cathode) and the counter electrode under potentiostatic or galvanostatic model. The effects of electrode potential and current density on the decolorization kinetics, color, total organic carbon (TOC) and chemical oxygen demand (COD_cr) removal ratio were all investigated. The onset reduction potential, the onset oxidation potential for indigo carmine on ACF and the current density when the paired electrolysis acted were confirmed. Meantime, the energy consumption and removal equivalent were calculated.The results obtained are shown that the decolorization of dye on ACF electrodes by paired electrolysis is feasible.As for the results of the potentiostatic model separated by membrane: (1) in the different range of electrode potentials, the decolorization results from adsorption, electrooxidation, electroreduction; the onset reduction potential and the onset oxidation potential for indigo carmine on ACF are -0.3V and 0.4V, respectively; (2) the pseudo-first order kinetics equations are both obtained in the range of electrooxidation and -0.3V ～ -1.7V electroreduction; (3) the color removal ratio may be up to 98.1% and 86.6%, respectively for the electroreduction and the electrooxidation.As for the results of the galvanostatic model separated by membrane: (1) in the different range of current densities, the decolorization results from adsorption, electrooxidation, electroreduction; (2) the pseudo-first order kinetics equations are both obtained in the range of...