Journal of Applied Electrochemistry, Vol.39, No.12, 2569-2577, 2009
Redox mediated electrochemical method for vat dyeing in ferric-oxalate-gluconate system: process optimization studies
Preliminary efforts were made to identify alternative ligands for relatively greener and cheaper than triethanolamine (TEA), leading to a new ferric-oxalate-gluconate mixed ligand system as a potential alternative. Cyclic voltammetry was employed to study the mechanism involved. A low concentration of electrogenerated Fe-II-oxalate is transformed into Fe-II-gluconate, which is the reducing agent in the overall process. The influences of electrolyte medium, electrode material, nature of dye, dye concentration, material to liquor ratio (MLR), and other related parameters were studied to arrive at optimum experimental condition. Copper cathode and stainless steel anode were the material of choice. The optimum cathode current density was found to be 2.30 mA cm(-2). Under optimum condition, both cotton fabric and yarn could be efficiently dyed using this electrochemical process. The electrolyte could also be recycled. Color intensity for different dyed materials was evaluated using K/S values according to the Kubelka-Munk equation.
Keywords:Indirect electrolysis;Ferric-complex;Calcium gluconate;Oxalic acid;Vat dyes;Cyclic voltammetry;Electrochemical dyeing