Comparación de técnicas avanzadas para el tratamiento de una solución modelo de índigo: Electro incineración, coagulación química y enzimático

Indigo blue is one of the most important textile dyes. The wastewaters for indigo blue used are thought to be contaminated because; indigo can be oxidized to isatin, which is hydrolyzed to antranilic acid, a compound that is toxic to aquatic life. Indigo oxidation was evaluated using a model solution that simulated a textile wastewater. Three oxidation systems: electro incineration, chemical coagulation using Al2 (SO₄)₃, and enzymatic degradation with laccase. With electro incineration, the indigo solution was completely discolored; chemical oxidation demand diminution was 98% in approximately 3 hours and indigo blue was mineralized with no sludge production. Chemical coagulation with 40 mg L^-1 sulfate aluminum removed some color though control of pH was necessary. At pH 5, the chemical oxygen demand was reduced by 76%, with sludge formation. Laccase enzyme, processing required 72 hours for complete discoloration of the indigo model solution; chemical oxidation demand diminution was nearby 50%, but laccase could not mineralize the dye. Toxicity assays indicated that the processes generated more toxic products than the control.