Recycling strategy for water contaminated with Reactive Black 5 in the presence of additives treated by simple ozonation

This study presents the treatment of wastewater contaminated with Reactive Black 5 (RB5) by simple ozonation in the presence of Na₂SO₄, Na₂CO₃ (inorganic additives), and their mixture. This oxidative treatment was a single step into a wastewater recycling process. At the end of each recycle, pH variation and UV/Vis spectroscopy of the ozonated samples were analyzed. The absorbency variations were correlated with the dynamics of ozone consumption after each recycle. The quality of the treated wastewater was evaluated by the dye fixation on cotton textile samples after each cycle. The quality of dyeing process was evaluated by a novel image processing method. The image analysis results demonstrated that the mixture of salts improved the fixation of dye after each of the eight recycling procedures. The presence of Na₂SO₄ favored the fixation of color and Na₂CO₃ catalyzed the reaction between dye and fiber. Moreover, the effect of Na₂CO₃ dominated the additives effect over the recycling ozonation of the RB5 dye.