Water is used in the textile industry, mainly, as vehicle for chemicals and dyes used in the dyeing and finishing processes of textile fibers. In this work we studied the reuse of wastewater generated in the dyeing of nylon 6.6 (PA6.6) fabrics and treated by adsorption process with nylon 6.6/chitosan (80/20) blend flakes was studied. To produce the wastewater PA 6.6 fabrics were dyed with the acid dyes Yellow Erionyl RXL, Red Erionyl A-3B and Navy Blue Erionyl R. The efficiency in color removal of the adsorption process varied between 97-98%, with exception of the effluents from Yellow Erionyl RXL dyeing, where only efficiencies of 65% (wastewater with auxiliaries) and 72% (without auxiliaries) were obtained. The reuse of the treated wastewater was studied in dyeing of knitted nylon 6.6 fabrics with the same dyes. ΔE values (color difference relative to a standard dyeing with distilled water) of the dyeings with light and medium colors varied from 0.24 to 1.05 for the wastewater of monochrome dyeing, and from 0.71 to 1.07 for the wastewater of trichrome dyeing and are compatible with industrial standards (ΔE < 1.1). It could be concluded that the reuse of treated wastewater from polyamide dyeing under the tested conditions is feasible, although with some restrictions for yellow especially.
Polyamide 6.6; acid dyes; wastewater treatment, recycling
