Reduction of water and salt in the dyeing acrylic yarn

Abstract

The textile industry is considered a major generator of environmental impacts through its effluent discharge. Options aimed at environmental preservation have been studied with the aim of reducing chemical inputs and water resources. This study presents the possibility of replacing part of the water with soybean oil in acrylic yarn dyeing processes, where a cationic dye trichomy was used, composed of Basic Yellow 28, Basic Red 46 and Basic Blue 3, in order to reduce the amount of salt in this phase of the process. First, mixtures of water and soybean oil were evaluated, where it was observed that the dyed yarns that obtained more intense shades were with the mixture of 75% oil and 25% water, without the addition of salt. These yarns were sent to fastness to rubbing, as well as fastness to washing tests. These tests showed that the original characteristics were maintained when dyed with soybean oil and without sodium chloride, and the fastness score for both tests was maximum, the same results obtained in the yarns dyed by the conventional method. When the stains were analyzed, it was possible to determine that these yarns were equalized. It was also possible to conclude that the pseudo-1st order model adjusted to the conventional dyeing with sodium chloride. The good results of dyeing in an oily medium can be explained by the hypothesis that the oil acts as a vehicle that carries the dyes to the surface of the fiber, since the dyeing occurs with the dye solubilized in the aqueous phase. Thus, it is concluded that the dyeing of acrylic yarns is possible with the application of soybean oil with water, generating a reduction in the use of salt and water in the process, and reuse of the oil after dyeing.