Curcumin Nanoparticles as a Pigment of Polyamide Textiles: Influence of Conditions in the Exhaust Dyeing and Evaluation of Wastewater Toxicity

Abstract

The growing demand for eco-friendly and sustainable solutions in textile dyeing has attracted interest in natural dyes, since the synthetic counterparts may be potentially damaging to the environment and require the use of additives to efficiently bind them to the fibers. Curcumin, a natural dye derived from Curcuma longa L. rhizomes, has attracted attention due to its notable biological activity and vibrant yellow-orange hue; however, its direct application remains limited by challenges related to dye fixation and color fastness. This study aimed to evaluate the use of curcumin nanoparticles in the dyeing of polyamide 6.6, as well as to assess the toxicity level of the effluent generated during the exhaust dyeing process. Colloidally stable nanoparticles with average sizes of 454 and 419 nm were obtained with PVP (polyvinylpyrrolidone) and Poloxamer 407 as the polymeric stabilizer, respectively. A factorial 24-1experimental design was implemented, showing a reduction in color intensity at higher dyeing temperatures, while acidic conditions enhanced dye uptake, leading to improved color depth. Two formulations were selected for a more detailed characterization. Regarding the wash currently used by the textile field, the scores found demonstrated that color did not change during washing. Excellent ratings were found in the rubbing and perspiration fastness and the ultraviolet protection factor for the textiles dyed with PVP and Poloxamer 407 stabilizers. The wastewater of the dyeing process under selected experimental conditions was evaluated with respect to the phytotoxicity, genotoxicity, and cytotoxicity in in vivo models. Based on the results, the wastewater samples analyzed may be environmentally safe.