Chlorella Zofingiensis Astaxanthin Production in Photobioreactors for Natural Wool Dyeing: Effects of Chitosan, Air Plasma, and Argon Plasma Surface Treatments on Dyeing Performance

Abstract A significant amount of dyes in the textile industry include synthetic compounds, which have generated environmental concerns due to their detrimental effects on nature. This study investigates the production of Chlorella zofingiensis -derived astaxanthin in Roux-type Panel Photobioreactor (PBR) and Bubble Column PBR, driven by the demand for more environmentally friendly dyeing methods, and assesses its efficacy as a bio-based colorant for wool fabrics. Bubble Column PBR provided higher biomass (1.83 ± 0.02 g L −1 ) and astaxanthin concentrations (15.83 ± 1.96 mg L −1 ). The ethanolic astaxanthin extract demonstrated free radical scavenging activity of 88.60 ± 0.91% and no cytotoxic effects on L929 cells. Then, the effects of pretreatments of wool fabrics with atmospheric air plasma, argon plasma, chitosan, and alum were proposed. The wool fabric treated with chitosan had highest colorant adsorption as 70.20 ± 0.26% and color strength as 1.93, while alum-mordanted fabric was 30.00 ± 0.01% and 1.31, respectively. The color fastness to washing and perspiration of the chitosan-treated samples were measured as 4–5 (good to excellent); therefore, chitosan treatments can be considered as a more preferable candidate compared to the alum-mordanted fabric. The results show that astaxanthin pigment has the potential to dye wool fabric using various surface treatments. Up till now, according to the knowledge of the authors, this is the first report demonstrating astaxanthin derived from C. zofingiensis for emphasizing its suitability as a natural pigment in the textile applications.