Bleaching of Blended Fabrics Containing Calcium Alginate Fibers Based on Alum/NaOH/H2O2

Abstract

Calcium alginate fiber represents a novel class of green and environmentally friendly biomass fibers with exceptional properties. It holds significant application potential in both the medical and healthcare sectors, as well as in the high-end textile fabric industry. However, its broader application in the textile and apparel fields is constrained by its limited resistance to salt and alkali, and its propensity to gel in bleaching environments. The bleaching pretreatment of calcium alginate fiber remains a challenging endeavor. In this study, we introduce a bleaching process that employs alum and sodium hydroxide as fiber protectants to enhance the alkali resistance and bleaching performance of calcium alginate fibers in an oxygen-rich bleaching environment. By utilizing alum as a fiber protector, sodium hydroxide (NaOH) as an alkaline agent, and a 30% hydrogen peroxide solution (H₂O₂) as a bleaching agent, the calcium alginate fiber fabric undergoes bleaching and treatment. The interaction between alum and sodium hydroxide generates tetrahydroxy structures, which increase the cross-linking degree of the calcium alginate macromolecular chains. Simultaneously, Al³⁺ ions partially replace Ca²⁺ ions in the "egg box" structure of the alginate fibers, thereby improving the fibers' resistance to alkali and bleaching. This research presents an innovative bleaching process for calcium alginate fibers, offering a solution to the challenge of poor bleaching resistance and expanding the potential applications of these fibers.