Optimized preparation and dyeing of Pterocarpus santalinus waste extract for enhancing healthy and environmental care performance of wool fabric

P. santalinus waste powders were utilized to prepare the aqueous extracts for the dyeing of wool fabric. The extraction and dyeing processes of P. santalinus were optimized for obtaining the dyed fabric with high color strength and flavonoids content. The antibacterial, antioxidant and aqueous Cr(VI) removal capacity of the dyed fabric was then examined and compared with other two plant (P. tinctorius and Lycium ruthenicum Murray) material extract dyed wool fabrics. The results indicated that the addition of ethanol in aqueous solvent could increase the content of colorants and flavonoid compounds in P. santalinus extract when soxhlet apparatus was used. The highest extraction effectiveness of P. santalinus was achieved at ethanol concentration of 80%. High dyeing temperature or low pH level caused an almost linear increment in color strength and flavonoid content of the dyed fabric. Optimum dyeing of wool fabric could be conducted when 35 mL of P. santalinus extract was used to prepare 100 mL of dyeing bath. The dyed fabric not only showed unique color, but also presented better antibacterial, antioxidant and Cr(VI) removal capacity, which were higher than those of the other two dyed fabrics. Increasing color strength or flavonoid content could enhance their functionalities.