Effects of tannin mordanting on coloring and functionalities of wool fabrics dyed with spent coffee grounds

A large amount of functional materials remain in spent coffee grounds and form discards in the coffee beverage industry. Moreover, the extract from these spent coffee grounds contains sufficient amounts of pigments that can be utilized for textile dyeing. Therefore, in this study, the coloring and functional development of textiles by application of spent coffee extracts to wool fabrics was investigated. For preparation of the dyed wool fabrics, spent coffee grounds were dried after collecting them from a local coffee house. They were then subjected to extraction using a manual espresso machine. The spent coffee extract was applied to wool fabrics using an infrared (IR) dyeing machine, and after dyeing, the wool fabrics were post-mordanted in various concentrations of aqueous tannin solutions. The color and surface properties of wool fabrics dyed with spent coffee extract were investigated using spectrophotometry and Fourier-transform IR spectroscopy, respectively. And, their antibacterial and antioxidant capacities were also studied. The dyed wool fabrics were significantly brown in appearance, and their colorfastness to light improved upon mordanting with tannin. In addition, mordanting also improved the antibacterial and antioxidant capacity of the dyed wool fabrics.