Evaluation on dyeable, antibacterial and antioxidant properties of cotton fabric dyed with spent coffee grounds

Almost, spent coffee grounds are discarded to landfill, causing bad impacts on natural environment and generating a great waste because of removing beneficial bioactive compounds. This study investigated effects of dyeing techniques (exhaustion and pad-dry), types of mordants, sequences of adding mordants, temperature, exhausting time and concentration on dyeability of coffee extracts for cotton fabric in terms of color strength (K/S) and color difference (Delta E), thereby proposing a suitable treatment procedure. The experimental results showed that K/S and Delta E values were highest when mordanting with FeSO4.7H2O and CuSO4.5H2O. Simultaneously, highly antioxidant and antibacterial properties of treated cotton were quantitatively evaluated by UV-vis spectroscopy, scanning electronic microscopy, microbiologicalmethod and mechanical experiments. The content of polyphenols and tannins as well as the bacteriostatic activity of gram-positive and gram-negative species on treated cotton fabrics with coffee extracts were promising in future applications. Particularly, the total amounts of polyphenols and tannins, which could demonstrate antioxidant activity, were examined as 3.01 g/L (GAE) and 0.57 g/L (TAE), respectively. Especially, high reduction of E. coli bacteria and S. aureus bacteria on dyed specimens accounted for 78% and 80% as mordanting with CuSO4.5H2O, and it could be sustained to 75% and 48% after a washing cycle, respectively.