Turmeric dyeing and chitosan/titanium dioxide nanoparticle colloid finishing of cotton fabric

Abstract

The possibility of combining the finishing and natural dyeing of cotton fabric has been studied using a single-stage, pad-dry-cure technique, by treating it with chitosan/titanium dioxide nanoparticle colloids and turmeric dye. Different parameters have been studied to optimise the process, such as the chitosan/TiO₂ nanoparticle colloid concentration, citric acid crosslinker concentration, sodium pyrophosphate catalyst concentration, dye concentration, <em>p</em>H, curing time, and temperature. To investigate the effects of combined treatment on the dyeing and functional properties of the treated cotton fabric, its ultraviolet protection factor, antibacterial activity, self-cleaning properties, rigidity, colour strength (<em>K</em>/<em>S</em>), fastness behaviour, nitrogen content, and wettability are determined. In addition, the cotton fabric surface is characterised using scanning electron microscopy. The samples treated with chitosan/TiO₂ in the presence of citric acid exhibit excellent protection against ultraviolet radiation as well as antibacterial activity. The optimum conditions are 0.75% TiO₂(w/v), 10% dye (w/v), 2.5% chitosan (w/v), 30 g/L citric acid, 4 g/L sodium pyrophosphate, 70°C drying temp. and 5 min drying time, 180°C curing temp. and 2 min curing time. The results also indicate the efficiency of the treatment in improving the self-cleaning properties of the fabric. A significant improvement in the colour fastness is observed for the treated fabrics.