Cotton fabric modification through ceric (IV) ion-initiated graft copolymerisation of 2-methacryloyloxyethyltrimethyl ammonium chloride to enhance the fixation of reactive dyes

An environmentally friendly dyeing method with highly enhanced dye fixation was proposed to reduce wastewater release in the dyeing of reactive dyes. Cotton fabrics were modified and prepared using the ceric (IV) ion-initiated graft copolymerisation of 2-methacryloyloxyethyltrimethyl ammonium chloride (DMC). These modified cotton fabrics were first applied to reactive dyeing without the addition of inorganic salt. Grafting was confirmed by obtaining Fourier transform infrared spectra. Reaction conditions, including the initiator concentration, DMC-to-cotton mass ratio, reaction time and acid concentration, were optimised to enhance the grafting amount of DMC and obtain high dye exhaustion. The surface morphological characteristics and strength properties of the modified cotton were evaluated. When the amount of the grafted DMC on cotton was 0.114 mmol/g, the fixation of C.I. Reactive Blue 19, C.I. Reactive Red 195 and C.I. Reactive Yellow 145 could reach 85.6, 96.5 and 98.5 %, respectively; these respective values were 24.0, 24.4 and 23.2 % higher than those obtained using the conventional dyeing method in the presence of inorganic salt. Wastewater indexes, including chemical oxygen demand (CODCr), colourity (extent or degree of colouring) and ammonia–nitrogen content, were determined. The recyclability of the DMC solution was also examined to show the applicability of the proposed dyeing method.