Comparison of direct and reactive dyeing in terms of technical, economic and ecological perspectives

Abstract

Today, the concept of sustainable and environmentally friendly production has gained great importance. Currently, reactive dyes are predominantly used in the dyeing of cotton fabrics. However, when direct dyes are used in light and medium shades, they have the potential to provide significant advantages in terms of wastewater load since they require little to no alkali and have very low salt requirements. In this study, 100% cotton single jersey fabric samples were dyed with yellow, red and blue direct dyes belonging to trichromatic combination at 4 different depths, 0.5-1-2-3%, and the obtained colour yield values were statistically analysed. Then, fastness tests were conducted on the fabric samples. In the second stage of the study, the colours of the fabric samples dyed with direct dyes at 1% depth were taken as reference and these colours were matched with reactive dyes. Then, the same colour obtained by direct dyeing and reactive dyeing was compared with each other in terms of technical (colour, washing, rubbing, water, perspiration and light fastness values), economic (chemical, energy and water consumption for 1 kg fabric dyeing (including after-treatments)) and ecological (chemical oxygen demand, biological oxygen demand and pH value of the dyeing wastewater) aspects.