Eco-friendly sulfur dyeing of cellulosic woven fabrics

Abstract

This work demonstrated that conventional sulfur dyeing, which poses environmental problems, can be modified by using safer chemicals. The results indicate that: i) using reducing sugars as eco-friendly reductants results in an improvement in the extent of coloration; ii) the extent of improvement is determined by the reductant type; i. e., liquid glucose (LG) > thiourea dioxide (TUD) > glucose (G) > molass (M), dye/reductant ratio, as well as type of woven cellulosic fabric; i. e., viscose > cotton > linen; iii) raising the dyeing temperature to 80 degrees C for 45 min, increasing NaCl concentration to 30 g/L, and/ or minimizing the material-to-liquor ratio to 1/10 brings about an improvement in the extent of coloration; iv) efficiency of dye fixation is determined by the nature of the oxidant and follows the descending order (NH4)(2) S2O8 > Na-perborate > H2O2 > none; and v) post-softening has positive impacts on the softness degree and washing fastness, as well as rubbing fastness properties, especially in the case of using the cationic softener, regardless of the sulfur dye used