One-step process for bio-scouring and peracetic acid bleaching of cotton fabric

In this study, we investigated the utilization of peracetic acid (PAA) formed in situ from reaction of tetraacetylethylenediamine (TAED) with sodium perborate to affecting simultaneous desizing and bleaching whereas cellulase, pectinase and their mixture were utilized to affect bio-scouring. In this regards, two parallel studies were designed, the first were, separate desizing either with PAA or ammonium persulphate followed by bio-scouring and PAA bleaching in one step. The second sets of experiments were involved one-step process for desizing, bio-scouring and PAA bleaching. Residual starch, fabric wettability, residual wax content retained tensile strength elongation at break and fabric whiteness index were taken as a measure of the extent of cotton desizing, scouring and bleaching. Results obtained show that, cotton fabric bleached with PAA and either cellulase or pectinase enzyme shows excellent wettability and acceptable whiteness index (WI). This indicated that the combination between PAA and either cellulase or pectinase enzyme did not detract from the effectiveness these enzyme towards bio-scouring or the effectiveness of PAA towards low temperature bleaching of cotton fabric. The optimum bleaching recipe consists of utilizing a bath containing 25 g/L, TAED; 15 g/L, sodium perborate; 2 g/L, pectinase and 5 g/L Egyptol® (non-ionic wetting agent) and the treatment was carried out at 60 °C for 90 min. Desizing with PAA prior to bio-scouring and bleaching enhances the WI to 73.5 the retained tensile strength remain at 85.5%. One-step process for desizing, bio-scouring and PAA was also feasible, which involved treatment the loomstate cotton fabric with the same recipe. Although, the fabric bleached with one-step process shows lower WI compared with two-step processes, but its wettability was excellent and no detectable residual starch was found.