Irfan Ahmed Shaikh

Application of ozone in cotton bleaching with multiple reuse of a water bath

This paper discusses the effect of ozone bleaching on the quality of cotton fabric in terms of whiteness, dye pick-up, copper number and degree of polymerization (DP). The process parameters (pH, ozone dose and treatment time) were optimized, and the best whiteness (60–62) and quality of bleached fabric was obtained at pH 5, 45 min treatment time and room temperature. A strongly acidic environment and longer ozonation time decreased the quality of fabric by producing a higher copper number (0.18) and DP loss (51.5%). Statistical analysis of the experimental data using analysis of variance confirmed that process parameters significantly affected the bleaching efficiency. The process was then applied to bleach 20 different samples of cotton fabric re-using the same water bath, and the whiteness of ozone-bleached samples did not decrease, even after the 20th reuse of the water bath.

Dyeing and characterization of regenerated cellulose nanofibers with vat dyes

Recent advancement in dyeing of nanofibers has been accelerated to improve their aesthetic properties, however, achieving good color fastness remains a challenge. Therefore, we attempt to improve the color fastness properties nanofibers. Vat dyes are known for better color fastness and their application on nanofibers has not been investigated to date. Herein, we report dyeing of regenerated cellulose nanofibers (RCNF) that were produced from precursor of cellulose acetate (CA) followed by deacetylation process. The resultant RCNF was dyed with two different vat dyes and the color attributes were examined under spectrophotometer which showed outstanding color build-up. Morphological of CA before and after deacetylation and before and after vat dyeing was investigated under TEM, FE-SEM and SEM respectively. The vat dyed RCNF were further characterized by FTIR and WAXD. Excellent color fastness results demonstrate that vat dyed RCNF can potentially be considered for advanced apparel applications.

Environment Friendly Approach to Simultaneously Remove Unfixed Dyes from Textile Fabric and Wash-off Liquor

College of Earth & Environmental Sciences, University of the Punjab, Lahore, Pakistan, *E-mail: textilemaster@gmail.com Abstract A new idea was investigated in this study wherein the use of coagulants was assessed in the wash-off process to simultaneously remove unfixed reactive dyes from fabrics and washoff liquor. At the end of dark shade dyeing (5% owf) with C.I. Reactive Yellow 145, C.I. Reactive Red 194, and C.I. Reactive Black 5, fabrics were subjected to both conventional and new wash-off methods, and comparisons were made. The effectiveness of coagulant wash-off was evaluated in terms of the change in shade, wash fastness, rubbing properties, and colour difference values (ΔL*,ΔC*, Δh* & ΔE*). The colour removal efficiency (%) of liquor was considered as indicative of the removal of unfixed dyes from the fabric. Overall results have shown that the use of alum and MgCl2 coagulants during the wash-off process can achieve up to an 87% reduction in the colour of wash-off liquor, without compromising the colour properties of the dyed substrate.