Enviro-friendly biofinishing of cotton fibers using Aspergillus nidulans AJSU04 cellulases for enhanced uptake of Myrobalan dye from Terminalia chebula

• Aspergillus nidulans AJSU04 cellulase was substantiated for its efficacy to bleach cotton fibers.
• Prime focus was made on the kinetics and thermodynamics of Myrobalan uptake by the bio-bleached cotton fibers.
• Myrobalan sorption percentage onto bio-bleached cotton fiber was 93.33% with a dye sorption capacity of 0.0281 mg/g.

Dyeing and bleaching agents are increasingly used in the manufacture of fabric. Cellulase from Aspergillus nidulans AJSU04 was tested for its efficacy to bleach the fibers. The results were compared with a commercial bleaching agent sodium hypochlorite. Focus is made on dyeing the bio-bleached cotton fibers with Myrobalan dye [CAS:114921-10-7]. The kinetics and thermodynamics of Myrobalan uptake were evaluated. In comparison to sodium hypochlorite, cellulase was observed to enhance the fiber properties significantly. Response surface methodology (RSM) employing the central composite design (CCD) was used to optimize the bleaching conditions using cellulase. Factors including time, pH, temperature and fiber to bleach ratio are tested in CCD matrix. Maximum estimated test result (ETR) value of 281.67 Bekk sec and brightness percentage of 88.45% were obtained at optimal conditions 4 h, pH 5, 45 °C and 15 (w/v%) based on the mathematical model. Maximum Myrobalan sorption percentage onto cotton fibers was 93.33% with a dye sorption capacity of 0.0281 mg/g. Cotton fibers treated with A. nidulans AJSU04 cellulase was observed to enhance the Myrobalan dye uptake. They cotton fibers showed exceptional surface finishing after the dyeing process with maximum gloss. The results of the Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) of the cotton fibers showed structural changes through bleaching and dyeing in favor of Myrobalan treated with Cellulase. Henceforth, prior to dyeing, the cotton fibers can be bio-bleached in order to promote an excellent affinity towards the dye.

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