Benign Felt-proofing of Wool Fibers Using a Keratinolytic Thermophilic Alkaline Protease

Non-deteriorative eco-friendly water-saving tactic for removal of vegetable matters from wool fleece using xylanase and cellulase

The carbonization of wool fleece (WF) is conducted to remove the adhered vegetable matter (VM) from contaminated WF using sulfuric acid, followed by drying and backing. This process has a deteriorative effect on WF and requires a tremendous quantity of water for rinsing WF after carbonization to remove any H2SO4 residuals. Herein, we propose an alternative eco-friendly water-saving process for the removal of VM from WF using enzymes. Cellulase-containing xylanase from the fungus Aspergillus terreus, and cellulase-free xylanase from the fungus Aspergillus flavus AW1 were used to remove the VM from WF. The effect of some process parameters on the amount of the removed VM was assessed. Alkali solubility as well as sulfur and cystine content were used to follow the alteration in the chemistry of the bio-treated WF. The fiber morphology was examined using scanning electron microscopy. The dyeability of the treated WF towards acid, reactive, and basic dyes was monitored. The results revealed that the removal of the VM from WF by applying the examined enzymes was effective and could be an appropriate, non-destructive, eco-friendly water-saving substitute to the conventional carbonization procedures. By virtue of enzyme specificity, the proposed process removed the VM without deteriorating the fiber.

Development of Environmentally Friendly Wool Shrink-Proof Finishing Technology Based on L-Cysteine/Protease Treatment Solution System

The particular scale structure and mechanical properties of wool fiber make its associated fabrics prone to felting, seriously affecting the service life of wool products. Although the existing Chlorine–Hercosett treatment has a remarkable effect, it can lead to environmental pollution. Therefore, it is of great significance to develop an environmentally friendly and effective shrink-proof finishing technology. For this study, L-cysteine was mixed with protease to form a treatment solution system for shrink-proof finishing of wool fibers. The reduction performance of L-cysteine and its effect on wool were compared with those of other reagents, demonstrating that L-cysteine has an obvious reduction and destruction effect on the wool scale layer. Based on this, L-cysteine and protease 16L were mixed in a certain proportion to prepare an L-cysteine/protease treatment solution system (L/PTSS). The shrink-proof finishing of a wool top was carried out by the continuous multiple-padding method, and the processing parameters were optimized using the response surface method. The results indicated that when the concentrations of L-cysteine and protease 16L were 9 g/L and 1 g/L, respectively, the wool was padded five times at 50 °C, and each immersion time was 30 s, the felt ball density of the treated wool reduced from 135.86 kg/m3 to 48.65 kg/m3. The structure and properties of the treated wool were also characterized using SEM, TG, and tensile strength tests, which indicated that the fiber scale structure was stripped evenly. Meanwhile, the treated fibers still retained adequate thermal and mechanical properties, indicating suitable application value. XPS, FT-IR, Raman, UV absorbance, and other test results revealed the reaction mechanism of L/PTSS with the wool fibers. After L-cysteine rapidly reduced the disulfide bonds in wool, protease can hydrolyze peptide chains more effectively, causing the scale layer to gradually peel off. Compared with the chlorination method and other protease shrink-proof technologies, L/PTSS can achieve the finishing effect on wool rapidly and effectively, without causing excessive pollution to the environment. The conclusions of this study provide a foundation for the development and industrial application of biological enzyme shrink-proof finishing technology.

One-pot multi-functional finishing of wool fabric using reactive nonionic softener

Crossbred wool is widely used in the textile and clothing fields. Nevertheless, the surface roughness of crossbred wool fabric is higher than that of Merino wool. Herein we propose a reactive nonionic softener (RNS) based on fatty acid (FA) and 2-amino-2-methyl propane diol (AMPD) to impart desirable multi-functions for crossbred wool fabric, such as improved smoothness, enhanced wettability, and induced resistance to felting shrinkage. Adopting the pad-dry-cure method, treatment of wool with the said softener was carried out using different concentrations of FA/AMPD condensate at different curing temperatures and durations. The results showed that the highest fabric surface smoothness was attained when wool fabric was treated with 3.5% (o.w.f.) RNS, and the curing temperature and time were 130 °C and 5 min, respectively. The surface smoothness of the treated fabric and its resistance to felting shrinkage were increased by 21.7% and 90% respectively. The effects of treatment of wool with the RNS on its bending stiffness, air and water permeability, yellowness, electrostatic charge, and ultraviolet protection factor (UPF) were monitored. The reaction mechanism between the used RNS and wool was studied using FTIR spectroscopy. Scanning electron microscopic investigation showed a layer of the used RNS on the surface of the treated fabric. The finished fabric retained its air permeability and dyeability with anionic dye. The imparted fabric smoothness was find to be durable against washing until 5 washing cycles, and decreased by 5.5% of after 10 washing cycles respectively.

Green method for improving performance attributes of wool fibres using immobilized proteolytic thermozyme

Wool has the tendency to turn into felt during agitation in washing machines. Thus, a benign non-polluting method for the production of machine-washable wool was developed herein. Initially, a proteolytic bacteria was isolated from hot region soil. The bacterial isolate was identified as Bacillus safensis FO-36bMZ836779 according to the 16S rRNA gene sequencing. Afterwards, the extracellular protease produced by this isolate was covalently immobilized in order to enhance its stability under non-ambient conditions which are usually adopted in industrial sectors like textile industries. Sericin, which is usually discharged into degumming effluent of natural silk, was utilized to prepare the immobilization carrier. Box–Behnken design was adopted in order to hone the preparation of the sericin–polyethylene–imine–glutaraldehyde activated agar carrier. The pH and temperature profiles of the free and immobilized proteases were compared. Later, wool fibres were bio-treated with both the free and the immobilized enzymes. The effect of process conditions on the resistance of the bio-finished wool to felting was investigated. The alteration in the fibre morphology was monitored using SEM. Amino acid analysis and alkali solubility tests were adopted to assign any change in the chemical structure of the bio-treated wool. The influence of bio-treatment of wool on its inherent properties was assigned. Results revealed that bio-treatment of wool with the said enzyme led to production of machine-washable wool without severe deterioration in the fibres’ properties. In an energy- and water-consuming process, the hot solution from bio-treatment bath was used successfully in dyeing of wool.

Bioscouring of wool fibres using immobilized thermophilic lipase

The hydrophobic nature of wool induced by its surface lipid barrier hinders its wettability during processing. Scouring of wool is conducted to remove this lipid barrier and facilitate any wet processes. Scouring of wool is conducted using soda ash followed by rinsing with huge amount of water to ensure complete removal of alkali. This work aimed at utilization of thermophilic lipase enzyme for removal of wool surface lipid barrier without deterioration on the fibre interior. A thermally stable lipase enzyme was produced from thermophilic microorganism; namely Bacillus aryabhattai B8W22, and was utilized in bio-scouring of wool. The produced enzyme was immobilized on sericin-based discs to enhance its stability and to make it reusable. The activity of both free and immobilized lipase enzymes at different conditions was assessed. The effects of bio-scouring of wool on its dyeability with acid, basic, and reactive dyes, as well as on some of its inherent properties, were monitored. Results showed that the bio-scoured wool exhibits enhanced dyeability with the said classes of dyes more than that of conventionally scoured samples. One-bath scouring and dyeing of wool fibres in two successive steps was conducted to reduce consumption of water and energy during wet processing of wool.