| In a low carbon economy time that many countries advocate clean environmental protection, energy conservation and emissions reduction, the dyeing green processing is imperative. The application of bio-scouring is a good example. Bio-scouring is an ideal alternative method to remove the non-cellulosic impurities from raw cotton by specific enzymes to make the surface more hydrophilic. The process is of mild conditions, little injury to the cotton, energy conservation and more friendly to the environment, and overcome the many shortcomings of alkaline scouring. However, bio-scouirng is not as effective as alkaline scouring in removing stubborn impurities——cotton-seed hulls, which has become the largest obstacle to the commercialization of cotton bio-scouring. Based on the predecessor research results of the cotton-seed hulls structure and chemical composition analysis, this paper took cotton-seed hulls as the goal, emphatically investigated three single enzymes of the xylanase, cellulase and pectinase and compared the degradation effect of the cotton hulls shell by the three single enzymes and blends with each other, emphatically from the properties of the enzymes. And then the maximum rate of degradation of cotton-seed hulls is related with the kind of enzyme is found. Furthermore, the mechanism of the bio-degradation of cotton seed hulls by those enzymes is discussed. According to the above experimental results, we took Fusarium oxysporum as the experimental object and produced the complex enzyme that suitable for cotton bio-scouring by adding different inducers, different concentration and different kinds of available source of carbon. In addition, complex enzyme produced by Trichoderma reesei submerged fermentation was dealt with the selective adsorption processing method and used in the cotton fabric pretreatment based on the research of our lab and get on cotton the cellulose of ideal remove impurities especially the cotton seed shell effect. The main research results are as follows:1. the optimum pH, optimal temperature, pH stability and temperature stability of the cellulase, pectinase and xylanase were studied from enzyme characters, The optimum conditions for them were investigated and highest cotton-seed hulls removal is 5.8% for dilution of five times the xylanase (32.8 U/ml), and 2.2% and 1.4% of the cotton seed hulls removal was got by two times diluted the cellulase and pectinase. In addition, the cotton seed hulls removal was increased to 7.5% by blending with them.2. The Fusarium oxysporum was taken as research object, with glucose and glycerin for available carbon source respectively, adding the cotton seed hulls, ramie, xylan to the culture medium to induce it prepare complex enzyme which xylanase primarily, and studied the enzyme production process. The study results showed that, glycerin as available carbon source is obviously better than with glucose as available carbon source for inducing Fusarium oxysporum to produce complex enzyme. Adding content that is 1%(v/v) glycerin and 2%(w/v) the cotton seed hulls to the medium, The Fusarium oxysporum produce multiple enzyme effect best, including xylanase, cellulase, pectinase enzyme's highest activity is 2.7 U/ml,0.35 U/ml,0.025 U/ml in turn. 0.5% glycerin+2% xylan enzymes in combination to induce enzyme was inferior and xylanase, cellulase, pectinase highest activity are 2.2 U/ml,0.36 U/ml,0.12 U/ml. But three enzymes' highest activity will not appear at the same time in fermentation. Ramie induction effect is the worst.3. the optimum temperature, optimum pH, thermal stability and pH stability of complex enzyme produced by Fusarium oxysporum was Studied. The results showed that xylanase of compound enzyme thermal stability is not good when the temperature more than 45℃, keep heat preservation at 45℃one hour, residual enzyme activity remains only 40% or so, which limits compound enzyme hydrolysis the cotton seed hulls directly.4. If cellulase activity too high, it will be damage to cotton fiber. In view of the above statement ,this paper take the complex enzyme prepared by Trichoderma reesei as experimental object, and investigate microcrystalline cellulose and CMC selectively absorbing cellulase to prepare composite enzyme of low cellulase. The results showed that, microcrystalline cellulose has good adsorption of cellulase, while have a bad absorption of xylanase. When the addition amount is 0.05 g/U, adsorption time is 15 min, microcrystalline cellulose to cellulase and xylanase adsorption rate reach to 28.5% and 0.6%, respectively. But as to the CMC, The result is just the reverse, its adsorption on xylanase better than the adsorption on cellulase, when addition amount is 0.05 g/U, adsorption time for 30 min, CMC absorption rate on cellulase and xylanase was 14% and 43% respectively. Furthermore, from the curve of the adsorption time-adsorption rate, we find that microcrystalline cellulose absorption on complex enzyme is a dynamic adsorption process.5. The cotton seed hulls removal and the damage of cotton by the bio-scouring and traditional alkaline scouring were compared. The results showed that, on the cotton seed hulls removal rate and breaking strength, bio-scouring is better than traditional alkaline scouring, but on the white degree and Capillary effect, traditional alkaline scouring is better than bio-scouring. Moreover, it has greatly improved the cotton cloth damage and Capillary effect that applying the crude enzyme after absorption to cotton bio-scouring, after bio-scouring, the cotton seed hulls removal rate increased from the original 33% to 38%, and Capillary effect from 7 rise to 7.4, white degree have 5% increase, breaking strength from 195 N increased to 276 N. After bleaching, the cotton seed hulls removal rate is 84%, Capillary effect is 9.1, the white degree is 77.8%, and the breaking strength is 255 N. |
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