| With the strengthening of environmental protection concept and the rising demand forecological products, the development and utilization of natural fibers has become an importantsubject. It still remains a breakthrough about the preparation of natural fibers. At present, mostnatural fiber preparation process used chemical agents for response to the technical route, whichnot only had such problems as high cost, time consuming and fiber damage, but also produced lotsof waste and pollution that was harmful to the environment. In the low carbon economy era, weshould pay more attention to the environmental protection. Thus this method for natural fiberproduction process has been difficult to adapt to the increasingly fierce market competition and thehigh speed development of science and technology. Therefore, it has become necessary to explorethe preparation technology which has low pollution, low energy consumption and isenvironmental.In this study, one of the lignin degradation enzymes, laccase, was used to explore thepreparation process of the mulberry fiber which is included in natural fibers. First of all, thechemical composition of mulberry fiber was systematically analyzed. In order to explore theoptimum production process of the mulberry fiber, the chemical composition of the fiber wascompared with that of other natural fibers. On this basis, respectively, the study set severalresearches on mulberry fiber included laccase individual processing, laccase-media treatment,enzyme-chemical treatment and compounded enzyme treatment. The conclusion shows as follows:1. Within the scope of the optimal enzyme activity, the main factors influencing the ligninremoval efficiency were enzyme concentration and reaction time. Relatively, temperature and pHvalue didn’t make much difference influence. The lignin removal efficiency varied considerablywithin2hours, the change after two hours became steady. Due to the influence of other pectin inmulberry, laccase individual processing cannot fully meet the ideal requirements of fiberpreparation process, the lignin removal efficiency of whom was only50%.2. The research on laccase-mediator system process for removing lignin showed that: Asmediators played a mediating role in the process of lignin degradation with laccase, the lignin removal effect was relatively better than that of laccase individual processing. Also, the ligninremoval efficiency increased with the increase of mediator concentration.3.The results of enzyme processing after pre-acid and pre-alkali treatment concluded that:when effectively removed or reduced the pectin in the mulberry before enzyme treatment, theremoval effect of lignin would be better. The residual lignin of enzyme treatment after pre-acidprocessing was3.47%, and the residue rate was24.73%. The residual lignin of enzyme treatmentafter pre-alkali processing was3.86%, and the residue rate was19.06%.After considering theinfluencing factors of lignin, the study adopted pretreatment-enzyme treatment-chemicalprocess as the experiment scheme. The optimal process parameters were as follows: acidconcentration of1g/L, enzyme processing time of3h, enzyme concentration of20%, alkaliconcentration of9g/L. This method lead to the result that residual lignin of fiber was2.31%, andthe removal rate was76.97%.Also, the residue rate had reduced to9.36%.4. Pectinase and xylanase compounded with laccase, which was compared with pectinase andxylanase individual processing. These two kinds of enzyme treatment were used to deal withmulberry fiber. The result shows that the lignin removal efficiency of compounded enzyme washigher than that of any individual processing. The main influencing factors were dosage of thecompounded enzyme and enzyme processing time. Lignin removal efficiency had reached70.39%by the compounded enzyme of laccase and pectinase,78.83%by the compounded enzyme oflaccase and xylanase. Compared with enzyme-chemical treatment process, this kind of processcould receive long fiber length and relatively coarse fineness. |
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