Study On Properties Improvement Of AOCC Pulp Through Laccase Catalyzed Oxidation

In various new techniques of the pulp and paper industry, the application of the enzyme has advantage and potential.Laccasec can oxidize the lignin so it is subjected to concern mostly in recent years.Laccase (EC 1.10.3.2) is a kind of multi-phenol oxidase. It can oxidize polyphenol, multi-ammonia benzene etc. Laccasec with the aid of oxygen and mediator can make lignin degradation, applying in the bleaching of pulp. In addition, the more important aspect is that Laccasec can make lignin polymerization , improving the bonding of fibers, applying in the manufacture of fiberboard and the improvement of the property of high lignin content pulp.The American Old Corrugated Containers(AOCC) was treated with laccase NS 51003 in this thesis. Improving of pulp property by laccase modification was studied.At the same time, influence of white water recycle on the laccase modification was studied. In addition laccase-treated fiber surface and handsheet transaction were viewed by SEM.This thesis is concern with an interdiscipline research subject. The research results are beneficial to environmet protection and have potential prospect of application.The AOCC was treated with laccase NS 51003 in the experiments. The results showed that wet ring crush compression strength(RCT) and wet tensile strength of AOCC treated with laccase increased significantly compared to control handsheet. It was found that the optimum conditions for laccase treatment were: the charge of laccase 16μ/ g pulp, pulp consistency 5%, pH 7.3 , temperature 25 ℃, reaction time 1h .Compared with the control, the wet-strength could be increased by about 35% after the laccase treatment. The ideal effect of laccase treament could be abtained by blowing air in the system.The wet ring crush strength and wet tensile strength of AOCC pulp would be further improved by adding mediator MS[methyl syringate] to the laccase and forming the laccase/mediator systemWith further closed water circuit in the papermaking industry, there will be more and more anionic trash in the system ,causing a lot of problem. We first did some research about the effect of white water on the laccase treatment. It was found that not only laccase treatment could improve the wet strength of AOCC, but also it would reduce the content of anionic trash in the white water, So it could notable decrease the cationic demand. Undoubtedly, this would be a new approach in tackling the anionic trash problem. In contrast with the PAE, laccase could improve the AOCC wet strength when the white water recycled.According to fiber surface analysis by SEM, obviously, it was found that the...