Performance And Pulp Properties Of CTMP Bleaching System Improved By Laccase/ Amboceptor

Bio-bleaching is the process that using of microorganism or enzyme working with the pulp to achieve delignification or to facilitate delignification and enhance brightness or bleachability. Currently, lignin-degrading enzymes is considered as one of the most application prospect laccase, is the most popular, and most notable progress in pulp bleaching researching process. Mediator is one of biological electron carriers in biological bleaching LMS. As a small molecule, overcome the disadvantages of low reduction potential and only oxidative degradation of phenolic lignin structural units in the apply Laccaseto bleach.the mediator avoid steric hindrance formed by the protein macromolecules degrading lignin. The presence of mediator makes oxidation of laccase to Non phenolic lignin been possible. The main problems in laccase mediator system are: 1) because of the chemical reaction, part of the mediatorloss of activity and catalysis, thereby increasing the amount and cost; 2) synthetic mediator has a complex and expensive process;3) mediator has a poor soluble touch to the using in bleach; 4) Many mediator contain toxic, hazardous to human health.This paper researched laccase mediator system processing to improve performance and to CTMP pulp bleaching properties. There are about four main research areas:1) inquiring the process of laccase modified CTMP pulp, and to analyze the performance of the fiber surface; 2) the impact of lignin structure treated by laccase/mediator system to CTMP;3) changes of molecular weight in lignin modified by laccase process; 4) changes of lignin structurein CTMP pulping process.It was found that under optimum conditions, compared with the control pulp, the brightness of laccase treated CTMP decreased, the tensile index and tear index were improved, thickness, the mean length, weight both length and weight average length of the pulp fibers has increased two small margin and the Optimal dosage is 2u/g, the best time is 60 min. Lignin treated by LMS hydroxyl and methoxyl content is reduced. Syringyl lignin structure was significantly reduced, guaiac wood-based ratio and lilac base unit has increased.residual lignin number average molecular weight decreased after laccase treatment in CTMP, But the mass-average molecular weight can be observed increased significantly. In CTMP pulping, the lignin aliphatic phenolic hydroxyl and hydroxyl content decreased, the amount of carboxyl group was increased in the lignin significantly. Contract Syringyl, phenolic hydroxyl group for the amount of phenolic hydroxyl groups had significantly reduced.