Study On The Strength Improving By The Ways Of Laccase&Laccase/Natural Mediator Systems Treatment

With the increasing economic development and import and export trade of our nation, the need of corrugated containers increased. National old corrugated containers pulp(LOCC) is the based material of our national corrugated containers, whose quality is of a sort, but the content is greatness, therefor, finding an environmental method to increase the National corrugated containers is necessary.Reinforcing technology of national old corrugated containers pulp (LOCC) with laccase, laccase/cellulose system, laccase/natural mediator system and laccase/white water system was studied. The mechanism of pulp properties improvement with laccase was analyzed by modern analytical technology, such as gel permeation chromatography (GPC), scanning electron microscope (SEM) and fiber-tester. In addition, the strength increasing mechanism was researched with unbleached kraft pulp.From the reaseach for LOCC treated with different system, we found that the the best optimized conditions of laccase treatment:laccase dosage24U/g, consistency3%, pH6.0, temperature45℃, reactive time2h in the air condition. The dry tensile strength increased by11.5%, the wet tensile strength increased by12.2%, the dry ring crush strength increased by7.5%, the wet ring crush strength increased by20.61%; The optimized project of laccase/cellulose system is laccase2h+cellulose(Fibercare D)1h. In this situation, the dry tensile strength increased by22.30%, the wet tensile strength increased by24.02%, the dry ring crush strength increased by4.88%, the wet ring crush strength increased by21.15%. In research Three kinds of phenols, namely gallic acid, syringal alcohol and ferulic acid, were selected as laccase natural mediator. It was shown that the condensation reaction of natural mediators occurred by laccase catalytic oxidation; After the LOCC pulp were treated by laccase/natural mediator system, fibers surface became much more smooth; deposits and films on the fibers were observed. The wet tensile strength increased by8.96%,8.28%,8.96%, the wet ring crush strength increased by29.88%,45.98%,50.57%; The research of laccase/white water(LOCC white water&APMP white water) system shows that the laccase/LOCC white water is better, the dry tensile strength increased by9.99%, the wet tensile strength increased by26.99%, the dry ring crush strength increased by10.47%, the wet ring crush strength increased by24.89%.From the research with unbleached kraft pulp we found that under the treatment of laccase/p-Coumaric acid natural mediator system, the KAPPA number increased by10.76%, the fiber coarseness increased by10.6%, deposits and films on the fibers were observed on the surface of fibers, the wet tensile strength and the wet ring crush strength increase obviously; From the research of different lignin models we found that the syringaldehyde is the best natural mediator and then is the p-hydroxybenzaldehyde, the vanillin is the last one.