Application and research progress of biological enzymes in pulp and paper making process

Enzymatic deinking is mainly based on enzyme attack on ink or fiber surface. Lipase and esterase can effectively degrade plant oil-based ink, while amylase, lignin degrading enzyme, pectinase, cellulase and hemicellulase can directly change the linkage of ink ion attachment on fiber surface area, promote ink separation and remove ink by washing. Compared with chemical deinking, the physical properties, whiteness and freedom of pulping are very high.

3. Research progress of biological enzymes in the process of pulping and papermaking

3.1 Modification of cellulase

In the study of the application of biological enzymes in pulping and papermaking, it was found that the degradation process of cellulose would be affected not only by the structure of cellulose itself, but also by the adsorption of cellulase and the inhibition effect of product. It can be seen that the cellulose degradation process is a relatively complex multiphase reaction system. For example, when commercial cellulase preparation L is selected to act on waste pulp at a low dose, the freeness of pulp will be increased to a certain extent, and the mechanical properties will not be lost. Cellulase modification can not only improve the water filtering performance of pulp, but also improve the paper forming performance of pulp. When cellulase is used for pulp treatment, the filter water of the pulp will be significantly improved, because the connections between the fibers in the pulp become tighter, so that cellulase is difficult to penetrate them to degrade cellulose molecules. Under the premise of maintaining the strength of the pulp, the water filtering performance of the pulp can be significantly improved. In addition, under the action of enzymes, the performance of the fiber will also change to a certain extent, because cellulase will cause certain corrosion, peeling or fine fibrosis on the surface of the fiber, resulting in changes in the performance of the paper. It is found that the complex cellulase can effectively improve the smoothness of paper and improve the printing performance of paper.

3.2 Application of lignin-degrading enzyme modification

Laccase can be said to be one of the most widely used enzymes in the pulping and papermaking process, so the application of laccase is mainly concentrated in the modification of paper with higher lignin content. First of all, laccase can well improve the physical properties of high yield pulping, because it has been found that laccase modified pulping is not only closely related to its own properties, but also has a great relationship with the lignin content in the pulp. In other words, the higher the lignin content in the pulp, the more significant the changes that laccase can bring to the properties of the pulp, so this property can be fully utilized to improve the binding properties between fibers [4]. Secondly, laccase often requires oxygen to participate in its action, and it is also accompanied by intermediaries involved in cyclic oxidation. When laccase exists in a small molecule mediator, its oxidation range is higher than the reaction range when laccase exists alone, and it was also found in the study that the increase in the range of small molecule mediator substances will increase the application range of laccase, which indirectly indicates that the application prospect of laccase is very broad.