Study On Improving Properties Of APMP By Laccase/Mediator Combined With Pectinase

Alkaline hydrogen peroxide mechanical pulp (APMP) is a kind of high yield pulp(HYP) which is developed on the basis of bleaching chemical thermal mechanical pulp(BCTMP). APMP has many advantages such as high yield, good strength, less pollutionload, and low energy consumption. During the process of APMP, pulping and bleachingcan take place at the same time which can save the equipment investment. In recentyears APMP has rapid developed, due to the attention of pulp and paper industryworldwide.Compared with the bleached chemical pulp, APMP contained high fine fibercomponent and more dissolved and colloidal substances (DCS) which can affect thestrength of the pulp, whiteness, and filtration performance, etc. In order to improve theperformance of the APMP, we can modify APMP through the chemical and biologicalmethods. Chemical methods are being washed out gradually due to the shortage ofnatural resources and aggravate problem of environmental pollution. Biological methodis arising people’s attention. Laccase is a kind of polyphenol oxidase with copperbearing, which can oxidize polyphenol, aniline and so on. The system of laccase andmediator can overcome the weakness of laccase of low redox potential. In the conditionof oxygen, the system can increase the ability of degrading lignin. Pectinase is amultienzyme complex that can degrade pectic substance. This paper studies thesynergism of laccase/mediators and pectinase to improve the characteristics of theAPMP.Aspen APMP was treated with laccase/mediator together with pectinase, and thenwas refined in PFI to different beating degrees. The water retention value, physicalproperty and optical property were analyzed. The optimum condition of pretreatmentwas studied. The results showed that treating APMP with laccase/mediator andpectinase before beating could reduce beating energy comsumption. The inter-fiberbonding and physical property of APMP was improved, but the whiteness, bulk, andwater retention value were reduced. Moreover, the softness of the fibers improved andtheir refining property increased. The fiber was less cut, and the average fiber lengthwas longer and content of fine was less, compared with control pulp.The characteristics of DCS in aspen APMP was analyzed with different analyticalmethods. The UV analysis showed that most of the lignin in DCS was in the form of dissolved lignin. The results of GC-MS analysis indicated that the carbohydrates inDCS were mainly composed of xylan, glucose, arabinose, galactose, mannose, andglucuronic acid, and the content of xylan was the highest among the dissolvedcarbohydrates. The cationic demand of DCS in APMP decreased obviously after treatedwith pectinase. The turbidity and the content of lignin decreased after treatment withlaccase/mediator. The decrease of the CD of DCS verified the degradation ability ofpectinase and laccase/mediator on lignin. Treated APMP with laccase/mediator andpectinase before beating could reduce the amount of DCS, lower the load of the wastewater.