Modification And Compounding Of Biological Enzymes And Their Application In Papermaking Process

Waste paper fibres such as waste corrugated pulp(OCC pulp)suffer from fibre decay,reduced water filtration performance and lower paper quality in the recycling process.In this paper,a study was conducted on the modification and compounding of biological enzymes to improve pulp fibre quality and paper properties.The effect of four single enzymes on the physical properties of pulp fibre quality and finished paper was investigated by using the fibre quality analyser and microcomputer tensile strength tester.The average length of cellulase increased by 0.11 mm at a dosage of 7.5 U/g(absolute dry pulp),with the greatest reduction in the content of fine fibres,the best water filtration performance and a 10.18% increase in the ring pressure index of the paper.At 22.5 U/g of xylanase,the pulp pulping degree decreased from 32°SR to25.3°SR,with an increase in fibre swelling,a 0.5 μm increase in fibre width and a12.6% increase in tensile index.The amount of mannan 18 U/g and the amount of pectinase 15 U/g played an auxiliary role in the fibre modification.The optimum solution for pulp treatment with the enzyme complex was obtained by combining the actual papermaking process requirements: the best water filtration performance under the conditions of 300 m L/t of enzyme complex,30°C～55°C,p H 3.0～6.0 and reaction time 30 min～50 min.In this study,the use of glutamine transaminase(TGase)to catalyze the cellulase protein to undergo its own cross-linking reaction,combined with substrate blotting,can effectively protect the enzyme activity region to improve the stability of the enzyme.The enzyme activity of the neutral cellulase solution was increased by 21.4% compared to the control when TGase was added at 10 U/m L and held at 60°C for 2 h.The enzyme activity of the TGase modified cellulase system was increased by 70.4% compared to the control when 10 m L of the blotting substrate,sodium carboxymethyl cellulose(CMC-Na),was added.The substrate blotting technique in combination with TGase increased the relative enzyme activity of the modified cellulase by 91.8% when held at50°C for 2 h and by 100.7% when held at 60°C for 2 h.Cellulase,the core enzyme of water filtration enzymes,is modified to improve the stability of the enzyme while reducing damage to the fibre from overdosing.The modified cellulase improves the specific surface area of cellulose with a 35.8% decrease in average fibre pore size when substrate imprinting technology and TGase are used in combination.The modified complex enzyme improved the paper tensile index and ring compression index by 16.5% and 23.1% respectively compared to commercial water filtration enzymes.During the corrugated raw paper production process,the addition of300 m L/t of the compound enzyme in the good pulp pool shortened the waterline distance by 2 m and resulted in steam production cost savings of approximately 9.47%.