Use of Cellulases in Modification of Simao Pine Bleached Kraft Pulp Fibers for Improved Beatability

摘要

Refining is a papermaking process that is well suitble for creating desirable structural changes in the fiber cell wall.For the development of required pulp properties,refining requires substantial energy -about 20% of the total electrical energy required for producing paper from wood.In the last few years,interest in the use of enzymes as a way of modifying fiber properties to improve the refinability of pulps has increased.The use of cellulase and hemicellulase enzymes can also help in saving energy if an enzymatic treatment stage is carried out before refining.In this paper,the effects of three kinds of cellulases-acidic cellulase,neutral ceilulase and alkaline cellulase-in enzymatic beating of Simao pine bleached kraft pulp were studied.The effects of those eellulases on the beating performances & physical properties of the bleached softwood kraft pulp in different reaction conditions were discussed.At the beginning,the effects of temperature and pH value on the activity of those three kinds of cellulases were investigated,and the enzyme activities were measured.Then,the effects of dosage of the three cellulases on enzymatic beating of pulp were evaluated.The results showed that alkaline eellulase didn't help much for pulp beating,and had somewhat adverse effect on pulp physical properties; acidic cellulase and neutral cellulase could improve pulp beating performances dramatically,and the physical properties were slightly decreased.It followed that acidic cellulase and neutral cellulase were suitable for enzymatic beating of bleached softwood kraft pulp,and could reduce energy consumption of beating process.Finally,the conditions of enzymatic treatment(temperature and pH value)of acidic cellulase and neutral ceilulase in enzymatic beating were investigated.The optimized conditions were as follows: temperature 45～50°C,pH value 4.8～5.8 for the neutral ceilulase and temperature 45～50°C,pH value 2.8～5.8 for the acidic cellulase.