The Masson thermomechanical pulp (TMP) which obtained from the first stage refiner was pretreated with xylanase and then was refined with PFI refiner. The effect of enzyme-aided refining on the wet-end chemistry of Masson TMP including beating degree, zeta potential, dissolved charge and filler retention was studied. And the bleachability of enzymatic refined pulp was also evaluated. This research is of great significance for energy saving, paper machine runnability and paper quality improvement and biotechnology application in pulp and paper manufacturing. The impact of enzymatic charge and treatment time on wet-end chemistry and bleachability of pulp were mainly conducted. The results showed that the enzymatic pretreatment increased the beating degree, zeta potential, dissolved charge and filler retention. At the xylanase dosage of 0.3 AXU/g (o.d. pulp), compared with the control sample, the beating degree, zeta potential, dissolved charge and filler retention increased respectively by 18.8%, 17.5%, 10% and 19.6%. And at this enzyme charge, the extension of pretreatment time also increased these wet-end chemistry parameters above. In addition, xylanase pretreatment could improve the bleachability of Masson TMP. The tensile index, the tearing index and the brightness increased 2.3 N.m(2)/g, 0.19 in N.m(2)/g and 1.3%ISO, respectively, compared with the control sample at the xylanase charge of 0.3 AXU/g (o.d. pulp). Meanwhile, the prolongation of pretreatment time could increase the strength properties and the brightness of paper. When the pretreatment time was fixed at 30 min, the tensile index, the tearing index and the brightness were increased by 2.79 N.m(2)/g, 0.33 mN.m(2)/g and 5.5%ISO with respect to the control samples.
