Kratf Pulping And Oxyen Delignification Of Finns Massoniana With Prehydrolysis

The kraft pulping and oxyen delignification of Pinus massoniana withprehydrolysis, which used for the preparation of viscose fiber, were studied,optimized, and also compared with the traditional KP process. It was obtained that thecontent of pentoses was lower than 3% when the hydrolysis P factor was 700. Theoptimized cooking conditions for kraft pulping were alkali amount 22%, sulfidity25%-30%, H factor 1500-1600. The kappa number and viscosity and yield of thescreened pulp of Pinus massoniana prehydrolized kraft pulp were lower than the KPpulp. The optimal conditions of oxygen delignification of Pinus massoniana kraft pulpwith prehydrolysis were alkali 3%, temperature 100℃, reaction time 60min, oxygenpressure between 0.5MPa and 0.6MPa, MgSO₄charge 0.2%. The oxyendelignification rate of the kraft pulp with prehydrolysis was 22.39% higher than that ofthe KP pulp, but the viscosity reduced rate was 6.3% lower than that of the KP plup.The oxyen delignification rate of Pinus massoniana kraft pulp with prehydrolysis wasincreased with prehydrolysis P factor, but the change of viscosity was very little.The power law of delignification model was used to study kinetics ofdelignification of Pinus massoniana kraft pulp with prehydrolysis. Delignificationreaction order in lignin, the concentration of NaOH and oxygen pressure was 4.42,1.04 and 0.76, respectively, and the activation energy was found to be 31.45KJ/mol.According to HexA content and infrared spectral analysis to study oxygendelignification mechanism.The content of HexA of Pinus massoniana prehydrolysiskraft pulp that before and after oxyen delignification was lower than KP pulprespectively, and the difference of HexA content of the two pulp could effect theresults of oxygen delignification rate.The FT-IR showed that the absorption peak at1279cm^-1was decreased, and the abata degree of Pinus massoniana kraft pulp withprehydrolysis before and after oxyen delignification was significantly greater than theKP pulp, indicating that the content of guaiacyl was reduced, which cased the lignindegradation, and also indicating that the lignin of Pinus massoniana kraft pulp withprehydrolysis was easy removal than the KP pulp. After oxygen dilignification, theabsorption peak at 1163-1165cm^-1, 1112cm^-1and 1057-1058cm^-1of Pinus massonianakraft pulp with prehydrolysis and the KP pulp were all decreased, but abata degree ofPinus massoniana kraft pulp with prehydrolysis before and after oxyen delignification was little, indicating that the cellulose had certain degree of degradation during oxyendelignification, but the degradation of the cellulose of Pinus massoniana kraft pulp withprehydrolysis was less.