Study On The Process And Mechanism Of Steam Explosion Pulping Of Bagasse

Due to the more serious pollution, the shortage of plant fiber and energy resources, many studies have been conducted to the new pulping technology of high yield, lower energy consumption and lower pollution. The steam explosion pulping (SEP) technology has the advantages of high yield, high production efficiency, high fiber strength, lower energy consumption and lower pollution, so it has been developed as a advanced high yield pulping technology. The main research focused on the optimal explosion process and the effect of process parameter on the chemical constitutes of explosion pulp. The bleaching possibility of explosion pulp and the characteristic of effluent were also studied. Simultaneously, the advanced analytic technology of SEM, X-ray diffraction spectrum, UV spectrum, IR spectrum as well as XPS were used to analyze the microcosmic of explosion pulp. The results of the research are as following:1. Orthogonal test and the validate experiment were performed to achieve the optimal explosion conditions: NaOH charge 2.0%, Na2SO3 charge 2.0%, AMS charge 0.1%, liquor to wood ratiol: 4.0, explosion pressure 1.4MPa. All of the physical index of corrugating base board made from the explosion pulp were higher than the A grade corrugating base board.2. There were some influences on the cellulose, hemicellulose and lignin content of explosion pulp by the explosion parameter. It also showed that parameter of NaOH charge and explosion pressure were the main influencing factors.3. The brightness of unbleached explosion pulp is lower. So it was hard to bleach. After the two-stages bleaching of P-P or H-P process, the latest brightness could not reach to 40%(ISO).4. The SEP was a lower pollution pulping technology, and its pollution load was approached to the CTMP technology, but its pollution load was lower remarkably than the Semichemical Pulping technology.5. The SEM analysis showed that explosion treatment lead to many breakage of fiber as well as S1 and S2 of wall cell. The fiber bundle became separated, soft and curling. It also indicated that the separating of fiber bundle has a close relationship with explosion pressMland the added chemical for pretreatment.6. The X-ray diffraction spectrum analysis showed that the relative crystallinity of cellulose treated by explosion was increased, while the absolute crystallinity was decreased. The reasons for these could be that hemicellulose was degraded partially after explosion.7. In the UV spectrum analysis of wash waste, there is a strong peak in wavelength of 280nm and this data provided evidence that the lignin was destroyed in explosion treatment. 8 The IR spectrum analysis showed that explosion treatment could only change the intensity of absorption peak partialy and the main chemical structure of lignin has not changed yet. It also indicated that the relative absorption intensity of cellulose peak increased and the characteristic absorption peak of hemicellulose was weakened remarkably.9. The XPS analysis showed that the O/C ratios on the fiber surface increased and the peak area of C\ decreased after explosion. It indicated that there were more carbohydrate and fewer lignin and extract on the fiber surface. Moreover, the increase of S/C ratios indicates that there was a higher lignin sulfonation degree on the fiber surface, and this is a main reason leaded to higher paper strength.