Of Naoh-aq / The O <sub> 2 </ Sub> Two Oxygen Paragraph In Cooking Silicon Transfer Characteristics Of The Simulation Study

Wheat straw is one of most important non-wood fiber raw materials for China's papermaking industry. Silicon in the wheat straw black liquor is a key obstacle to the chemical recovery of the black liquor. NaOH-AQ/O2 two-stage cooking process is a potential process for environmental friendly wheat straw pulping. This paper deals with the silicon transferring properties between the fibers and water phase in simulation alkaline O2 cooking by adding given Na2SiO3 to the O2 cooking system. The purpose is to guide the NaOH-AQ/O2 two-stage cooking process toward industrial application.The main factors that influence the transfer between fibers and water phase during the oxygen-alkali cooking are pH, oxygen pressure, temperature and so on. The main results obtained are following:1. The pH value has an important influence on silicon transferring between the fibers and water phase in the oxygen-alkali cooking stage. Under the fixed oxygen pressure, temperature and other conditions, the silicon retention on the fibers increase with the decrease of alkalinity in the system.2. The oxygen pressure has impact on silicon transferring between the fibers and water phase in the oxygen-alkali cooking stage. Under the given pH, temperature and other conditions, the silicon retention on the fibers increased with the increase of oxygen pressure in the system3. The temperature has an obvious impact on the oxygen-alkali steam boiling stage. Under the fixed pH value, oxygen pressure and other conditions, the silicon retention on fibers increase with the increasing of temperature while the silicon concentration in the water phase decrease.The simulation test indicated that high silicon content in the fibers was 1.49%, a low silicon concentration was 0.05g/L in the water phase when the oxygen pressure was 0.50 MPa, pH was 5 and the temperature was 100℃.4. After O2 cooking, the addition of PEO has an important impact on the silicon transfer between the fibers and water phase. The beneficial parameters to the silicon retention on the fibers, up to 3.8% silicon based on the fibers (o. d), were pH, 9; PEO dosage, 0.06%; the pulp concentration, 3.0%.5. It is observed that there are silicon gels on the fiber surface by SEM and showed that the silicon can be transferred onto fibers from cooking liquor by oxygen-alkali cooking.