| Bleaching is a necessary stage in the papermaking, also is one of mostserious pollution stage for the enviroment, especially for the water environment. So, itis important to take supplementary means for improving bleaching performance ofpulp and bleaching efficiency of drugs.Ionic Liquids is a green solvent in the last few decades, it has someadvantages, such as thermal and chemical stability, almost no vapor pressure, highionic conductivity. Ionic Liquids has been quite adequate research and application inthe cellulose field. Ionic Liquids pretreatment can improve swelling of cellulose andhas an effect of cellulose crystalline, in orde to improve the bleaching performance.The main aim of this paper is researching on sulfate pulp and mixed officewasted paper(MOW) were pretreatmented by1-allyl-3-methyl imidazolechloride(AmimCl) and1-butyl-3-methyl imidazole chloride(BmimCl), and thenbleached by hydrogen peroxide and chlorine dioxide. To give the purpose ofimproving the bleaching efficiency and brightness.The initial synthesizing technology of AmimCl and BmimCl is researched.The optimum conditions of AmimCl synthesizing are: the ratio of chloropropene andN-methyl sulfonated1.2:1, response time8h, temperature55℃. The yield of AmimClin optimum conditions is86.52%. The yield can reach83.24%with microwaveheating for2h, so the microwave heating can greatly increase the reaction rate ofIonic Liquids. The optimum conditions of BmimCl synthesizing are: the ratio ofchlorobutane and N-methyl sulfonated1.4:1, response time24h, temperature80℃.The yield of AmimCl in optimum conditions is78.85%. The yield can get to77.65%with microwave heating for4h.The change of fiber morphology, crystallinity and chemical groups of ligninafter Ionic Liquids pretreatmented is researched. Fiber is fibrillation and swelled afterpretreatmented, Ionic Liquids not only take effect of non-crystalline regions, but alsocrystalline regions. The crystallinity of fiber reduces8.74%after AmimClpretreatmented, reduces12.66%after BmimCl pretreatmented. Analysis the lignin inthe pulp by NMR phosphorus spectrum, aliphatic hydroxyl reduced by11.89%and11.54%after AmimCl and BmiimCl pretreatmented, the total phenolic hydroxyldecreased by20.47%and18.13%, carboxyl increased by18.72%and28.09%.The optimal pretreatmented conditions for hydrogen peroxide and chlorine dioxide bleaching are researched. For hydrogen peroxide bleaching, the optimalpretreatmented conditions of AmimCl are: pulp moisture12%, ILs consumption1.2mL/g, temperature70℃and time30min, compare to the unpretreatment pulp, thebrightness increased2.50%ISO with pretreatment after bleaching, tear index and burstindex increased6.36%and3.22%respective. The optimal pretreatmented conditionsof BmimCl are: pulp moisture3%, ILs consumption1.2mL/g, temperature60℃andtime40min, the brightness increased3.68%ISO with pretreatment after bleaching,tear index and burst index increased3.63%and1.75%respective. For chlorinedioxide bleaching, the optimal pretreatmented conditions of AmimCl are: pulpmoisture8%, ILs consumption1.0mL/g, temperature60℃and time20min, compareto the unpretreatment pulp, the brightness increased5.95%ISO with pretreatment afterbleaching, tear index increased4.55%and burst index reduced5.26%. The optimalpretreatmented conditions of BmimCl are: pulp is over dry, ILs consumption1.2mL/g,temperature50℃and time40min, the brightness increased6.75%ISO withpretreatment after bleaching, tear index and burst index increased2.27%and2.02%.The effect of deinking and bleaching property of MOW by ILspretreatmented is researched. The residual ink reduced by7.90%and3.20%afterfloatation deinking, compare to the unpretreatmented, brightness increased by4.11%ISO and1.70%ISO after hydrogen peroxide bleaching. |
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