湿法堆存预处理蔗渣氧碱制浆及其脱木素选择性的研究

【作者】 张宝；

【导师】 孙兵； 田超；

【作者基本信息】 昆明理工大学 ， 化学工程（专业学位）， 2019， 硕士

【摘要】 近年来,我国造纸工业和国民经济的稳步发展使得纸制品的需求量和生产量持续增长,但是制约我国造纸工业快速发展的造纸资源短缺问题一直没有解决。我国云南的甘蔗资源丰富,甘蔗榨糖后剩余的纤维原料—蔗渣,是一种良好的制浆造纸原料。因此,采用云南蔗渣资源制浆造纸具有重要的战略意义。本文以蔗渣为原料,通过湿法堆存预处理和蒸煮过程中自由基控制相结合,改善蔗渣氧碱制浆脱木素选择性。在研究湿法堆存预处理对蔗渣原料性质影响的基础上,采用自制的自由基产生体系处理湿法堆存后蔗渣氧碱蒸煮过程浆料,研究氧碱蒸煮过程中含氧自由基对湿法堆存后蔗渣氧碱蒸煮的影响,再通过氧碱蒸煮过程中添加自由基控制剂确定最优化的氧碱制浆工艺条件。通过XRD、FT-IR、SEM和BET等现代测试手段分析湿法堆存预处理后原料和纸浆的性质和微观结构,明确湿法堆存预处理与自由基控制相结合提高氧碱制浆效果的机理。湿法堆存预处理对蔗渣原料性质的影响研究表明:湿法堆存预处理过程中,由于小分子物质的溶出,纤维的孔径分布发生变化,对后续的药液渗透有着重要的影响。清水预处理蔗渣过程中,预处理时间为16天时,蔗渣纤维中大于50 nm的孔径比例最大,该蔗渣的药液渗透性能最佳。以漂白废水为堆存液时,在预处理时间为12天时,大于50 nm的孔径比例达到最大,碱吸收性能最佳,与漂白废水预处理16天样相近,漂白废水预处理改善蔗渣性质的效率更高。清水和漂白废水预处理16天的蔗渣进行氧碱制浆,其制浆效果良好,且在所得浆料卡伯值相近的情况下,漂白废水预处理后蔗渣氧碱浆的得率、黏度和白度更高。湿法堆存预处理对含氧自由基脱木素的影响研究表明:预处理后蔗渣在氧碱蒸煮升温结束时浆料以纤维束形态存在,浆料中含有大量木素,当HO·处理该浆料时,浆料中的木素大量脱除,浆料黏度略有降低,具有较好的脱木素选择性。预处理后蔗渣氧碱蒸煮保温1 h浆料已基本成浆,当HO·处理该浆料时,随着处理时间的延长,脱木素选择性降低。与清水预处理后蔗渣相比较,HO·对漂白废水处理后蔗渣氧碱浆的脱木素选择性更高。O₂^-·对于氧碱蒸煮的浆料脱木素能力低于HO·,但脱木素的选择性更高,处理后所得浆料的黏度更高。湿法堆存预处理及自由基控制剂相结合提高氧碱制浆性能的研究表明:湿法堆存预处理蔗渣在氧碱蒸煮过程中,随着蒸煮时间的延长,小于10 nm的孔径含量降低,大于等于10 nm的孔径含量增加,并随着蒸煮反应的进行纤维的结晶度呈现先上升后下降的趋势。在蒸煮开始时,加入MgSO₄保护剂对改善制浆效果更为有利;在蒸煮升温结束后加入羟基自由基抑制剂（抗坏血酸）或超氧阴离子自由基促进剂（蒽醌-2-磺酸钠）,与添加MgSO₄保护剂的蒸煮效果相比较,氧碱制浆效果更佳,可获得卡伯值相近,得率和黏度更高的浆料。更多还原

【Abstract】 In recent years,with the steady development of China’s paper industry and national economy,the demand and production of paper products increased rapidly.However,the shortage of paper-making resources has not been solved,which restricts the rapid development of China’s paper industry.Yunnan Province has abundant sugarcane resources in China.The bagasse,the remaining fiber material after sugar extraction,is a good raw material for pulping and papermaking.Therefore,the bagasse resources in Yunnan for pulping and papermaking is of great strategic significance.In this paper,the delignification selectivity of bagasse alkali-oxygen pulping was studied by combining wet storage pretreatment with free radical control during cooking.Firstly,the effect of wet storage on the properties of bagasse raw materials was investigated,the alkali-oxygen cooking process pulp of bagasse after wet storage was treated by a self-made free radical production system,then the effects of free radicals on the alkali-oxygen cooking of bagasse after wet storage were studied.Secondly,the optimized conditions of alkali-oxygen cooking reaction by adding free radical controllers in the process of alkali-oxygen cooking was discussed.At last,XRD,FT-IR,SEM and BET were used to analyze the properties and microstructures of pulp and wet storage pretreatment bagasse,and the mechanism of improving the alkali-oxygen pulping effect by combining wet storage pretreatment with free radical control was studied.The effect of wet storage pretreatment on the properties of bagasse raw materials was shown as follows:the dissolution of small molecules resulted in the change of pore size distribution of fibers,which has an important impact on the subsequent alkali impregnation.The bagasse was pretreated with tap water for 16 days,the proportion of pore diameter with greater than 50 nm was the highest in bagasse fibers,and lead to the alkali impregnation is the best.The bagasse was pretreated with bleaching waste-water for 12 days,the proportion of pore diameter with greater than 50 nm is thehighest,and resulted in the alkali absorption effect is best,the result was similar to that of the16 days.The pretreatment with bleaching waste-water was more efficient than that of tap water to improve the properties of bagasse.The alkali-oxygen pulping of tap water and bleaching wastewater pretreated bagasse is with good pulping properties,the yield,viscosity and whiteness of bagasse oxygen-alkali pulp are higher when the kappa numbers of the pulps are similar.The effect of wet storage pretreatment on delignification of oxygen free radicals was shown as follows:the bagasse was mainly as fibre fasciculus when the cooking was heated to the max temperature,and the pulp contained a lot of lignin,when the pulp was treated with hydroxyl radicals,the lignin was removed effectively,the viscosity was reduced slightly,and the delignification selectivity was good.Furthermore,the bagasse after cooked at the max temperature for 1 h,the pulp was separated well,when the pulp was treated with hydroxyl radicals,delignification selectivity decreased with the prolonging of pretreatment time.Compared with bagasse pretreated with tap water,hydroxyl radicals selectivity delignification of bagasse after bleaching waste-water pretreated was better.The delignification ability of superoxide anion free radicals was lower than that of hydroxyl radicals in the process of alkali-oxygen cooking,but its delignification selectivity and the viscosity of pulp were higher.The results of the combination wet storage pretreatment and free radical control agents to improve the alkali-oxygen pulping properties were shown as follows:with the extending of pulping time,the content of pore size less than 10 nm decreased,but the content of pore size greater than 10 nm increased,meanwhile,the crystallinity of the fibers increased at first and then decreased during the alkali-oxygen cooking.The addition MgSO₄ protective agent is beneficial to improve pulping effect when it was added at the beginning of cooking.Compared with the pulping effect of MgSO₄protective agent,it could obtain pulp with similar kappa number and higher yield and viscosity when the addition of hydroxyl radical inhibitor（ascorbic acid）or superoxide anion radical accelerator（sodium anthraquinone-2-sulfonate）were add at the max temperature for 1h.更多还原