蔗渣低碱耗氧碱蒸煮中碳水化合物降解及其抑制机制的研究

The degradation of carbohydrate in alkali oxygen cooking is serious and it lead to the high consumption of alkali. To reduce the degradarion, bagasse, which is the agricultural solid residue, would be used as material of alakli-oxygen cooking, and the main contents of this study are as follows: To begin with, the oxygen radicals are characterized and controled to promote the slectivity of carbohydrate and lignin in the alakli-oxygen cooking process,then the dissipate alkali could be control or decreased.Secondly, according to analysis on the cell parameter of crystal structure in fiber super-molecular structure, the variation and influence essential factors of fiber super-molecular structure in alkali-oxygen cooking would be determined. In addition, the topochemistry in the process of fiber liberation wiil be studied to find the inhibition method of carbohydrate degradation. At last, the components and fiber super-molecular structure of bagasse material would be controled by wet storage with TCF bleaching waste liquid. Then the alkali oxygen pulping system with low consumption of alkali would be builded by the combinnation control of material and factors in the pulping process. In a word, the results of this research could deveolp and promote the basic theories of alkali oxygen cooking with low consumption of alkali, and the energy saving and clean requirment of alkali oxygen cooking of bagasse could also be promoted into higher platform with certain theoretical foundation.

本项目针对氧碱蒸煮过程中存在的碳水化合物降解严重及由于碳水化合物降解引起的高碱耗问题，以农业固体废弃物- - 蔗渣为原料，通过对氧碱蒸煮过程中含氧自由基的表征和控制，提升氧碱蒸煮过程中木素和碳水化合物的选择性，解决或降低蔗渣氧碱蒸煮过程中由碳水化合物降解引起的无偿碱耗问题；分析纤维超分子结构中的晶体结构和晶胞参数，明确纤维素超分子结构在氧碱制浆过程中的变化和影响要素，解析纤维素分离过程中的局部化学，寻求抑制碳水化合物降解的方法；采用节能洁型TCF漂白废液介入蔗渣湿法堆存调控，优化蔗渣原料的化学成分、纤维超分子结构和过渡金属离子种类及其含量，使原料、氧碱蒸煮过程要素控制相结合，创制预处理低碱耗氧碱蒸煮优化体系。本课题的研究成果对发展、提升低碱耗氧碱蒸煮反应基础理论，将蔗渣氧碱蒸煮的节能清洁化要求推向更高的平台具有一定的理论支持。

氧碱制浆是一种由氧碱漂白派生出来的极具潜力的环保型制浆技术，研究和控制氧碱制浆过程中碳水化合物降解引起碱耗高问题，对解决氧碱制浆技术工业化实施的关键问题和丰富氧碱制浆理论有重要的意义。本项目通过对蔗渣氧碱蒸煮过程中含氧自由基的表征和控制，研究羟基自由基和超氧阴离子自由基及其产生曲线对氧碱制浆过程中木素和碳水化合物降解的影响，明确了羟基自由基在氧碱蒸煮初期的脱木素效率高并脱木素选择性好的特性，超氧阴离子自由基在氧碱蒸煮后期起到补充脱木素并对碳水化合物影响少的特性。在氧碱蒸煮前期，因小分子木素和非结晶碳水化合物的溶出，碱消耗速度快，纤维的孔隙率增加；通过TCF漂白废水介入蔗渣湿法堆存调控，控制原、物料的化学成分、纤维超分子结构，提高脱木素的靶向性，可有效提高制浆效率和降低非结晶区碳水化合物降解引起的碱耗高问题。在氧碱蒸煮的中后期，纤维原料以纤维素为主，因羟基自由基氧化电势高，造成纤维降解严重和结晶度降低；可通过添加自由基控制剂，调节脱木素选择性好的超氧阴离子自由基的比例，促进残余木素的选择性脱除，可有效提高氧碱制浆性能，降低结晶区碳水化合物降解引起的碱耗高问题。本项目通过TCF漂白废水介入蔗渣湿法堆存调控和氧碱制浆过程中含氧自由基调控相结合，实现了低碱耗氧碱制浆体系的优化。