汽爆玉米秸秆羧甲基纤维素的制备

Preparation of carboxymethylcellulose from steam exploded crop straw

秸秆是自然界中资源丰富的天然木质纤维素原料,本研究以秸秆为反应原料,采用无污染蒸汽爆破技术活化预处理,然后进行羧甲基化反应,通过反应产物理化性质的不同实现秸秆的组分分离并制备出高附加值的羧甲基纤维素。实验结果表明:制备羧甲基纤维素的最优条件为液固比(ml∶g)18∶1,氢氧化钠∶氯乙酸钠(摩尔比)为4∶3,H2O/底物(ml∶g)为1∶2,75℃反应2 h。在优化的反应条件下,从羧甲基化产物中可分离得到40.70%的羧甲基纤维素,其取代度可达0.91,而且具有低黏的性质,并利用红外图谱和1H NMR进行了分析表征;同时,还可从羧甲基化产物中分离出木质素组分,可进一步拓展其在工业方面的用途。相对于目前工业上普遍采用的α-纤维素含量较高的棉浆和木浆等反应原料,不仅原料和预处理成本大为下降,工艺流程更为简单,而且还实现了秸秆的组分分离与全利用。

Crop straw resources are abundant in nature. In this study the crop straws were used as raw material for carboxymethylation after activation by steam explosion treatment. Then the high value-added carboxymethylcellulose （CMC） was separated from other components through solvent extraction according to their different physico-chemical properties. The results indicated that the best reaction condition was that the straws were earboxymethylated at 75℃ for 2 h with the liquid volume （ml）/solid mass （g）, molar ratio of NaOH/SMCA and H2O/straw （ml：g） were 18：1, 4：3 and 1：2, respectively. Under the optimized reaction conditions, the yield of CMC in the products could reach 40.70%, the substitution degree （DS） of CMC obtained reached 0.91, which was similar to that prepared from straw α-cellulose, which possessed special characteristics of low viscosity. The CMC was characterized with FTIR and ^1H NMR. Meanwhile, the lignin part with great industrial potential could also be separated from the products. Compared with the current utilization carboxymethylcellulose industry, the new process was of high α-cellulose as raw material in the not only lower cost, but also more simplified, and made full use of straw components.