羧乙基化和碱预处理玉米芯渣制备纳米纤维素的研究

Preparation of Nanocellulose from Corncob Residue Using Carboxyethylation and Alkali Pretreatment

关键词:  羧乙基化  碱预处理  玉米芯渣  纳米纤维素

Key Words:carboxyethylation  alkali pretreatment  corncob residue  nanocellulose

摘要:玉米芯提取木糖后剩余的残渣富含纤维素和木质素，采用羧乙基化反应和质量分数1%的NaOH溶液分别对玉米芯渣进行预处理，再经机械解离制备了纳米纤维素，最后经棒涂法制得纳米纤维素膜，并对预处理前后玉米芯渣、纳米纤维素及其膜的化学结构、组分含量、微观形貌、尺寸分布、水接触角和热稳定性进行了分析和表征。结果表明，羧乙基化预处理可增加玉米芯渣的羧基含量，同时脱除部分木质素，而碱预处理可脱除大部分木质素。经预处理后，玉米芯渣纤维尺寸明显降低、可及度增加。经机械解离后，羧乙基化预处理所得纳米纤维素的直径更小、分布更均匀，其经棒涂法所得膜也更加致密平滑，水接触角较大。另外，两种预处理方法均降低了所得纳米纤维素膜的热稳定性。

Abstract:The residue after extracting xylose from corncob is rich in cellulose and lignin. In this study， corncob residue was pretreated by carboxyethylation and 1% NaOH solution， respectively， and then fibrillated into nanocellulose using mechanical grinding. Finally， nanocellulose films were formed by rod coating method. The chemical structure， component content， micro morphology， size distribution， water contact angle and thermal stability of the corncob residue， nanocellulose and their films were analyzed and characterized. The results showed that carboxyethylation pretreatment could increase the content of carboxyl group in corncob residue and remove part of lignin， while alkali pretreatment could remove most of lignin. After pretreatment， the size of raw materials decreased significantly and the accessibility increased. Compared with alkali pretreatment， the diameter and distribution of nanocellulose obtained using carboxyethylation pretreatment were smaller and more uniform. At the same time， the surface of these films was compact and their water contact angle was large. In addition， both pretreatment methods reduced the thermal stability of the final nanocellulose films.