Isolation and Characterization of Nanocrystalline Cellulose from Ramie Fibers via Phosphoric Acid Hydrolysis

ABSTRACT

Nanocrystalline cellulose (NCC) was successfully isolated using cellulose extracted from ramie fibers via chemical pretreatments followed by phosphoric acid hydrolysis. The effects of acid concentrations and hydrolysis times on the characteristics of the NCC were investigated in this work. The obtained NCCs were characterized using Fourier infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Fourier transform-infrared spectroscopy confirmed that hemicellulose and lignin were removed during the chemical pretreatments and hydrolysis. The results showed that the crystallinity index increased with increasing an acid concentration up to 16 M and then decreased drastically. The optimal acid concentration was found to be 16 M phosphoric acid at 150°C for 90 min during hydrolysis resulting in a rod-shaped NCC with a high crystallinity (89.28%), the average diameter (21.4 nm), and the average length (215.4 nm). The thermal stability was found to decrease with increasing acid concentration. The characteristic of NCCs was affected significantly by the acid concentration but not the hydrolysis time.

摘要

以苎麻纤维中提取的纤维素为原料，经化学预处理和磷酸水解，成功地分离出纳米晶纤维素（NCC）. 研究了酸浓度和水解时间对纳米纤维素特性的影响. 利用傅立叶红外光谱（FT-IR）、X射线衍射（XRD）、透射电子显微镜（TEM）和热重分析（TGA）对所得纳米纤维素进行了表征. 傅立叶变换红外光谱证实，半纤维素和木质素在化学预处理和水解过程中被去除. 结果表明，结晶度指数随酸浓度的增加而增加，最高可达16m，然后急剧下降. 最佳酸浓度为16m磷酸在150℃下水解90min，得到结晶度高（89.28%）、平均直径（21.4nm）和平均长度（215.4nm）的棒状纳米晶纤维素. 热稳定性随酸浓度的增加而降低. 酸浓度对纳米纤维素的性质有显著影响，但水解时间对其影响不大.

KEYWORDS:

• Nanocrystalline cellulose
• ramie fibers
• phosphoric acid concentration
• hydrolysis time
• crystallinity index
• thermal stability

关键词:

• 纳米纤维素
• 苎麻纤维
• 磷酸浓度
• 水解时间
• 结晶度指数
• 热稳定性

Acknowledgments

The authors would like to thank Universitas Gadjah Mada, Yogyakarta, Indonesia for the financial support through the research grant of Hibah Penelitian Dasar Unggulan Perguruan Tinggi (PDUPT) (Contract no. 110/UN1/DITLIT/DIT-LIT/LIT/2018 and 2645/UN1.DITLIT/DIT-LIT/LT/2019).

Additional information

Funding

This work was supported by the Hibah Penelitian Dasar Unggulan Perguruan Tinggi [110/UN1/DITLIT/DIT-LIT/LIT/2018 and 2645/UN1.DITLIT/DIT-LIT/LT/2019], Kementerian Riset, Teknologi dan Pendidikan Tinggi, Indonesia.