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. 2022 Sep 15;23(18):10764.
doi: 10.3390/ijms231810764.

Preparation of Spherical Cellulose Nanocrystals from Microcrystalline Cellulose by Mixed Acid Hydrolysis with Different Pretreatment Routes

Peng Zhu  1 , Luyao Feng  1 , Zejun Ding  1 , Xuechun Bai  1
Affiliations

Preparation of Spherical Cellulose Nanocrystals from Microcrystalline Cellulose by Mixed Acid Hydrolysis with Different Pretreatment Routes

Peng Zhu et al. Int J Mol Sci. .

Abstract

Spherical cellulose nanocrystal (CNC), as a high value cellulose derivative, shows an excellent application potential in biomedicine, food packaging, energy storage, and many other fields due to its special structure. CNC is usually prepared by the mixed acid hydrolysis method from numerous cellulose raw materials. However, the pretreatment route in preparing spherical CNC from cellulose fiber is still used when choosing microcrystalline cellulose (MCC) as the raw material, which is not rigorous and economical. In this work, pretreatment effects on the properties of spherical CNC produced from MCC by mixed acid hydrolysis were systematically studied. Firstly, the necessity of the swelling process in pretreatment was examined. Secondly, the form effects of pretreated MCC (slurry or powder form) before acid hydrolysis in the preparation of spherical CNC were carefully investigated. The results show that the swelling process is not indispensable. Furthermore, the form of pretreated MCC also has a certain influence on the morphology, crystallinity, and thermal stability of spherical CNC. Thus, spherical CNC with different properties can be economically prepared from MCC by selecting different pretreatment routes through mixed acid hydrolysis.

Keywords: crystallinity; microcrystalline cellulose; mixed acid hydrolysis; pretreatment; spherical cellulose nanocrystals; thermal stability.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic process flow of (a) spherical cellulose nanocrystal (CNC) preparation from cellulose fiber, and (b) spherical CNC preparation from commercial microcrystalline cellulose (MCC).
Figure 2
Figure 2
(a) FTIR spectra of MCC, MCC after alkaline treatment, and MCC after alkaline treatment and swelling treatment; (b) FTIR spectra of CNC samples prepared through different pretreatment routes.
Figure 3
Figure 3
FE-SEM images of (a) MCC, (b) MCC after alkaline treatment, and (c) MCC after alkaline treatment and swelling treatment (1000× magnification).
Figure 4
Figure 4
FE-SEM images of CNC samples prepared through different pretreatment routes (200,000× magnification).
Figure 5
Figure 5
(a) XRD patterns of MCC, MCC after alkaline treatment and MCC after alkaline treatment and swelling treatment; (b) XRD patterns of CNC samples prepared through different pretreatment routes.
Figure 6
Figure 6
(a) TG and (b) DTG curves of MCC, MCC after alkaline treatment and MCC after alkaline treatment and swelling treatment; (c) TG and (d) DTG curves of CNC samples prepared through different pretreatment routes.
Figure 7
Figure 7
Pretreatment routes of MCC and its products after mixed acid hydrolysis (the common method in existing works is marked with red lines).
See this image and copyright information in PMC

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