Parametric optimization of the production of cellulose nanocrystals (CNCs) from South African corncobs via an empirical modelling approach

Abstract

In this study, cellulose nanocrystals (CNCs) were obtained from South African corncobs using an acid hydrolysis process. The delignification of corncobs was carried out by using alkali and bleaching pretreatment. Furthermore, the Box-Behnken Design (BBD) was used as a design of experiment (DOE) for statistical experimentations that will result in logical data to develop a model that explains the effect of variables on the response (CNCs yield). The effects (main and interactive) of the treatment variables (time, temperature, and acid concentration) were investigated via the response methodology approach and the obtained model was used in optimizing the CNCs yield. Surface morphology, surface chemistry, and the crystallinity of the synthesized CNC were checked using scanning electron microscopy (SEM), a Fourier Transform Infra-red spectroscopy (FTIR), and an X-ray diffraction (XRD) analysis, respectively. The SEM image of the raw corncobs revealed a smooth and compact surface morphology. Results also revealed that CNCs have higher crystallinity (79.11%) than South African waste corncobs (57.67%). An optimum yield of 80.53% CNCs was obtained at a temperature of 30.18 °C, 30.13 min reaction time, and 46 wt% sulfuric acid concentration. These optimized conditions have been validated to confirm the precision. Hence, the synthesized CNCs may be suitable as filler in membranes for different applications.

Isolation and Characterization of Spherical Cellulose Nanocrystals Extracted from the Higher Cellulose Yield of the Jenfokie Plant: Morphological, Structural, and Thermal Properties

“…This result is in line with the result noted [45,46]. Because of the van der Waals force, stacking nanocrystals may be the cause of the observed spherical shape morphology [47]. J-CNC exhibited the nanoscale size in their TEM images, which were prone to form agglomerates among CNCs attributed to hydrogen bonding because several hydroxyls are present, as shown in Figure 3e.…”

“…This result is in line with the result noted [ 45 , 46 ]. Because of the van der Waals force, stacking nanocrystals may be the cause of the observed spherical shape morphology [ 47 ]. J–CNC exhibited the nanoscale size in their TEM images, which were prone to form agglomerates among CNCs attributed to hydrogen bonding because several hydroxyls are present, as shown in Figure 3 e. Strong intermolecular hydrogen bonds between the particles and possible hydrophilic interactions between the chains may have contributed to the agglomeration, which was also observed by [ 36 , 48 , 49 , 50 ].…”

Biogeneration of Valuable Nanomaterials from Agro-Wastes: A Comprehensive Review

“…The image of TEM plays a crucial role in cellulose micro-fibril and nanocrystal morphological studies. TEM has traditionally been the method of choice for visualizing the morphology of individual or grouped CMCs [242]. Variation in transmitted and diffracted beam intensity due to microstructural changes on the electron route that alter diffraction conditions is the origin of image contrast.…”

“…It is critical to check whether a satisfactory dispersion of NPs has been obtained while characterizing TEM. morphology of individual or grouped CMCs [242]. Variation in transmitted and diffracted beam intensity due to microstructural changes on the electron route that alter diffraction conditions is the origin of image contrast.…”

Hairy Nanocellulose-Based Supramolecular Architectures for Sustained Drug Release

“…These nanomaterials retain the advantageous properties of cellulose, and the abundance of their surface hydroxyl groups facilitates their functionalization. The liquid crystal behavior and the biodegradability of CNCs have made them highly attractive materials for biomedical applications, for waste treatment, in biocomposites, and for food preservation. − The increased interest in these sustainable materials has led to vast progression in their large-scale production. − In order to resolve the low capacity of surface functionalization of CNCs, hairy nanocelluloses (HNCs) have been produced by periodate oxidation, which solubilize the amorphous regions and, at the same time, allow for the cleavage of cellulose chains in the amorphous regions, leaving the soluble amorphous regions attached to the nanorods on both ends. − The HNCs resulting from this cleavage have dialdehyde-modified cellulose chains protruding from both sides of the crystalline region. By oxidizing some of the aldehyde groups on the amorphous regions of HNCs, bifunctional HNCs (BHNCs) can be synthesized, containing both aldehyde and carboxylic groups, further increasing the functionalization capacity of these nanocelluloses. ,, These cellulose derivatives are optimal guest polymers for the threading of beta-cyclodextrin (βCD) supramolecular inclusion complexes, and combining βCD with celluloses has attracted great attention in recent years for developing advanced supramolecular materials with outstanding self-assembly and structural stability. , βCDs are cyclic oligosaccharides that consist of 7 glucopyranose units that form hydrophobic cavities and externally hydrophilic surfaces.…”