Cellulose nanocrystals from agricultural residues (Eichhornia crassipes): Extraction and characterization

• DOI: 10.1016/j.heliyon.2023.e16436
• Publication Date: 2023-05-25T16:56:05Z
• Authors: Mohamed H. Hemida; Hesham Moustafa; Sherif Mehanny; Mohamed Morsy; Alain Dufresne; Eid N. Abd EL Rahman; M.M. Ibrahim
• Keywords: H1-99; XPS analysis; Science (General); 600; Nile rose; 540; Social sciences (General); Q1-390; [CHIM]Chemical Sciences; Agricultural residues; Acid hydrolysis; [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering; Cellulose nanocrystals extraction; Cellulose nanocrystals extraction;Agricultural residues;XPS analysis;Transmission electron microscopy;Acid hydrolysis;Nile rose; Transmission electron microscopy; Research Article

Extraction of cellulose nanocrystals (CNCs) from agro-residues has received much attention, not only for their unique properties supporting a wide range of potential applications, but also their limited risk to global climate change. This research was conducted to assess Nile roses (Eichhornia crassipes) fibers as a natural biomass to extract CNCs through an acid hydrolysis approach. Nile roses fibers (NRFs) were initially subjected to alkaline (pulping) and bleaching pretreatments. Microcrystalline cellulose (MCC) was used as control in comparison to Nile rose based samples. All samples underwent acid hydrolysis process at a mild temperature (45 °C). The impact of extraction durations ranging from 5 to 30 min on the morphology structure and crystallinity index of the prepared CNCs was investigated. The prepared CNCs were subjected to various characterization techniques, namely: X-ray diffraction (XRD), FT-IR analysis, Transmission electron microscopy (TEM), and X-ray Photoelectron spectroscopy (XPS). The outcomes obtained by XRD showed that the crystallinity index increased as the duration of acid hydrolysis was prolonged up to 10 min, and then decreased, indicating optimal conditions for the dissolution of amorphous zones of cellulose before eroding the crystallized domains. These data were confirmed by FT-IR spectroscopy. However, a minor effect of hydrolysis duration on the degree of crystallinity was noticed for MCC based samples. TEM images illustrated that a spherical morphology of CNCs was formed as a result of 30 min acid hydrolysis, highlighting the optimal 20 min acid hydrolysis to obtain a fibrillar structure. The XPS study demonstrated that the main constituents of extracted CNCs were carbon and oxygen.