Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers

Abstract

A facile method is reported to prepare nanocellulose fibers from oil palm trunk fibers. The fibers were pretreated 2 hours with NaOH/urea solution, and the fully swelled fibers were mechanically treated through highpressure homogenization to obtain nanocellulose. The nanocellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR results revealed that there was no obvious difference between the spectra of the bleached fibers (BF), pretreated cellulose fibers (PCF), and cellulose nanofibers (NCF), which indicated that the pretreatment process is a non-derivative reaction. The crystallinity of PCF and NCF decreased and contained the cellulose I crystal structure. The PCF presented both a distorted structure and a coarser surface. The resulting NCF were approximately 10 nm to 100 nm in diameter with the length varying from hundreds of nanometers to several micrometers, as observed by SEM. The thermal degradation of NCF was 223 °C with about 20% weight loss, and the maximum degradation temperature was 338 °C. NaOH/urea showed potential as a mild solvent for preparing nanocellulose fibers.

Production of nanocellulose by enzymatic hydrolysis: Trends and challenges

“…These differences make the first procedure produces less toxic waste and less corrosive. This feature facilitates the application of nanocellulose via enzymatic hydrolysis in possible cosmetic and pharmaceutical products .…”

Extraction of thermally stable cellulose nanocrystals in short processing time from waste newspaper by conventional acid hydrolysis

“…This well-known specific property of CNC led to the application of nanocellulose-based membranes for CO 2 capture [32]. Figure 7 shows the XRD diffraction pattern of the CNC product with the diffraction peaks at 2θ=14.8°, 22.5°, and 34.32°, which were very close to the typical peaks of cellulose crystal structures reported in [11,13,27,28,33]. Sharp and narrow diffraction peak at 2θ=22.5°indicated high perfection of the crystal lattice.…”

“…The peaks at 1430 cm −1 which corresponded to -CH 2 bending vibration, a typical of the 'crystallinity band' in cellulose were also found [13]. The peaks in the 3333-3500 cm −1 and 1610-1639 cm −1 regions indicated the presence of O-H stretching vibration and O-H bending of the absorbed water, respectively.…”

“…In contrast, CNC isolation could also be performed by direct acid hydrolysis (60% (v/v) H 2 SO 4 solution at 45°C for 1.5 h) without the alkali and bleaching pretreatment. However, the first maximum degradation temperature of the CNC product was at 220°C [12], which was relatively lower than most reported temperature of about 300°C [8,[13][14][15]. It was highly probable that direct and longer process of acid hydrolysis could have degraded the thermal stability of the CNC product [16].…”

“…No peak was observed in the region of 1728-1731 cm −1 , which was reported as the characteristics of hemicellulose [23]. In addition, no peak was observed at 897 cm −1 , which is considered as the 'amorphous band' after acid hydrolysis [13].…”