Individualization of microfibrillated celluloses from oil palm empty fruit bunch: comparative studies between acid hydrolysis and ammonium persulfate oxidation

Abstract

In the present study, the feasibility and the practicability of two different approaches to the individualization of microfibrillated celluloses (MFCs) from oil palm empty fruit bunches were evaluated. Some properties of MFCs prepared by ammonium persulfate (APS) oxidation were investigated and compared with those extracted using sulfuric acid hydrolysis. Fourier transform infrared observation demonstrated that almost all the hemicelluloses and lignin were effectively removed after the sulfuric acid hydrolysis, which was substantiated by the disappearance of the characteristic peaks of these two noncellulosic components at 1735 and 1508 cm−1, respectively. However, a peak at 1735 cm−1 was observed in the spectrum of APS-oxidized MFCs because the products prepared by this treatment are stabilized by carboxyl groups instead of sulfate half-ester groups, which introduced by sulfuric acid. Furthermore, X-ray diffractograms of MFCs revealed the decrease in crystallinity after sulfuric acid hydrolysis but remained similar after APS oxidation. Thermogravimetric analysis was employed to determine the thermal stability of the treated fibers. In addition, the morphologies and diameters of MFCs were determined by field-emission scanning electron microscopy. MFCs formed by these two different techniques exhibited long and network-like fibrils with widths ranging from 8 to 40 nm. UV-Vis spectroscopy was used to monitor the optical transmittance of the nanocellulose suspensions.

Microscopic Structural Features and Properties of Single Fibers from Different Morphological Parts of the Windmill Palm

“…As shown in Fig. 4, the typical X-ray diffractograms obtained for all of the powdered windmill palm raw materials and extracted fiber samples exhibited the typical semi-crystalline patterns with an amorphous broad hump and a crystalline peak (Goh et al 2016). All of the samples possessed diffraction peaks centered at approximately 16° (overlapping of the characteristic 101 and 10ȋ planes), 22° (correspond to 002 plane), and 34° (correspond to 040 plane), which are characteristics of cellulose-I (Ortunati et al 2013).…”

“…Celluloses are semicrystalline biopolymers known to possess both crystalline and amorphous domains in their molecular structure (Goh et al 2016). As shown in Fig.…”

“…The CrI for PF, LBF, FBF, and LSF fractions were 46%, 44%, 46%, and 49%, respectively. The increased crystallinity observed after the alkali treatment was related to the increased rigidity and stiffness properties of the cellulose structure, which led to a higher tensile strength and Young's modulus of the fibers (Haafiz et al 2013;Goh et al 2016).…”

“…After the alkali treatment, the crystallinity indices were anticipated to be higher than those for the raw materials because of the partial hemicelluloses and lignin removal, which were considered to have no contributions to the crystallinity (Goh et al 2016). However, cellulose has a portion of imperfect crystallites that also contribute to the amorphous content of the lignocellulosic biomass (Mendes et al 2015).…”

Xylose recovery from dilute-acid hydrolysis of oil palm (Elaeis guineensis) empty fruit bunches for xylitol production

“…In this study, a high concentration of xylose was produced in the hydrolysate of the OPEFB, with large particle sizes and a low concentration of glucose. A large particle size and dilute-acid hydrolysis were probably not able to reduce the crystallinity of the cellulose, and the glucose concentration in the medium was less than that with smaller sizes of fiber (Goh et al, 2016).…”