A novel enzymatic approach to nanocrystalline cellulose preparation (original) (raw)
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Preparation and Characterization of Nanocrystalline Cellulose by Acid Hydrolysis of Cotton Linter
Taiwan Journal of Forest Science
】 The purpose of this study was to use acid hydrolysis of cotton linter to generate nanocrystal-line cellulose (NCC). Based on a 2 4 factorial design, the effects of sulfuric acid concentration, tem-perature, hydrolysis time, and the solid/liquid ratio on the NCC yield were examined. NCC speci-mens obtained from different sulfuric acid concentrations were subjected to a battery of analyses, including dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-trans-form infrared spectroscopy (FTIR), 13 C solid-state nuclear magnetic resonance (13 CSNMR), and a thermal gravimetric analysis (TGA) to probe the particle size distribution, morphology, functional group shifts, position of the carbon, and thermal degradation properties of the ensuing NCC. The results indicated that the sulfuric acid concentration and solid/liquid ratio at higher levels, and tem-perature and reaction time at lower levels were significantly conducive to increases in NCC yields. The main e...
Materials
Integrating enzymatic treatment and acid hydrolysis potentially improves the economics of cellulose nanocrystal (CNC) production and demonstrates a sustainable cellulosic ethanol co-generation strategy. In this study, the effect of enzymatic treatment on filter paper and wood pulp fibers, and CNCs generated via subsequent acid hydrolysis were assessed. Characterization was performed using a pulp quality monitoring system, scanning and transmission electron microscopies, dynamic light scattering, X-ray diffraction, and thermogravimetric analysis. Enzymatic treatment partially reduced fiber length, but caused swelling, indicating simultaneous fragmentation and layer erosion. Preferential hydrolysis of less ordered cellulose by cellulases slightly improved the crystallinity index of filter paper fiber from 86% to 88%, though no change was observed for wood pulp fibre. All CNC colloids were stable with zeta potential values below −39 mV and hydrodynamic diameters ranging from 205 to 294...
Bioresources
Cellulose is the Earth's most abundant biopolymer. Exploiting its environmentally friendly attributes such as biodegradability, renewability, and high specific strength properties are limited by our inability to isolate them from the secondary cell wall in an economical manner. Intermolecular and intramolecular hydrogen bonding between the cellulose chains is the major force one needs to overcome in order to isolate the cellulose chain in its microfibrillar form. This paper describes how a hydrogen bond-specific enzyme disrupts the crystallinity of the cellulose, bringing about internal defibrillation within the cell wall. Bleached kraft softwood pulp was treated with a fungus (OS1) isolated from elm tree infected with Dutch elm disease. FT-IR spectral analysis indicated a significant reduction in the density of intermolecular and intramolecular hydrogen bonding within the fiber. X-ray spectrometry indicated a reduction in the crystallinity. The isolated nano-cellulose fibers also exhibited better mechanical strength compared to those isolated through conventional methods. The structural disorder created in the crystalline region in the plant cell wall by hydrogen bond-specific enzymes is a key step forward in the isolation of cellulose at its microfibrillar level.
Preparation and Characterization of Cellulose Nanocrystals Extracted from Egyptian and Upland Cotton
Journal of Environmental Sciences. Mansoura University, 2020
Nowadays, cellulose nanocrystals (CNC) play a major role in industrial processes due to their unique properties which, in turns, able to enhance the physical properties of bulk materials. The interstice properties of CNC are vary regarding to the source of the used cellulosic materials. The study aimed to characterize cellulose CNC extracted from two different genotypes of cotton slivers; Egyptian extra-long staple (G.88) and upland medium staple length (BF FK37). As per acid hydrolysis, CNC was extracted from different genotypes of cotton slivers by the use of H2SO4 60% (w/w) at 60 ℃ for 60 min. Then, the extracted CNC was characterized by making used of different tools e.g., transmission electron microscopy (TEM), Dynamic Light Scattering (DLS), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Thermo Gravimetric analysis (TGA). Results revealed that, CNC was, successfully, extracted by acid hydrolysis of cotton slivers. Notably, the size of the obtained CNC was varied as genotypes of cotton slivers varies, which attained as shown from TEM; the average dimensions (diameter × length) of 36.46 ± 7 nm × 355 ± 98.3 nm for extra-long staple, 37.2 ± 14 nm × 284 ± 83 nm for medium staple. This fact was further supported by DLS as the size of extra-long staple was 22. 45 d.n and 35.77 d.n for medium staple. In addition, XRD results demonstrated that, both genotypes excited cellulose type I (crystalline polymorph). However, CNC extracted from extra-long showed higher crystallinity index (80%) than observed from medium staple. Moreover, the thermal stability observed for CNC of extralong is significantly higher than obtained from medium. By varying of the source of CNC, the size of the obtained crystals was varied besides crystallinity index and their thermal stability properties. Therefore, the using of extra-long staple length cotton slivers led to reduce the crystal size with improving in both crystallinity and thermal properties.
The main goal of this article is to provide an overview of recent research in the area of cellulose nanomaterial production from different sources. Due to their abundance, renewability, high strength and stiffness, eco-friendliness and low weight, numerous studies have been reported on the isolation of cellulose nanomaterials from different cellulosic sources and their use in high-performance applications. This report covers an introduction to the definition of nanocellulose as well as the methods used for isolation of nanomaterials (including nanocrystals and nanofibers, CNCs and CNFs, respectively) from various sources.
Preparation and Characterization of Microcrystalline Cellulose (MCC)
BioResources, 2009
Cotton linters were hydrolyzed with different concentrations of HCl (2.5-15%) to prepare microcrystalline cellulose. Infrared spectroscopy and thermal analysis were used to follow the effect of hydrolysis on the molecular structure of the produced microcrystalline cellulose. The loss in weight and the degree of polymerization of the produced hydrolyzed cotton linters were determined. Scanning electron microscope images and x-ray diffraction were also studied for more information about the crystallinity, fiber length, particle size, and shape of the produced microcrystalline cellulose. Water retention value and water absorption were estimated for the hydrolyzed cotton linters to explain the effect of hydrolysis on the amorphous and crystalline part of the hydrolyzed cotton linters. The obtained results showed that the crystallinity index of the hydrolyzed cotton increased by increasing acid concentration and then began to decrease at 15% HCl. Kinetic energy (calculated from thermogravimetric curves) of the hydrolyzed cellulose was higher than that of the untreated cotton linters, and at high acid concentration this activation energy began to decrease.
Carbohydrate polymers, 2019
In this work, cellulase, low-concentration cold alkali and cellulase combined with cold alkali were used to pretreat unbleached bagasse pulp from which cellulose nanofibrils (CNFs), about 30 nm in diameter, were successfully prepared through ultrafine grinding and high-pressure homogenization. X-ray diffraction analysis showed that cellulase pretreatment increased the crystallinity of CNFs. After low-concentration cold alkali pretreatment, the crystallinity of CNFs significantly reduced and the crystal structure of the cellulose changed from type I to type II. Thermogravimetric analysis showed that CNFs prepared by cellulase combined with cold alkali treatment produced more regenerated cellulose and had lower thermal stability. The use of cellulase and low-concentration cold alkali pretreatments combined with ultrafine grinding and high-pressure homogenization is an environment-friendly method for preparing CNFs. The use of low-concentration cold alkali reduces the consumption of alkali and clean water.
Effect of the chemical treatments on the characteristics of natural cellulose
2014
In order to characterize the morphology and size distribution of the cellulose fibers, natural cellulose from kenaf bast fibers was extracted using two chemical treatments; (1) alkali-bleaching-ultrasonic treatment and (2) alkalibleaching-hydrolysis. Solutions of NaOH, H 2 O 2 and H 2 SO 4 were used for alkalization, bleaching and hydrolysis, respectively. The hydrolyzed fibers were centrifuged at a rotation speed of 10000 rpm for 10 min to separate the nanofibers from the microfibers. The separation was repeated in 7 steps by controlling pH of the solution in each step until neutrality was reached. Fourier transform infrared (FTIR) spectroscopy was performed on the fibers at the final step of each treatment: i.e. either ultrasonic treated-or hydrolyzed microfibers. Their FTIR spectra were compared with FTIR spectrum of a reference commercial α-cellulose. Changes in morphology and size distribution of the treated fibers were examined by scanning electron microscopy (SEM). FTIR spectra of ultrasonic treated-and hydrolyzed microfibers nearly coincided with the FTIR spectrum of commercial α-cellulose, suggesting successful extraction of cellulose. Ultrasonic treatment for 6 h resulted in a specific morphology in which cellulose nanofibers (≥100 nm) were distributed across the entire surface of cellulose microfibers (5 m). Constant magnetic stirring combined with acid hydrolysis resulted in an inhomogeneous size distribution of both cellulose rods (500 nm-3 m length, 100-200 nm diameter) and particles 100-200 nm in size. Changes in morphology of the cellulose fibers depended upon the stirring time; longer stirring time resulted in shorter fiber lengths.
Extraction and analysis of cellulose nanocrystals from cotton balls by acid hydrolysis
2023
Cellulose is one of the most widely used natural polymers developed in eco-friendly methods, which has been used in various industrial processes and products since ancient times. The sources of cellulose materials are plant and wood fibers. Cellulosic materials are converted into cellulose nanocrystals (CNCs) using mechanical or chemical methods. In this study, the CNCs were obtained from cotton balls by acid hydrolysis method using sulfuric acid. The sulfuric acid hydrolysis method was performed with 64% (w/w) sulfuric acid and combined using a liquor ratio of 1:20 with cotton balls while being subjected to vigorous stirring at 50 oC for 60 minutes. The cellulose nanocrystals were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy analysis and X-ray Diffraction (XRD) techniques. The extracted cellulose nanocrystals had needle-shaped particles with a 6.35 nm average diameter and a length of 108.8 nm on average. The functional groups of the extracted cellulose nanocrystals were shown to have been evaluated through analysis of the FTIR spectra. Therefore, it was confirmed that the cellulose nanocrystals were successfully extracted from cotton balls using sulfuric acid hydrolysis. The distinctive crystalline cellulose phase of artificial cellulose nanocrystals was recognized using the XRD spectrum. Keywords: Acid hydrolysis, Cellulose nanocrystals, Cellulosic materials, Cotton fibers, Sulfuric acid.
ACS Appl. Mater. Interfaces , 2014
This work describes the measurement and comparison of several important properties of native cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), such as crystallinity, morphology, aspect ratio, and surface chemistry. Measurement of the fundamental properties of seven different CNCs/CNFs, from raw material sources (bacterial, tunicate, and wood) using typical hydrolysis conditions (acid, enzymatic, mechanical, and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation), was accomplished using a variety of measurement methods. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and 13 C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy were used to conclude that CNCs, which are rodlike in appearance, have a higher crystallinity than CNFs, which are fibrillar in appearance. CNC aspect ratio distributions were measured and ranged from 148 ± 147 for tunicate-CNCs to 23 ± 12 for wood-CNCs. Hydrophobic interactions, measured using inverse gas chromatography (IGC), were found to be an important contribution to the total surface energy of both types of cellulose. In all cases, a trace amount of naturally occurring fluorescent compounds was observed after hydrolysis. Confocal and Raman microscopy were used to confirm that the fluorescent species were unique for each cellulose source, and demonstrated that such methods can be useful for monitoring purity during CNC/CNF processing. This study reveals the broad, tunable, multidimensional material space in which CNCs and CNFs exist.