Hydrolysis Of Microcrystalline Cellulose Research Articles

Hydrolyzed Forms of Cellulose and Its Metal Composites for Hydrogen Generation: An Experimental and Theoretical Investigation

The quest for a smooth transition from fossil fuels to clean and sustainable energy has warranted studies on alternative energy materials. Herein, we report on an experimental and theoretical study focused on hydrogen generation through the hydrolysis of microcrystalline cellulose (MCC) treated in different media (deionized water, sodium hydroxide) and MCC functionalized with magnesium (MCC-Mg), titanium (MCC-Ti), and niobium (MCC-Nb). The XRD results reveal the decreased crystallinity of MCC due to ball milling along with the formation of metal oxide composites between MCC and various metals (magnesium, titanium, and niobium). Theoretical studies using NVT molecular dynamic simulations with the NH chain thermostat implemented in the Dmol3 provides further support to the experimental results reported herein. The results from the experimental and theoretical studies revealed that ball milling and composite formation with metal species enhanced the kinetics of the hydrolysis of MCC and, consequently, hydrogen generation, while the addition of NaOH and urea inhibited the hydrogen yield.

Zeolite-assisted acid hydrolysis of cellulose: Optimization of reaction conditions and chemical pretreatments for enhancing HMF yields

This study explores the hydrolysis of microcrystalline cellulose under soft conditions using a combination of both homogeneous (HCl) and heterogeneous catalysts (β-zeolite). The impact of temperature and HCl concentration is studied, revealing that the most favorable results (highest HMF yield) are achieved at 140ºC with 0.02 %w/w of HCl (19% of selectivity, 23.5% of conversion). Nevertheless, the inherent recalcitrance of cellulose limits the conversion and the HMF concentration. Three chemical pretreatments (HCl, H2O2, HNO3) are considered, assessing the effect of concentration. Except when using 69% of HNO3, the bulk structure of cellulose remains largely unaffected (low effect on conversions). However, the surface of cellulose undergoes chemical alteration due to the acidic and predominantly oxidizing pretreatment, leading to the detection of C5 compounds. These modifications have a positive influence on the reaction, significantly enhancing the selectivity towards HMF up to 50% (34% of conversion).

Enzymatic hydrolysis of microcrystalline cellulose for efficient and economic production of astragalin in metabolic engineering of Escherichia coli

Cellulose is the most abundant biomass in nature, and the development of high-value utilization technologies for cellulose is of great significance. In this work, a recombinant strain was engineered by introducing Arabidopsis thaliana glycosyltransferase (AtUGT78D2) and the cellobiose phosphorolysis route to produce astragalin from kaempferol. By optimizing the transformation conditions, the production of astragalin increased from 1053 to 3031 mg/L with the addition of cellobiose. Subsequently, the cellulose enzymatic solution was used to replace cellobiose as the carbon source and UDP-glucose precursor for producing astragalin. By optimizing enzymatic conditions and adding additives, the concentration of cellobiose significantly increased, resulting in an increase in the production of astragalin to 2279 mg/L. The adsorption strategy was employed to modulate the composition and activity of cellulase, and the ratio of cellobiose to glucose in the cellulose enzymatic solution increased from 0.73 to 1.62, with the yield of cellobiose reaching up to 5.9 g/L. Finally, the highest production of astragalin in the recombinant strain reached 2654 mg/L when the optimal ratio of cellobiose to glucose was used as the carbon source. This study provides a novel method for producing astragalin by using the enzymatic hydrolysis of microcrystalline cellulose.

Effect of various aromatic compounds with different functional groups on enzymatic hydrolysis of microcrystalline cellulose and alkaline pretreated wheat straw

Low molecular aromatic compounds are detrimental to the enzymatic hydrolysis of lignocellulose. However, the specific role of their functional groups remains unclear. Here, a series of nine aromatic compounds as additives were tested to understand their effect on the hydrolysis yield of microcrystalline cellulose (MCC) and alkaline pretreated wheat straw. Based on the results, the inhibition of aldehyde groups on MCC was greater than that of carboxyl groups, whereas for the alkaline pretreated wheat straw case, the inhibitory effect of aldehyde groups was lower than that of carboxyl groups. Increased methoxyl groups of aromatic compounds reduced the inhibitory effect on enzymatic hydrolysis of both substrates. Stronger inhibition of aromatic compounds on MCC hydrolysis was detected in comparison with the alkaline pretreated wheat straw, indicating that the substrate lignin can offset the inhibition to a certain extent. Among all aromatic compounds, syringaldehyde with one aldehyde group and two methoxyl groups improved the glucan conversion of the alkaline pretreated wheat straw.

Impact of ionic liquid's cation alkyl chain length and reaction time on cellulose nanocrystals preparation

Traditional methods to obtain cellulose nanocrystals typically involve mechanical and chemical processes and develop an improved process in terms of efficiency, sustainability, and the quality of CNCs produced are interesting. In this sense, we aimed to prepare cellulose nanocrystals (CNCs) from the hydrolysis of microcrystalline cellulose using protic ionic liquids (PILs), named 3-diethylamino-propylammonium hexanoate ([DEAPA][Hex]), 3-dimethylamino- 1-propylammonium hexanoate ([DMAPA][Hex]), and propylammonium hexanoate ([PA][Hex]) at different reaction times. The PILs demonstrated efficiency in producing cellulose nanocrystals, regardless of the cation size and reaction times. However, as expected the properties of the CNCs varied depending on the studied condition. The highest yield was observed in DMAPA[Hex], with a 34 % conversion. Crystalline indices decreased independent of the cation sizes and reaction times. Thermal stabilities were shifted to higher temperatures up to 92 ºC probably due to PILs cation sizes. In contrast, increasing reaction times decreased nanocrystals’ thermal stabilities up to 51ºC. So, protic ionic liquids (PILs) can be considered more environmentally friendly or sustainable solvents compared to traditional organic solvents for preparing cellulose nanocrystals. In the present work, it is reported an alternative method for obtaining CNCs and additionally provide the best preparation conditions for achieving important properties of this nanomaterial, with the potential for various applications.

Design and properties of alginate/gelatin/cellulose nanocrystals interpenetrating polymer network composite hydrogels based on in situ cross-linking

Alginate (Alg) hydrogels have attracted extensive attention in the biomedical field due to their biocompatibility. However, single Alg hydrogels exhibit weak mechanical strength, poor stability and cell adhesion, which severely restricts their biomedical application. For this reason, we designed alginate/gelatin/cellulose nanocrystals (Alg/G/CNCs) composite hydrogels by combining interpenetrating network (IPN) technology, cellulose nanocrystals (CNCs) reinforcement and in situ cross-linking method to improve the functional defects of Alg hydrogels. The structure and properties of the resultant Alg/G/CNCs composite hydrogels were comprehensively evaluated by FT-IR, TGA, XRD, swelling and degradability measurements, and cytocompatibility experiments. Alg/G/CNCs composite hydrogels with regular three-dimensional porous network (3D) structures was successfully fabricated through the ionic cross-linking of alginate and the covalent cross-linking of gelatin, followed by the reinforcement of colloidal cellulose nanocrystals (CNCs) that were prepared by sulfuric acid hydrolysis of microcrystalline cellulose (MCC). The addition of CNCs could generate interaction force with the polymer in the IPN matrix, which was able to regulate the physicochemical properties of the composite hydrogel to a certain extent. Moreover, with the increase of gelatin (G) content, the compressive strength of Alg/G/CNCs composite hydrogels gradually increased, while the swelling property decreased gradually. Meanwhile, Alg/G/CNCs composite hydrogels exhibited good cell adhesion, proliferation and differentiation properties. In particular, Alg/0.5G/CNCs composite hydrogels displayed the best cell proliferation effect, while Alg/2G/CNCs composite hydrogels revealedthe most significant cell differentiation effect. Therefore, Alg/G/CNCs composite hydrogels could exhibit good mechanical properties and biocompatibility, which possessed great application potential in the field of tissue engineering.

Magnetic solid acid catalyst derived from different alkaline pretreatment of rice straw for hydrolysis of microcrystalline cellulose

Magnetic solid acid catalyst derived from different alkaline pretreatment of rice straw for hydrolysis of microcrystalline cellulose

The sulfonated natural silica-based catalyst prepared from rice straw for hydrolysis of microcrystalline cellulose

The sulfonated natural silica-based catalyst prepared from rice straw for hydrolysis of microcrystalline cellulose

Synthesis and characterisation of sulfated-nanocrystalline cellulose in epoxy coatings for corrosion protection of mild steel from sodium chloride solution

Biomaterials such as nanocrystalline cellulose (NCC) have attracted considerable attention in coating production industries due to their sustainable and renewable attributes. This work presents NCC obtained from the hydrolysis of microcrystalline cellulose and sulfation treatment of NCC to obtain sulfated-NCC (S-NCC) using a chemical agent for corrosion protection of mild steel in 3.5 wt.% NaCl solution. Two types of anticorrosion coatings were formulated by incorporating either NCC or S-NCC of different loading ratios (10 wt.% to 50 wt.%) to epoxy-matrix to form composite coatings. The structural characterisations of NCC and S-NCC showed that the sulfation introduced sulfate ester groups on NCC. The morphological characterisations displayed that the average particle sizes obtained for both ranged between 40 nm and 50 nm. Electrochemical measurements were conducted to obtain the anticorrosion behaviour of the composite coatings in the corrosive solution. The results indicated that the sulfation of NCC improved the anticorrosion performance to 99.7%, and the best performance was obtained from a coating containing 20 wt.% S-NCC. Finally, a mechanism for corrosion protection of S-NCC coating was proposed where electrostatic repulsion of chloride species from the coated mild steel occurred. This study, therefore, demonstrates the applicability and importance of S-NCC in improving the anticorrosion performance of epoxy coatings for maritime applications.

Chiral Nematic Solvent-Responsive Actuator Based on a Cellulose Nanocrystal Template

Photonic actuators have attracted much attention because their periodic photonic crystal structures can produce dual responses of color and motion under stimulus responses. However, photonic actuators face some problems in their manufacture, such as their fragility, high cost, and narrow tunable optical range. It is challenging to use low-cost and simple methods to fabricate a flexible, wide-range response and multicolor photonic actuators. Two cellulose nanocrystals (CNCs) are made by sulfuric acid hydrolysis of microcrystalline cellulose or pulp, which emerged blue and red following evaporative assembly, respectively, and their compositions are adjusted to modify the optical color of the final photonic thin films. The introduction of graphene oxide (GO) and the sacrifice of the CNC template result in a mesoporous structure that provides a conduit for polar liquids. When the film absorbs water, the film expands to increase the layer spacing of the film. Due to the asymmetric structure of the film, the film has different expansion rates, which makes a red shift in the color and directional bending. The film changes color from green to red in 25 s when immersed in water and 20 min in dimethyl sulfoxide (DMSO), but no color change occurs in other solutions with less polarity even after 3 months of soaking. Furthermore, the reaction rate of the film in DMSO depends on the temperature. The film changes color from blue to red in DMSO at 30 °C in 10 min but just 3 min at 70 °C, demonstrating that increasing the temperature speeds up the passage of polar solvent molecules and increases the response rate of the film. The application prospects for the prepared nanocomposite films with changing structural colors and solvent-responsive drivability are favorable in optical actuators, solvent viewers, and other applications.

Environmental Impact Assessment of Chitin Nanofibril and Nanocrystal Isolation from Fungi, Shrimp Shells, and Crab Shells

Chitin nanoparticles are responsible for the outstanding mechanical properties found in the exoskeletons of crustaceans and are finding applications in many scientific and technological fields. Following a Circular Economy approach, diverse biomass wastes can be valorized to be reintroduced back into the economic cycle while preventing biowaste landfill upon isolation of chitin nanoparticles. Novel environmentally sustainable paths over the conventional chitin nanoparticle extraction involving harsh acid-hydrolysis treatments from crustacean shells have been recently proposed. In particular, fungi emerge as an attractive alternative provided the demineralization process with acids such as HCl is circumvented. In spite of this recognized virtue, no works have quantified the environmental impacts of these processes. The life-cycle assessment methodology is applied to close this gap and quantify the cradle-to-gate impacts of chitin nanofibril extraction from fungi. The results are compared to conventional chitin nanocrystal hydrolytic isolation processes from shrimp shells, chitin powder, and crab shells, together with sulfuric-acid-induced hydrolysis of microcrystalline cellulose to cellulose nanocrystals. Eighteen impact indicators are analyzed scaling-up laboratory quantities into processes treating 1 kg of biowastes. A global warming potential value of 18.5 kg·CO2-equiv per 1 kg of chitin nanofibrils is obtained, well below the 906.8, 105.2, 543.5, and 177.9 kg CO2-equiv·kg–1 values obtained for chitin nanocrystals from shrimp shells, chitin powder, crab shells, and cellulose nanocrystals, respectively. A sensitivity analysis shows a 10.1–62.6% impact decrease to a minimum value of 14.7 kg CO2-equiv·kg–1 for chitin nanofibril isolation from fungi considering 95% recirculation of the solvent/NaOH, highlighting the environmentally sustainable character of chitin nanofibril extraction from fungi. The potential application of chitin nanoparticles into environmentally sustainable materials and devices is explored. These results provide novel cues for the environmentally friendly synthesis of nanochitin, guiding the implementation of sustainable approaches in the field of biomass nanoparticles.

Multifunctional Enzyme with Endoglucanase and Alginase/Glucuronan Lyase Activities from Bacterium Cellulophaga lytica.

Cellulophaga lytica is a Gram-negative aerobic bacterium in the genome of which there are many genes encoding polysaccharide degrading enzymes. One of the enzymes named ClGP contains a glycoside hydrolase domain from the GH5 family and a polysaccharide lyase domain from the PL31 family. The enzyme also contains the TAT signaling peptide and the TIGR04183 domain that indicates extracellular nature of the enzyme. Phylogenetic analysis has shown that the enzymes most closely related to ClGP and containing all four domains (TAT, GH5, PL31, TIGR04183) are widespread among bacterial species belonging to the Flavobacteriaceae family. ClGP produced by the recombinant strain of E. coli was purified and characterized. ClGP exhibited activity of endoglucanase (EC 3.2.1.4) and catalyzed hydrolysis of β-D-glucan, carboxymethyl cellulose sodium salt (CMC-Na), and amorphous cellulose, but failed to hydrolyze microcrystalline cellulose and xylan. Products of CMC hydrolysis were cellobiose and cellotriose, whereas β-D-glucan was hydrolyzed to glucose, cellobiose, cellotetraose, and cellopentaose. ClGP was more active against the poly-β-D-mannuronate blocks than against the poly-α-L-glucuronate blocks of alginic acid. This indicates that the enzyme is a polyM lyase (EC 4.2.2.3). ClGP was active against polyglucuronic acid, so it displayed a glucuronan lyase (EC 4.2.2.14) activity. The enzyme had a neutral pH-optimum, was stable in the pH range 6.0-8.0, and displayed moderate thermal stability. ClGP effectively saccharified two species of brown algae, Saccharina latissima and Laminaria digitata, that suggests its potential for use in the production of biofuel from macroalgae.

Hierarchical model screening on enzymatic hydrolysis of microcrystalline cellulose

Hierarchical model screening on enzymatic hydrolysis of microcrystalline cellulose

Shifting to Transparent/Hazy Properties: The Case of Alginate/Network Cellulose All-Polysaccharide Composite Films.

Light-management films made entirely from natural polymers with tunable haze properties are developed via a facile approach. A novel green method based simply on the blending of network cellulose (NC)/water suspension with alginate (CaAlg) aqueous solution is proposed. The unique NC suspension created by a controlled hydrolysis of microcrystalline cellulose acts as the scatterer media while alginate serves as the transparent host matrix. NC features isotropic intertwined network of nanofibers that contributes to light scattering and produces optical haze. The opaque but hazy NC is dispersed purposefully in the alginate film, where its original properties are preserved owing to its poor solubility in water. Additionally, the dispersion notably increases the roughness of the composite film surface and acts as a light scatterer. Eventually, composite CaAlg/NC film with high transparency (>94%) and customized haze (15-73%) at 550 cm-1 wavelength is fabricated. Herein, the transparent alginate is successfully combined with the hazy cellulose of uniformly distributed nanofibers by blending to fabricate transparent/hazy all-natural films. The fabricated films exhibit high transparency with tailored transmission haze. The film is highly fitting for large-scale production and adequate to meet different haze requirements to accommodate different applications such as privacy protection films and antiglare/antireflection coatings.

Hydrothermal hydrolysis of microcrystalline cellulose from birch wood catalyzed by Al2O3-B2O3 mixed oxides

Hydrothermal hydrolysis of microcrystalline cellulose from birch wood catalyzed by Al2O3-B2O3 mixed oxides

Comparative study between mechanical and chemical treatments for the preparation of nanocellulose

Nanocrystalline cellulose (NCC) is usually obtained by the acid hydrolysis of microcrystalline cellulose for its use as polymer reinforcement. An ecological alternative to this process, avoiding the use of acids, is a mechanical method. High intensity ultrasonication (HIU) in optimal conditions (time, wave amplitude, volume ratio fiber/solution, cellulose extraction source) can be applied to prepare nanofibrillated cellulose (NFC). In this work, the HIU method was used to mechanically prepare NFC. Ultrasonication time (t) and wave amplitude (A) were optimized seeking for NFC with high crystallinity, strong thermal stability, large aspect ratio (length to diameter) and large surface to volume ratio with diameter in nanometer scale. The morphology and the physical/chemical properties of the NFC prepared at optimal HIU conditions were compared with those of NCC prepared from the same cellulose source at optimal acid hydrolysis (AH) conditions. Similar purity, lower crystallinity, improved thermal stability and larger aspect ratio with diameter in nanoscale were obtained for NFC prepared by HIU. These results can be used as an initial screening for the selection of the optimal process for NCC manufacture focusing on their use as polymer reinforcement.

Preparation and separation of pure spherical cellulose nanocrystals from microcrystalline cellulose by complex enzymatic hydrolysis

Spherical cellulose nanocrystals (CNCs), as a new and high value cellulose derivative, shows excellent application potential in many fields due to its special structure. The accurate and effective separation of pure spherical CNCs lays foundation for its further application. In this work, spherical CNCs were prepared by enzymatic hydrolysis of microcrystalline cellulose (MCC) with complex enzymes. In order to determine the optimal separation conditions of pure spherical CNCs, turbidity and Zeta potential were used to analyze the influence of pH on system stability, and the size and morphology of samples were characterized by DLS, AFM and SEM. The results showed that spherical CNCs with particle size of 24–76 nm can be separated from large particles with the help of alkali (pH = 9) dispersion and centrifugation speed of 3000 rpm. After three acid (pH = 4) washes, pure spherical CNCs were extracted and reducing sugars and enzyme proteins were removed. Compared with MCC, spherical CNCs had lower crystallinity but stronger reactivity and higher heat transfer. DTG results showed that the maximum weight loss temperature of spherical CNCs prepared by enzymatic hydrolysis was 309 °C.

Cellulose I nanocrystals (CNCs I) prepared in mildly acidic lithium bromide trihydrate (MALBTH) and their application for stabilizing Pickering emulsions

This study proposed a sustainable method to prepare cellulose I nanocrystals (CNCs I) from microcrystalline cellulose (MCC) in a mildly acidic lithium bromide trihydrate (MALBTH) system, a concentrated (50 wt%) solution of LiBr in water with recyclable formic acid (FA). First, the MCC was treated in the MALBTH system to generate CNCs with a uniform size, yield higher than 68.49% and crystallinity of 84.02%. Then, the CNCs could application for stabilizing Pickering emulsions for at least 15 days. Furthermore, FA was easily recycled from the MALBTH system, and the yield of the CNCs produced from the hydrolysis of MCC by using the recycled FA was still higher than 60%. Finally, this study provided a sustainable and green production of CNCs. A low-cost and environmentally friendly pathway to recover FA from the MALLBTH system at a high yield was still realized.

Proton Conductive, Low Methanol Crossover Cellulose-Based Membranes.

This work describes the development of sulfated cellulose (SC) polymer and explores its potential as an electrolyte-membrane for direct methanol fuel cells (DMFC). The fabrication of our membranes was initiated by the preparation of the novel sulfated cellulose solution via controlled acid hydrolysis of microcrystalline cellulose (MCC). Ion-conductive crosslinked SC membranes were prepared following a chemical crosslinking reaction. SC solution was chemically crosslinked with glutaraldehyde (GA) and cured at 30 °C to produce the aforementioned membranes. Effects of GA concentration on methanol permeability, proton conductivity, water uptake and thermal stabilities were investigated. The crosslinking reaction is confirmed by FTIR technique where a bond between the primary OH groups of cellulose and the GA aldehyde groups was achieved, leading to the increased hydrophobic backbone domains in the membrane. The results show that the time of crosslinking reaction highly affects the proton conduction and methanol permeability. The proton conductivity and methanol crossover (3M) of our GA crosslinked SC membranes are 3.7 × 10−2 mS cm−1 and 8.2 × 10−9 cm2 s−1, respectively. Crosslinked sulfated cellulose films have lower ion conductivity than the state-of-the-art Nafion (10.2 mS cm−1); however, the methanol crossover is three orders of magnitude lower than Nafion membranes (1.0 × 10−5 cm2 s−1 at 1 M). Such biofilms with high methanol resistivity address the major hurdle that prevents the widespread applications of direct alcohol fuel cells.

Introducing hydroxyl groups as cellulose-binding sites into polymeric solid acids to improve their catalytic performance in hydrolyzing cellulose

Effective hydrolysis of cellulose to glucose is a crucial step to produce fuels and chemicals from lignocellulosic biomass. Solid acids are promising alternatives of cellulases and homogenous acids for hydrolyzing cellulose. In this study, porous polymeric solid acids bearing hydroxyl and sulfonic acid groups were fabricated for cellulose hydrolysis in water through the low-cost Friedel-Crafts “knitting” polymerization of hydroxyl-containing aromatic monomers followed by sulfonation. The synthesized bifunctional solid acids could effectively hydrolyze microcrystalline cellulose (Avicel) to glucose by as high as 93 % at 120 °C within 48 h and ball-milled Avicel by 98 % at 120 °C in 24 h. The evidence from this study indicated that the outstanding catalytic performance of the solid acids was attributed to the porous structure (large surface area) and the presence of the hydroxyl (cellulose-binding group) in the solid acids.