Removal Of Hemicellulose Research Articles

Chemical functional groups of extractives, cellulose and lignin extracted from native Leucaena leucocephala bark

Bark from trees is considered a worthless raw material. However, this resource could be economically beneficial if utilized efficiently due to its rich chemical compounds. In this study, an ethanol toluene-soluble extractive, alpha-cellulose and lignin obtained from Leucaena leucocephala bark were characterized to determine their chemical functional groups. Based on FTIR spectral analysis, the results indicated that the bands of the functional groups of the extractive from the original bark remain unchanged; however, the absorbance intensity was found to be weaker in the group frequency and fingerprint regions. Removal of extractive, pectin, hemicellulose and lignin from the bark indirectly increased the strong absorbance intensity of cellulose. Broad peaks of OH stretching found in all spectra were assigned to the presence of phenolic OH and aliphatic structures for extractive and aromatic structures of lignin. It was revealed that aromatic functional groups were mainly found in the extractive, while water, carbonyl and ether were the dominant groups in cellulose, and methyl, methylene, carbonyl and carboxyl groups were enriched in lignin.Graphic abstract

Synergism of sweeping frequency ultrasound and deep eutectic solvents pretreatment for fractionation of sugarcane bagasse and enhancing enzymatic hydrolysis

Sugarcane bagasse (SCB) is an abundant agricultural waste in China and the conversion of the waste into plethora of useful resources is very vital. To achieve this, fractionation of the waste is highly important in the biomass biorefinery. The present study aims at investigating the synergistic role of deep eutectic solvents (DES) with sweeping frequency ultrasound (SFUS) and fixed frequency ultrasound (FFUS) in the fractionation of SCB to enhance the enzymatic saccharification process. Therefore, the effects of ultrasound (US) and DES conditions on the pretreatment efficiency were investigated. Under optimum SCB pretreatment conditions, FFUS (40 kHz, 60 min) + DES (choline chloride (ChCl)-lactic acid (LA), 120 °C, 3 h) and SFUS (40 kHz, 60 min) + DES (ChCl-LA, 120 °C, 3 h), the lignin removal rates were 80.13 and 85.62%, respectively. The hemicellulose removal rates were 78.08 and 90.46%, respectively; and the contents of glucose, xylose and arabinose in the liquid fractions after FFUS + DES pretreatment were 7.07, 17.95 and 3.01%, respectively. However, the yield of glucose, xylose, and cellobiose after enzymatic hydrolysis of the SFUS + DES pretreated SCB were 86.76, 38.68, and 20.76%. Analytical studies revealed that the SFUS + DES pretreatment can effectively destroy the ultrastructure of SCB and reduce the crystallinity of cellulose. Furthermore, the mechanism of pretreatment with SFUS + DES was proposed, which confirmed the excellent performance of SFUS + DES. Thus, the application of SFUS + DES pretreatment was able to improve the removal of lignin and hemicellulose from SCBs.

Removal of Cadmium and Chromium by Mixture of Silver Nanoparticles and Nano-Fibrillated Cellulose Isolated from Waste Peels of Citrus Sinensis.

Nano-fibrillated cellulose (NFC) was extracted by a chemical method involving alkali and acid hydrolysis. The characterisation of the citrus sinensis fruit peel bran and nano-fibrillated cellulose was performed by XRD, FTIR, TEM, and FESEM. XRD confirmed the phase of NFC which showed monoclinic crystal with spherical to rod shape morphology with a size of 44–50 nm. The crystallinity index of treated NFC increased from 39% to 75%. FTIR showed the removal of lignin and hemicellulose from waste peels due to the alkaline treatment. Silver nanoparticles were also synthesised by utilizing extract of citrus sinensis skins as a reducing agent. Pharmaceutical effluent samples from an industrial area were tested by Atomic Absorption Spectrometry. Out of the four metals obtained, cadmium and chromium were remediated by silver nanoparticles with nano-fibrillated cellulose via simulated method in 100 mg/L metal-salt concentrations over a time period of 160 min. The highest removal efficiency was found for cadmium, i.e., 83%, by using silver and NFC together as adsorbents. The second highest was for chromium, i.e., 47%, but by using only NFC. The Langmuir and Freundlich isotherms were well fitted for the sorption of Cd (II) and Cr (II) with suitable high R2 values during kinetic simulation. Thus, the isolation of NFC and synthesis of silver nanoparticles proved efficient for heavy metal sorption by the reuse of waste skins.

Highly fluorescent graphene quantum dots from biorefinery waste for tri-channel sensitive detection of Fe3+ ions

Renewable lignocellulosic biomass can be effectively transformed to value-added products, enabling fast growth of related downstream processing. However, valorization of the by-produced cellulose-poor fraction, which is also in large volumes, is only occasionally reported regarding existing technologies. Here, a simple, general, and effective strategy for fabricating graphene quantum dots (GQDs) from the Miscanthus (MC) biorefinery waste consisting of sugars and depolymerized lignin, is developed. This process involves the fast and selective removal of most lignin and hemicellulose based on mild acid hydrotrope fractionation, with followed hydrothermal carbonization. The as-fabricated MC-derived GQDs (M-GQDs) exhibit several advantages such as few-layer graphene-like single crystalline structure, sulfur and nitrogen co-doping, bright fluorescence, excitation-dependent photoluminescence, and long fluorescence lifetime (11.95 ns). Furthermore, M-GQDs present prominent fluorescence reduction in the presence of Fe3+ with good linearity (≤0.995) and very low detection limit (≥1.41 nM). Later, it is found that the observed high sensitivity for Fe3+ is based on a dynamic quenching mechanism, which is caused by the Fe3+-induced increase in both the energy dissipation and photogenerated electron consumption. This work is anticipated to open new opportunities for promoting the integral valorization of biomass and sensitive fluorometric detection of Fe3+.

Cassava stem cellulose (CSC)Nanocrystal for optimal methylene BlueBio sorption with response surface design

The removal of cationic methylene blue (MB) dye from aqueous solution was studied using cellulose nanocrystal (CNC) from cassava stem cellulose extracted via acid hydrolysis. The cellulose nanocrystal was converted to 2, 2, 6, 6- tetramethylpiperidine-1-oxyl(TEMPO) CNC. CNC yield from cassava stem was 72%. FTIR showed absorption patterns typical of cellulose and CNC. It also proved the removal of lignin and hemicellulose in CNC. SEM and TEM analysis revealed that CNC has spherical particles. X-ray analysis showed that extracted CNC was crystalline in nature with crystallinity index of 83.24%. The adsorption behaviour of the CNC bio-adsorbent in aqueous solution revealed the effects of some process variables such as pH, temperature, ionic strength, initial dye concentration and contact time on the adsorption capacity of the CNC. Best dye adsorption of 93.3% was recorded at pH 2, MB concentration of 200 ​mg and 25mins via one factor at a time. High adsorption capacity of 823 ​mg/g was obtained. The adsorption of methylene blue was best described by Freundlinch model which indicates that the adsorption is on multiple heterogeneous surfaces and multiple adsorption layers provided by modified macro porous CNC. Optimal dye removal of 76% was obtained at 0.4 ​mg of CNC, 14mins and pH of 2 via RSM. Therefore CNC from cassava stem can be used in particles removal from contaminated water.

Development of non-derivatizing hydrate salt pre-treatment solvent for pre-treatment and fractionation of corn cob

Major concern in beneficiating lignocellulose is overcoming biomass recalcitrance through pre-treatment. Molten hydrate salts (MHS) is a green solvent with ability to swell and dissolve cellulose and biomass in a non-derivatizing way. Over the last decade, MHSs have been used for isolated cellulose dissolution, however very few studies have been reported on their effectiveness in pre-treating lignocellulosic biomass. Therefore, effectiveness of their application as solvent for pre-treating and fractionating corn cob is presented in this article. In this study, seven molten hydrate salt pre-treatment solvent systems such as unary, binary and ternary mixtures of ZnCl2.4H2O, LiClO4.3H2O and Urea were investigated for their ability to pre-treat and fractionate biomass. The pre-treatment experiments were carried out in a shaking incubator at 70°C for 60 minutes at a biomass: solvent ratio of 1:10. The surface chemistry of the biomass was checked before and after pre-treatment using Fourier Transform infrared spectroscopy. X-ray diffraction and scanning electron microscopy were employed to check the crystallinity and surface morphology of the biomass. Physicochemical analysis consistently indicated a disruption in the structure of corncob due to removal of lignin and hemicellulose during the pre-treatment process. Additionally, results showed a decrease in crystallinity and a change in surface morphology after the pre-treatment using all the seven solvent systems (MHS solvents). The use of ZnCl2.4H2O/ Urea solvent displayed 100% recovery of cellulose, 42% recovery of hemicellulose and 44% recovery of lignin from the corn-cob when compared to the performance of the other proposed solvent systems in this study.

Effect of Surface Modification on Mechanical Properties of Buri Palm (Corypha Utan) Fibre Composite Reinforcement

Natural fibre materials are replacing synthetic fibre materials since they are considered as a low-cost, lightweight, and biodegradability engineering materials with a good specific strength. However, the effects of some process and geometrical parameters (such as fibre type, size, and concentration, and chemical modification) on the strength of the final natural composite product are not well documented. The purpose of the research is to analyse the physical and mechanical properties of single-strand buri palm fibre under different conditions and surface modification. The buri palm fibre was treated using 5 wt.% and 10 wt.% sodium hydroxide (NaOH) with a duration of 1 and 24 h immersion throughout the whole process. For a single-strand test, the samples were carefully extracted from the corresponding woven fibre by hand. While the woven buri palm fibre composite was fabricated by employing 4 and 5-layering sequences in the hand lay-up technique followed by the compression method. The buri palm fibre showed that a higher concentration of NaOH solution and immersion period led to a lower density. The effectiveness of the alkali treatment in the removal of cellulose and hemicellulose from the fibre strands was verified by chemical composition in FTIR investigation. The highest tensile strength of 159.16 MPa was indicated from the result of single-strand treated with 5 wt.% NaOH for 24 h immersion. This treatment was found as the most appropriate treatment and is employed to fabricate both 4-layer and 5-layer stacking sequence composite. The 5-layer treated composite gives the highest tensile strength and flexural strength of 33.51 MPa and 56.72 MPa, respectively. In conclusion, the mechanical properties increased with the addition of each sequence layering treated fibres in the composite. The obtained results indicate that the utilisation of buri palm fibre as a reinforcement in the epoxy composite can be used in the lightweight and moderate load applications, such as the interior parts in the automotive industry.

High-Performance Bamboo Steel Derived from Natural Bamboo.

It is highly desirable to develop green and renewable structural materials from biomaterials to replace synthetic materials involved from civil engineering to aerospace industries. Herein, we put forward a facile but effective top-down strategy to convert natural bamboo into bamboo steel. The fabrication process of bamboo steel involves the removal of lignin and hemicellulose, freeze-drying followed by epoxy infiltration, and densification combined with in situ solidification. The prepared bamboo steel is a super-strong composite material with a high specific tensile strength (302 MPa g-1 cm3), which is higher than that (227 MPa g-1 cm3) of conventional high specific strength steel. The bamboo steel demonstrates a high tensile strength of 407.6 MPa, a record flexural strength of 513.8 MPa, and a high toughness of 14.08 MJ/m3, which is improved by 360, 290, and 380% over those of natural bamboo, respectively. Particularly, the mechanical properties of the bamboo steel are the highest among the biofiber-reinforced polymer composites reported previously. The well-preserved bamboo scaffolds assure the integrity of bamboo fibers, while the densification under high pressure results in a high-fiber volume fraction with an improved hydrogen bonding among the adjacent bamboo fibers, and the epoxy resin impregnated enhances the stress transfer because of its chemical crosslinking with cellulose molecules. These endow the bamboo steel with superior mechanical performance. Furthermore, the bamboo steel demonstrates an excellent thermal insulating capability with a low thermal conductivity (about 0.29 W/mK). In addition, the bamboo steel shows a low coefficient of thermal expansion (about 6.3 × 10-6 K-1) and a very high-dimensional stability to moisture attack. The strategy of fabricating high-performance bamboo steel with green and abundant natural bamboo as raw materials is highly attractive for the sustainable development of structural engineering materials.

Pretreatment is an important method for increasing the conversion efficiency of rice straw by black soldier fly larvae based on the function of gut microorganisms

Rice straw is considered as a renewable biomass energy source and its efficient utilization is still a topic worthy of attention. Black soldier fly larvae, Hermetia illucens (L.), (Diptera: Stratiomydiae) is a kind of saprophytic insect, which can effectively digest organic wastes. Here we report that alkaline peroxide-pretreatment improves the digestion of rice straw by these larvae, especially the decomposition of cellulose, which was at 70.9% compared to 58.2% without pretreatment. After conversion, the effective conversion rates of rice straw to larvae were 10.7% and 11.4%, for raw rice straw and rice straw with pretreatment, respectively. With pretreatment the composition of larval gut microorganisms was altered where Actinomyces, Dysgonomonas, Devosia and Pelagibacterium were the dominant flora for digesting rice straw. In addition, metabolism, environmental information processing and genetic information processing were the major gut microbial functions. These findings demonstrate that chemical pretreatment for the removal of lignin and hemicellulose was an effective measure for the digestion and consumption of rice straw by black soldier fly larvae.

The physiochemical alteration of flax fibers structuring components after different scouring and bleaching treatments

Scouring and bleaching are essential steps in flax yarn production; however, in many cases, these treatments have relatively low selectivity on non-cellulosic polysaccharides (NCPs) and lignin. Herein, the specific chemical properties of flax fibers through a variety of scouring and/or bleaching procedures are reviewed to understand their correlations with the mechanical and morphological characteristics. The hydrolysis behaviors of hemicellulose and lignin are different from those of cellulose during chlorine-alkali-oxygen (Cl-AO), enzyme-alkali-oxygen (EAO), and alkali-oxygen (AO) treatments, while the structural hemicellulose polysaccharides fractions were not affected by acid pretreatment followed by alkali scouring (AA) treatment. It was found that the unbleached AA treatment improved scouring efficiency to the greatest extent by decreasing 73.3 % of hemicellulose content and 59.8 % of lignin content compared to the untreated flax fibers and obtained the highest tensile strength (6.58 cN/dtex) and elongation (3.73 %). Delignification was more crucial on fiber tenacity and fineness than hemicellulose removal (R2 = 0.71, 0.79 vs R2 = 0.46, 0.61). Within the hemicellulose fractions, a corresponding beneficial relationship between the xylan (XYL) composition and flax fiber properties is presented. The correlation of GM and GGM contents in hemicellulose with flax fiber length was significant with R2 value 0.97 and 0.99, respectively. This study provides insight into the hydrolysis behavior of hemicellulose and a basis for developing scouring and/or bleaching models that can predict fiber properties.

Highly efficient fractionation of corn stover into lignin monomers and cellulose-rich pulp over H2WO4

In this work, we investigated the fractionation of raw biomass based on a “lignin-first” biorefinery strategy that enables the fractionation of corn stover into a stable lignin oil and a cellulose-rich pulp. Lignin fraction was completely disassembled into monomers with a yield of 25.1 wt% in methanol with a H2WO4 catalyst at 200 °C for 6 h. Higher temperature (≥220 °C) and longer reaction time (≥6 h) were in favor of higher delignification and hemicellulose removal, but led to lower cellulose retention and lignin monomer yield. Particle size of corn stover has minor impact on the delignification but significant for hemicellulose removal. A two-step mechanism is proposed for the fractionation of corn stover, in which ether and ester bonds between lignin and hemicellulose cleave to form oligomers through methanol solvolysis first, while the depolymerization of lignin oligomers to methyl hydroxycinnamates, e.g. methyl p-coumarate and methyl ferulate, as the major products happens in the catalytic steps.

Lower temperature hydrothermal pretreatment improves the anaerobic digestion performance of spent cow bedding

Abstract The anaerobic digestion (AD) performance of spent cow bedding was investigated with different hydrothermal pretreatment (HP) conditions. Spent cow bedding was pretreated with low temperatures (50, 70, and 90°C) and different pretreatment times (2-72 h) with ammonia and without ammonia. The results showed that spent cow bedding was a good raw material for AD. After pretreatment, the concentration of volatile fatty acids (VFAs) in the group of hydrothermal pretreatments with ammonia (HPA) was higher than that in the HP group at the same pretreatment temperature and time. The optimal pretreatment condition was achieved with an HPA of 50℃ holding for 72h. At the optimal condition, the highest concentration of VFAs was 1.58-10.85 times higher than that of the other pretreated groups. The highest hemicellulose and lignin removal rates were 58.07% and 10.32%, respectively. The highest methane yield was 163.0 ml·(g VS)-1, which was 48.9% higher than that of the untreated group. The VFAs, pH, and reducing sugars showed positive relationships with the methane yield. Therefore, HP at low temperature can enhance the AD performance of spent cow bedding.

Uniqueness of biphasic organosolv treatment of soft- and hardwood using water/1-butanol co-solvent

Biphasic organosolv treatment for soft- and hardwood using water/1-butanol was unique based on the correlation between liquid-phase states and solubility of the co-solvents when compared with a monophasic water/ethanol system. First, Pro II process simulator showed that water/1-butanol exhibited a biphasic system in the range of 1.6–19.0 mol/mol at a treatment temperature of 473 K. In addition, solubility of the co-solvents was evaluated using the Hildebrand solubility parameter (δ), which indicated that the biphasic system could simultaneously provide 28.5 and 42.0 MPa1/2 for the 1-butanol and water phase, respectively. Each δ value appeared appropriate for lignin and hemicellulose dissolution because they were similar to those reported for lignin and a typical sugar. While hemicellulose could be removed by increasing water content in an organosolv of Japanese cedar sawdust, high lignin removal was achieved only under biphasic conditions. Carbon yield of each fraction (solid, 1-butanol-, and water-soluble fraction) and Py-GC/MS analysis revealed that lignin and hemicellulose could be recovered in the 1-butanol and water fractions, respectively. The organosolv using Japanese cedar and willow was compared to the results when using monophasic water/ethanol. The results indicated that the co-solvent could not efficiently remove hemicellulose and lignin simultaneously because the monophasic system did not produce the level of solubility needed under the same conditions. In contrast, the biphasic water/1-butanol system achieved greater removal of hemicellulose and lignin compared to water/ethanol. The biphasic system was also applicable to separation of an industrial agricultural waste; sugarcane bagasse. Finally, the 2D-NMR spectra of 1-butanol-soluble lignin showed a trace amount of β-O-4 linkages in the lignin, indicating β-O-4 was cleaved via hydrolysis in the water phase during biphasic treatment.

Production of high concentration bioethanol from reed by combined liquid hot water and sodium carbonate-oxygen pretreatment

This study aimed to establish a method of producing high-concentration bioethanol from reed with reduced distillation-energy demand. Reed was subjected to a pretreatment combining liquid hot water (LHW) and sodium carbonate with oxygen (LHW–Na2CO3/O2) to increase substrate concentration and further achieve high bioethanol concentration through fed-batch semi-simultaneous saccharification and fermentation (fed-batch S-SSF). An oxygen pressure of 0.8 MPa, a Na2CO3 dosage of 16%, a reaction temperature of 160 °C, and a reaction time of 60 min were determined to be optimal, resulting in the highest bioethanol concentration (66.5 g L−1). Bioethanol concentration increased by 75.9% and resulted in a 76.6% decrease in distillation energy compared with those obtained by single-stage LHW pretreatment at 170 °C. After the LHW–Na2CO3/O2 pretreatment, the rate of lignin removal was 71.4%, and almost all hemicellulose was removed. Lignin and hemicellulose removal weakened the interactions among cellulose, hemicellulose, and lignin. We focused on the maximum utilization of biomass resources and decrease in energy expenditure, which highlighted the potential use of the combined LHW–Na2CO3/O2 pretreatment with fed-batch S-SSF method in the industrialization of bioethanol production from reed.

Effects of sulfuric acid promoter on biopolymer-derived fractions from empty plam fruit bunch under solvothermal fractionation process

A single step sulfuric acid catalyzed (H2SO4) under the organosolv process was studied for fractionation of empty palm fruit branches. The use of H2SO4 as an acid catalyst showed higher efficiency of the removal of hemicellulose with an increase in lignin removal from native EPFB into organic phase and leave glucan in solid fraction. The optimal condition showed the maximum glucan yields of 2.45 g and the highest lignin yields of 1.86 g was at 180oC, with 15 min residence time. The addition of H2SO4 catalyzed enhanced hemicellulose and lignin removal. 0.05% H2SO4 led to improve glucan yields of 3.17 g with the lower degradation of glucan and pentose in the aqueous phase. Under this condition, a 1.28 g recovery of lignin was obtained from the organic phase. Physicochemical analysis revealed intact cellulose fibers with the decrease in crystallinity, while the hemicellulose was partially recovered as mono- and oligomeric sugar. High-purity organosolv lignin with < 2% sugar cross-contamination was obtained with no major structural modification according to Fourier-transform infrared spectroscopy. This work represents an alternative process for efficient fractionation of lignocellulosic biomass in biorefineries.

Influence of Chemical Treatment and Moisture Absorption on Tensile Behavior of Neem/banana Fibers Reinforced Hybrid Composites: An Experimental Investigation

ABSTRACT Hybrid composites composed of neem fiber (N), banana (B) fiber and epoxy resin were fabricated by hand layup method. Three types of composites with blending ratio of B:N (1:4), B:N (1:1) and B:N (4:1) respectively were fabricated and the effects of fiber loading, chemical treatment and moisture absorption on tensile strength of the composites were investigated. The results showed that the fiber loading influenced the tensile strength and the B:N (4:1) composite displayed the superior tensile strength of 52 MPa compared to other composites due to the presence of more amount of banana fiber with high strength. The B:N (1:4) composite exhibited the lowest tensile strength of 47 MPa owing to the presence of more amount of neem fiber with low strength. Chemical treatment of fiber surface improved the tensile strength significantly due to the removal of impurities, lignin and hemicellulose. Silane-treated composite showed the greater tensile strength compared to alkali treated and untreated composites. Silane treated B:N (4:1) composite exhibited 17.5% and 42.3% improvement in tensile strength compared to the tensile strength of alkali treated and untreated composites respectively. Moisture absorption study revealed that the moisture uptake behavior of composite reduced the tensile strength due to the breakage of H-bond. Moisture absorption reduced the tensile strength of B:N (1:4), B:N (1:1) and B:N (4:1) composites by 14.7%, 10% and 5.8% respectively compared to dry samples.

Effect of Catalyst-Assisted Hydrothermal/Organosolv Process for Fractionation of Parawood

Fractionation of lignocellulosic components is a pre-requisite in biorefineries in order to separate the main compositions of raw material for further maximum utilization to biofuels, chemicals, and materials. Generally, a single step process is often insufficient to assure full availability of polymeric sugars from raw material. Therefore, the purpose of this study is to investigate two-step fractionation comprising hydrothermal and organosolv processes for the efficient separation of lignocellulosic biomass with a promising recovered yield in terms of quality and quantity. In this study, the effects of acids and bases concentration were studied in the two-step fractionation process, since they play different important roles in separation process. It was observed that the optimal condition of hydrothermal process was performed at 180°C for 60 min in the presence of 3.3%(w/w) of H2SO4 followed by organosolv process at 200°C for 60 min with 5%(w/w) of NaOH, resulting in the efficiency of hemicellulose and lignin removal of 87.96% and 46.39%, respectively. In addition, the high recovery of hemicellulose as pentose sugars were observed. The remaining cellulose was obtained with 80.22%. These results demonstrated the successive hydrothermal and organosolv process for fractionation of Parawood.

Enhancement of biomass conservation and enzymatic hydrolysis of rice straw by dilute acid-assisted ensiling pretreatment

To reduce the cost of lignocellulosic pretreatment, rice straw was ensiled with dilute formic acid (FA, 0, 0.2, 0.4, and 0.6%) for 3, 6, 9, 15 and 30 days, and evaluated its effects on fermentation dynamics, lignocellulosic degradation and enzymatic hydrolysis. The results showed that the application of FA, especially at 0.6% level, reduced total fermentation losses of the resulting silages, as evidenced by low dry matter loss, ammonia nitrogen and ethanol content. Meanwhile, the 0.6% FA application promoted hemicellulose removal (232.41 vs 187.52 g/kg DM) and xylose production (0.35 vs 2.80 g/kg DM). The glucose yield and cellulose convertibility of rice straw increased after 30 days of ensiling, and further enhanced by the 0.6% FA application. In conclusion, the 0.6% FA-assisted ensiling pretreatment improved both biomass preservation, hemicellulose removal and enzymatic hydrolysis of rice straw, which is beneficial to the subsequent biofuel production chain.

Enhancing cellulose nanofibrillation of eucalyptus Kraft pulp by combining enzymatic and mechanical pretreatments

Nanofibrillated cellulose (NFC) extracted from biomass has potential applications in material science and biomedical engineering. In this study, NFC was obtained from bleached eucalyptus Kraft pulp (BEKP) using two commercial enzyme cocktails with cellulolytic and hemicellulolytic activities and non-catalytic protein (swollenin), followed by ultrasonication. This work represents an initial study of the implementation of non-catalytic proteins along with enzymes to extract NFC from biomass. Enzymatic pretreatment was performed to partially remove hemicellulose while enhancing cellulose accessibility for NFC extraction. Cellulase pretreatment with xylanase and swollenin supplementation increased cellulose accessibility and fiber swelling due to extensive hemicellulose removal (> 80%) and fiber morphology changes. Subsequent ultrasonication was performed for cellulose nanofibrillation resulting in high NFC yields (61–97%), while keeping NFC properties almost unchanged. Through this process, cellulose nanofibers with diameters ranging from 3 nm to 10 nm were effectively isolated from BEKP, which allows to produce high quality NFC for further applications.

Effect of sequential pretreatment combinations on the composition and enzymatic hydrolysis of hazelnut shells

Hazelnut shells, a high lignin containing biomass, were subjected to individual and sequential liquid hot water (LHW), alkaline (AP) and dilute acid pretreatments (DAP). Among the single pretreatments, LHW demonstrated the highest cellulose recovery of 98.1%, DAP resulted in the highest hemicellulose solubilization of 56.0%, and AP of the highest lignin removal of 49.6%. Employing two-step pretreatment on hazelnut shells, in general, demonstrated an enhanced action of the second pretreatment; therefore, the sequence of the pretreatment methods had a significant impact on both substrate characteristics and enzymatic hydrolysis efficiency of biomass. In terms of delignification, AP-LHW achieved 60.7% lignin removal, while LHW-DAP showed the highest hemicellulose removal of 93.8% and DAP-LHW resulted in the highest cellulose recovery of 94.0%. Structural properties of raw and pretreated hazelnut shells were observed by FTIR. The maximum glucose recovery of 54.9% was observed in DAP-LHW pretreated samples. For this pretreatment combination, almost 1.8 MJ total energy was required to recover 10.2 g glucose. The findings indicated that complete removal of the physical barrier of lignin and hemicellulose might not be essential; partial relocation of lignin and alteration of cellulose structure may also be efficient in increasing the sugar recovery from the lignocellulosic biomass.