Energy Cane Bagasse Research Articles

Green Synthesis of Silver Nanoparticles from Energy Cane Bagasse Hydrolysate: Antimicrobial and Antibiofilm Properties

Green Synthesis of Silver Nanoparticles from Energy Cane Bagasse Hydrolysate: Antimicrobial and Antibiofilm Properties

A Multiomics Perspective on Plant Cell Wall-Degrading Enzyme Production: Insights from the Unexploited Fungus Trichoderma erinaceum.

Trichoderma erinaceum is a filamentous fungus that was isolated from decaying sugarcane straw at a Brazilian ethanol biorefinery. This fungus shows potential as a source of plant cell wall-degrading enzymes (PCWDEs). In this study, we conducted a comprehensive multiomics investigation of T. erinaceum to gain insights into its enzymatic capabilities and genetic makeup. Firstly, we performed genome sequencing and assembly, which resulted in the identification of 10,942 genes in the T. erinaceum genome. We then conducted transcriptomics and secretome analyses to map the gene expression patterns and identify the enzymes produced by T. erinaceum in the presence of different substrates such as glucose, microcrystalline cellulose, pretreated sugarcane straw, and pretreated energy cane bagasse. Our analyses revealed that T. erinaceum highly expresses genes directly related to lignocellulose degradation when grown on pretreated energy cane and sugarcane substrates. Furthermore, our secretome analysis identified 35 carbohydrate-active enzymes, primarily PCWDEs. To further explore the enzymatic capabilities of T. erinaceum, we selected a β-glucosidase from the secretome data for recombinant production in a fungal strain. The recombinant enzyme demonstrated superior performance in degrading cellobiose and laminaribiose compared to a well-known enzyme derived from Trichoderma reesei. Overall, this comprehensive study provides valuable insights into both the genetic patterns of T. erinaceum and its potential for lignocellulose degradation and enzyme production. The obtained genomic data can serve as an important resource for future genetic engineering efforts aimed at optimizing enzyme production from this fungus.

Assessment of energy cane bagasse-derived cellulosic microfiber hydrogels on the growth of potted chili peppers

Energy cane (Saccharum spp.) bagasse, a type of biomass waste, is often underutilized, burned, or left to dispose of itself. This research aimed to evaluate the potential of converting this bagasse into high-value cellulosic microfiber hydrogels (CMH) for water conservation and potted chili (Capsicum annuum) plant growth. CMH offers a biodegradable alternative to synthetic polyacrylamide (PA) hydrogels and provides the dual benefit of improved water use efficiency and reduced environmental impact due to their ability to naturally break down in the soil. In this study, CMH and PA hydrogels were compared for water retention value (WRV), and reswelling kinetics (RK), as well as their effects on plant height, leaf count, root-to-shoot ratios (R:S ratio), and soil moisture retention. Two versions of CMH, CMH65 and CMH60, were prepared with varying cellulose-chitosan ratios: 65:35 and 60:40, respectively. The hydrogels were tested at four concentrations (0, 0.5, 1.0, and 2.0% w/w) by being mixed in Promix® soil. Observations were recorded over a 16-day period without additional water. Also, the WRV of hydrogels at 240 min and RK (10–180 min) were compared over three swelling-deswelling cycles. The PA hydrogel exhibited higher WRV (exceeding 450%) compared to CMH (45%). However, PA led to reduced plant height, leaf count, and R:S ratio when compared to higher concentrations of CMH65 and CMH60. In general, CMH60 (0.5% and 2%) exhibited superior plant growth. All hydrogels exhibited a significant decrease (p < 0.05) in WRV across successive cycles. Notably, during cycle 2, both CMH65 and CMH60 peaked in WRV at 10 and 20 min, respectively, compared to cycle 1. This study demonstrates the potential of bagasse-derived hydrogels as a value-added product for water conservation and crop growth.

Pyrolysis of Energy Cane Bagasse: Investigating Kinetics, Thermodynamics, and Effect of Temperature on Volatile Products

Energy cane is a genotype derived from species of sugarcane (Saccharum officinarum and Saccharum spontaneum) with a lower sucrose content and higher fiber content for bioenergy purposes. It is a rustic plant that demands less fertile soils that do not compete with food crops. In this work, an analysis of energy cane bagasse pyrolysis products was performed, assessing the effect of reaction temperature and kinetic and thermodynamic parameters. Anhydrosugars, such as D-allose, were the primary compounds derived from the decomposition of energy cane at 500 °C. Methyl vinyl ketone and acetic acid were favored at 550 and 600 °C. At 650 °C, methyl glyoxal, acetaldehyde and hydrocarbons were favored. Among the hydrocarbons observed, butane, toluene and olefins such as 1-decene, 1-undecene, 1-tridecene and 1-tetradecene were the most produced. The Friedman isoconversional method was able to determine the average activation energies in the ranges 113.7−149.4, 119.9−168.0, 149.3−196.4 and 170.1−2913.9 kJ mol−1 for the decomposition of, respectively, pseudo-extractives, pseudo-hemicellulose, pseudo-cellulose and pseudo-lignin. The thermodynamic parameters of activation were determined within the ranges of 131.0 to 507.6 kJ mol−1 for ΔH, 153.7 to 215.2 kJ mol−1 for ΔG and −35.5 to 508.8 J mol−1 K−1 for ΔS. This study is very encouraging for the cultivation and use of high-fiber-content energy cane bagasse, after sucrose extraction, to produce biofuels as an alternative to the current method of conversion into electricity by low-efficiency burning.

Lignin-containing cellulose nanomaterials produced by microwave-assisted deep eutectic solvent treatment as rheology modifiers for fracturing fluids

Fracturing fluids used hydraulic fracturing in energy industry are formulated to have superior rheological properties for suspending and transporting rigid proppants into the fractures. Herein, we report the utilization of lignin-containing cellulose nanomaterials (LCNMs) to enhance the rheological properties of viscoelastic fracturing fluids (VFFs) based on borax-crosslinked guar gum (GG) gels. Two types of LCNMs, i.e., lignin-containing cellulose nanofibers (LCNFs) from energy cane bagasse and nanocrystals (LCNCs) from bleached wood pulp were manufactured using microwave-assisted deep eutectic solvent (MV-DES, choline chloride and lactic acid) pretreatment combined with high-pressure homogenization (HPH). The resultant LCNFs and LCNCs showed fibril- and rod-like morphology with lignin content of 13.7 % and 5.9 %, respectively; and their suspensions exhibited the typical shear-thinning behaviors and gel-like viscoelastic properties. Benefited from the superior rheology of LCNMs and hydrogen bonding formed between LCNMs and GG, the presence of LCNMs significantly increased the zero-shear viscosity, yield stress, shear-thinning capacity as well as thermal stability of GG-VFFs. LCNM/GG-VFFs exhibited outstanding proppant-suspending capacity as demonstrated by sand particles being uniformly dispersed in the fluids without settling after standing for 24 h at 25 and 80 ℃. • The morphologies of lignin-containing cellulose nanomaterials (LCNMs) are affected by the lignin content in origins. • LCNMs are utilized as rheology modifiers in the guar gum-viscoelastic fracturing fluids (GG-VFFs). • GG-VFFs with the addition of LCNMs exhibited outstanding proppant-suspending capacity.

Lignin-containing cellulose nanofibers made with microwave-aid green solvent treatment for magnetic fluid stabilization

Lignin-containing cellulose nanofibers (LCNFs), prepared from energy cane bagasse (ECB) using microwave-assisted natural deep eutectic solvent (MW-NADES) pretreatment combined with microfluidization, are utilized as stabilizing agents for magnetic particles (MNPs) in magnetorheological fluids (MRFs). The as-prepared LCNFs helped suspend negatively charged MNPs in MRFs effectively due to the presence of physically entangled network of LCNFs and the electrostatic repulsion between LCNFs and MNPs. Consequently, the presence of LCNFs increased the viscosity, yield stress and dynamic moduli of MRFs within the entire magnetic field range (0–1 T). Moreover, the as-developed LCNF-MRFs exhibited superior magnetorheological properties, i.e., widely controllable viscosity, yield stress and dynamic moduli, rapid magnetic response, good reversibility and outstanding cycling stability. This work demonstrates the sustainable, ultrafast production of LCNFs from cellulosic biomass using MW-NADES for MRF stabilization, paving the way for the development of high-performance, and eco-friendly MRFs.

Secretome analysis of Trichoderma reesei RUT-C30 and Penicillium oxalicum reveals their synergic potential to deconstruct sugarcane and energy cane biomasses

The conversion of lignocellulosic polymers into monomeric sugars demands a plethora of enzymatic activities generally not produced by a single microorganism and induced by the carbon source. In this vein, this work investigates the synergy between the enzymes secreted by the cellulolytic model fungi Trichoderma reesei RUT-C30 (TR) and Penicillium oxalicum (PO) to deconstruct sugarcane straw (SCS) and energy cane bagasse (ECB). TR and PO secrete a similar profile of cellulose-active enzymes resulting in a comparable conversion of SCS and ECB into glucose. The synergy between the enzymes produced by both fungi to break down the cellulose fraction becomes evident by the improvement of glucose titers from ~35–54% and from ~10–17% in SCS and ECB conditions, respectively, reached with the mixture of the secretomes of both fungi. The effect of a hemicellulase-enriched secretome produced by TR is particularly seen in SCS where the xylose yield reached ~15% compared to 5% by PO, remaining unaltered following the mixture of secretomes. However, the secretion of enzymes active in the decorations of the main chain polymers possibly aid PO to access the hemicellulose fraction of ECB reaching xylose yields similar to TR in this condition.

Correlating biomass properties, gasification performance, and syngas applications of Brazilian feedstocks via simulation and multivariate analysis

Biomass gasification is the thermochemical conversion of biomass mainly into syngas, and sugarcane bagasse (SCB) is its main feedstock in Brazil. However, the seasonal production of SCB influences biomass supply. This paper analyzed, via multivariate analysis, gasification datasets of 12 Brazilian feedstocks obtained from simulation to determine possible substitutes for SCB, optimal gasification conditions for all biomasses aiming at FT synthesis downstream, and key parameters for several syngas applications. A validated simulation in Aspen Plus™ of a fluidized bed gasifier generated one dataset with fixed gasification conditions used in hierarchical cluster analysis (HCA) and principal component analysis (PCA), and another with varying temperatures and S/B to obtain regression models via partial least squares (PLS) for optimization and Monte Carlo simulations. HCA and optimization using PLS models showed that sugarcane straw, energy cane, energy cane bagasse, and corn straw have similar gasification performances as SCB, being possible substitutes. Independent thermochemical plants based on eucalyptus, or corn and soybean straws are also suggested. Lignin is mostly useful for heat and power applications. PCA and HCA highlighted important correlations between inputs and outputs. Monte Carlo simulations suggested biomasses of lower C and higher O contents to obtain syngas suitable for FT synthesis and the opposite for applications of higher syngas heating values.

Balancing sugar recovery and inhibitor generation during energycane processing: Coupling cryogenic grinding with hydrothermal pretreatment at low temperatures

Pretreatment of lignocellulosic biomass at high temperatures or with oxidizing chemicals generate various inhibitors that restrict the efficient bioconversion of sugars in subsequent steps. The present study systematically investigates individual and combinatorial effects of pretreatment parameters on the generation of inhibitors. A plot between pretreatment temperature and inhibitor revealed optimum pretreatment temperature for energycane bagasse i.e., 170 °C beyond which total inhibitor production increased exponentially. No inhibitor production was observed on mechanical processing i.e., disk milling/cryogenic grinding of biomass. Evaluation of response surface regression exhibited that biomass solids loading has a significant effect on inhibitor generation at higher temperatures. The concentrations of certain inhibitors such as acetic acid, furfurals, and HMF increased more than 3-folds on doubling the solids loading. Furthermore, a novel low-severity approach of low-temperature hydrothermal pretreatment coupled with cryogenic grinding for lignocellulosic biomasses has been introduced which improved sugar yields while maintaining a low inhibitor concentration.

Prebiotics from energy cane bagasse

Xylooligosaccharides (XOS) is a group of emerging prebiotics that selectively stimulate the growth of advantageous gastrointestinal bacteria benefitting the host’s gut health and functionality. XOS can achieve positive biological effects at low daily doses and low caloric content, properties that are the same or more desirable than the already established prebiotics. XOS are present in plants in very low amounts so there is a great opportunity to isolate XOS with varying degrees of polymerization from the hemicellulose (xylan) fraction of lignocellulosic materials (e.g., bagasse), a source that offers both economic and environmental advantages. In this study, the recovery of XOS by the combined use of activated carbon adsorption, water washing and ethanol desorption from diluted acid pretreated energy cane bagasse hydrolysates was evaluated. The recovered XOS was tested for its prebiotic activity on Bifidobacterium adolescentis ATCC 15703. The final product of extracted XOS from energy cane bagasse (XOS EC Bagasse crude sample) had a purity of 93%, which was comparable to the purities observed with two commercially available XOS prebiotics, CPA (89%) and CPB (93%). XOS EC Bagasse crude sample exhibited prebiotic properties by stimulating the growth of B. adolescentis ATCC 15703 and by producing lactic acid, which were comparable to those observed with the commercial prebiotics.

Rapid Preparation of Cellulose Nanofibers from Energy Cane Bagasse and Their Application as Stabilizer and Rheological Modifiers in Magnetorheological Fluid

Magnetorheological fluids (MRFs) are smart fluids made of magnetic particles in a viscous carrier fluid, and their rheological properties are controllable by an external magnetic field. However, MRFs suffer from serious sedimentation and redispersibility problems, which limit their effectiveness and feasibility in a wide variety of applications. Herein, we present a novel strategy to improve magnetorheological property and stability of MRFs using cellulose nanofibers (CNFs), rapidly prepared from energy cane bagasse using microwave-assisted alkali-H2O2 and ultrasonic treatment. High delignification rate of 94.3% was achieved by the microwave treatment for 15 min. Chemical structure analysis revealed that the removal of lignin and carboxylation of cellulose occurred simultaneously. The obtained CNFs exhibited a highly entangled network structure, and their suspension showed the gel-like viscoelastic behavior. In CNF-MRF, the magnetic particles were entrapped and suspended by the entangled network of CNFs, which is due to the physical entanglement and the electrostatic repulsion force between Fe3O4 and CNFs. CNFs helped suspend magnetic particles in CNF-MRFs, leading to improved stability and magnetorheological properties (i.e., viscosity stability after cycling, reversible rate of 95.57% after 100 cycles). This work demonstrates a new path for the production of CNFs from energy cane bagasse wastes and their value-added utilization in MRFs.

Assessing the effects of cellulose-inorganic nanofillers on thermo/pH-dual responsive hydrogels

The incorporation of renewable bio-based materials/eco-friendly inorganic nanofillers into stimuli-responsive hydrogels meets the need for biocompatible and non-toxic functional materials. However, it remains challenging to build a three-dimensional network with enhanced mechanical properties and desired stimuli-responsive performances. In this study, dual stimuli-responsive hydrogels with interpenetrating polymer network structure are fabricated by the crosslinking of N-isopropylacrylamide (NIPAM)11NIPAM: N-isopropylacrylamide and sodium alginate (SA)22SA: Sodium alginate. 2,2,6,6-tetramethyl-piperidine-1-oxyl-oxidized cellulose nanofibers (TOCNF)33TOCNF: 2,2,6,6-tetramethyl-piperidine-1-oxyl-oxidized cellulose nanofibers derived from energycane bagasse serves as a carrier material for nanosilicas (NS)44NS: Nanosilicas and nanoclays (NC)55NC: Nanoclays and the effects of TOCNF, TOCNF/NS and TOCNF/NC on the hydrogels are thoroughly explored. Among these hydrogels, PNIPAM/SA-TOCNF-NS possesses the largest compressive strength of 66.7 kPa and it is 5.65 times higher than that of PNIPAM/SA. The thermo-sensitivity and pH-sensitivity of hydrogels are evidenced by swelling behaviors, optical properties, contact angle measurements and fluorescence tests. PNIPAM/SA-TOCNF exhibits the largest contact angle and the swelling processes for all the hydrogels are well fitted by pseudo-second-order swelling kinetic model. In addition, after incorporating carbon quantum dots, all the hydrogels display temperature dependent on–off fluorescence properties and this process are fully reversible with the heating and cooling cycles. These novel hydrogels with pH and temperature responsive characteristics and remarkable mechanical properties will open the door for interesting applications in smart sensors etc.

Production of lignin-containing cellulose nanofibers using deep eutectic solvents for UV-absorbing polymer reinforcement

Lignin-containing cellulose nanofibers (LCNFs) from energy cane bagasse (ECB), were prepared using microwave assisted deep eutectic solvent (MV-DES) treatment in combination with ultrasonication. The yield of lignocellulose is up to 45.2 % with 81.0 % delignification under the optimal reaction condition (110 ℃, 30 min). The resulting LCNF exhibited a highly entangled network, which was caused by the binder role of lignin between cellulose nanofibers. The addition of LCNFs improved the stability of the polyanionic cellulose (PAC) film-forming suspension, which was confirmed by the increased zeta potential and viscosity values. The LCNF / PAC films showed tunable mechanical and UV-resistant properties, depending on the amount and type of LCNFs. PAC films with the addition of 5 % LCNFs (PEF-5 %) showed good mechanical properties (a tensile strength of 55.8 MPa with a 26.3 % strain to break) and high UV protection ability (a UV-transmittance of 2.9 %).

Cellulose nanofibers from rapidly microwave-delignified energy cane bagasse and their application in drilling fluids as rheology and filtration modifiers

Energy cane bagasse (ECB) is the major residue after the cane is milled to extract juice for sugar, biochemical, and/or biofuel production. The sustainable conversion of ECB into high value-added products can help reduce agricultural waste, and enhance utilization of bioresources. In the present work, we demonstrate that ECB can be converted into cellulose nanofibers (CNFs) that can serve as high value-added additives in bentonite water-based fluids (BT-WDFs). Particularly, cellulose fibers (CFs) were rapidly isolated from ECB by microwave-assisted NaOH / NaClO2 treatments. CFs treated with the higher NaOH concentration and microwave irradiation lost more lignin (96.2 % delignification) and their crystal structure was more completely transformed from cellulose I to II, resulting in smaller diameters (8.5 μm). CNFs suspensions from subsequent wet-grinding and microfluidization of the CFs exhibited typical shear-thinning behaviors and solid-like viscoelastic properties due to the entangled network structure of the CNFs. Formulated fluids with 0.5 wt% of the manufactured CNFs showed good rheological and filtration properties, demonstrating their potential applications in the oil service industry.

Fumaric Acid Production by Rhizopus oryzae ATCC® 20344™ from Lignocellulosic Syrup

Powdered activated carbon-treated lignocellulosic syrup prepared from energy cane bagasse was evaluated as a potential feedstock in the production of fumaric acid by Rhizopus oryzae ATCC® 20344™. Energy cane bagasse was pretreated with dilute ammonia and enzymatically hydrolyzed with commercially available enzymes, Cellic® CTec2 and HTec2. The collected hydrolysate samples were subjected to powdered activated carbon adsorption for the removal of non-sugar compounds (i.e., organic acids, furaldehydes, total phenolic compounds) and concentrated to a final 65°Bx syrup (mostly xylose and glucose sugars). The use of lignocellulosic syrup, the effect of nitrogen source, medium additives, and initial pH in the seed culture medium on fungal morphology were investigated. The carbon to nitrogen (C/N) ratio in the acid production medium was also optimized for maximum yields in fumaric acid production. Optimum seed culture medium conditions (2.0 g/L urea, 3.0 pH) produced the desired compact, smooth, and uniform fungal pellets. Optimum acid production medium conditions (400 C/N ratio, 0.2 g/L urea) resulted in a fumaric acid production of 34.20 g/L, with a yield of 0.43 g/g and a productivity of 0.24 g/L/h. These results were comparable to those observed with the control medium (pure glucose and xylose). The present study demonstrated that lignocellulosic syrup processed from dilute ammonia pretreated energy cane bagasse has potential as a renewable carbon source for fumaric acid fermentation by Rhizopus oryzae ATCC® 20344™.

Optimization of activated carbon detoxification of dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate by response surface methodology

A challenge in syrup production from lignocellulosic biomass is the presence of non-sugar compounds in the hydrolysate, generated during the hydrolytic process, which negatively impact downstream processes. Energy cane bagasse was pretreated with ammonium hydroxide and then hydrolyzed with enzymes Cellic® CTec2 and HTec2. Non-sugar compounds such as formic acid, acetic acid, levulinic acid, furfural, 5-hydroxymethylfurfural (5-HMF), and phenolic compounds were formed during pretreatment and enzymatic hydrolysis. Activated carbon (AC) treatments were carried out to remove these non-sugar compounds while retaining the fermentable sugars, mostly glucose and xylose. Powdered AC and granular AC were compared and parameters including AC dose, hydrolysate pH and contact time were optimized using response surface methodology. Optimum conditions for powdered AC were 9.21% (w/w) dose, at pH 1.96 for 10 min, and for granular AC were 12.64% (w/w) dose, at pH 1.91 for 51.60 min. At these conditions, approximately 40% acetic acid, 75% formic acid and over 90% levulinic acid, HMF, furfurals, and phenolic compounds were removed with minimal fermentable sugar losses. Activated carbon adsorption can significantly reduce the non-sugar compounds present in the hydrolysate with minimal losses of fermentable sugars, which is beneficial in the production of lignocellulosic syrup and value-added products.

Interactive effect of enzymes and surfactant on the cellulose digestibility of un-washed and washed dilute ammonia pretreated energy cane bagasse

The interaction effect of cellulase (Cellic® CTec2), xylanase (Cellic® HTec2) and laccase along with a non-ionic surfactant (Tween® 80) on cellulose digestibility of unwashed and washed liquid ammonia pretreated energy cane bagasse was investigated. A polynomial quadratic model was fitted and solved for the optimum value of each variable for the desired response using response surface methodology (RSM). Statistical analysis of the results showed that the interactive effect of all variables with cellulose were significant (p < .05) and resulted in 75.85% and 12.74% improvement in cellulose digestibility of unwashed and washed biomass, respectively. Highest cellulose digestibilities observed were 84.30% and 97.10% for values set within the design range for the unwashed and washed biomass, respectively. Optimum enzymatic hydrolysis conditions for unwashed substrate were 19.39% (mass ratio of glucan) CTec2, 12.04% (mass ratio of glucan) HTec2, a laccase loading on dry biomass of 46.32 IU g−1, and 10.15% (mass ratio of biomass) Tween® 80. Optimum enzymatic hydrolysis conditions for washed substrate were 16.90% (mass ratio of glucan) CTec2, 14.17% (mass ratio of glucan) HTec2 (w/w), a laccase loading on dry biomass of 34.64 IU g−1, and 14.86% (mass ratio of biomass) Tween® 80.

Detoxification of dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate by soluble polyelectrolyte flocculants

This study investigated the detoxification of dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate using polyelectrolyte flocculants. Non-sugar compounds such as formic acid, acetic acid, levulinic acid, furfural, 5-hydroxymethylfurfural (HMF), and phenolic compounds can be generated during pretreatment, which have negative effects on downstream processes. Flocculation was carried out to remove these non-sugar compounds while retaining the fermentable sugars. The flocculants polyethylenimine (PEI) and poly-diallyldimethylammonium chloride (pDADMAC) were used and parameters including flocculant dose and hydrolysate pH were evaluated. The recyclability of PEI and recovery of non-sugar compounds were also assessed. Optimum conditions for both PEI and pDADMAC were 15 g/L dose at unadjusted pH 4.5. At these conditions, PEI outperformed pDADMAC by having greater adsorption efficiencies towards non-sugar compounds with minimal sugar losses. PEI removed 43% organic acids, 73% total phenolic compounds and 100% furans with less than 10% total fermentable sugar losses. However, after two cycles, only 20% of the adsorbed organic acids and total phenolic compounds, and 80% of the furans were recovered. Sugar losses of less than 10% were observed throughout the recycling process. PEI can significantly remove the non-sugar compounds from dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate with minimum sugar losses. However, recycling of PEI and recovery of adsorbed non-sugar compounds are not recommended for more than two cycles.

Optimization of liquid ammonia pretreatment variables for maximum enzymatic hydrolysis yield of energy cane bagasse

This study aimed at optimizing a liquid ammonium hydroxide pretreatment for energy cane bagasse for maximum sugar yields (glucose and xylose) via response surface methodology. Optimized pretreatment parameters included temperature (160–220°C), ammonium hydroxide to biomass ratio (0–0.5:1) and residence time (30–60min). Temperature was found to be the dominant pretreatment parameter followed by ammonium hydroxide to biomass ratio. High temperatures and long residence times had a negative effect on sugar yields. Sugar yields had the highest correlation with lignin removal. Based on our quadratic models fitted on the experimental results, optimum pretreatment conditions for maximum glucose yield were 208°C, for 36min and at an ammonium hydroxide to biomass ratio of 0.4:1. A glucose yield of 30.77g glucose/100g (dry weight) untreated biomass and a xylose yield of 3.99g xylose/100g (dry weight) untreated biomass were predicted by the model. Optimum pretreatment conditions for maximum xylose yield were 160°C, for 60min and at an ammonium hydroxide to biomass ratio of 0.31:1. These conditions resulted in a predicted xylose yield of 9.10g xylose/100g (dry weight) untreated biomass and a glucose yield of 23.34g glucose/100g (dry weight) untreated biomass. The low xylose yields observed were attributed to the high amounts of xylan lost due to solubilization. The quadratic models were found to be reliable for the prediction of sugar yields within the design space. All predicted values were experimentally confirmed with 95% confidence of the predicted values.

Cellulose nanofibers reinforced sodium alginate-polyvinyl alcohol hydrogels: Core-shell structure formation and property characterization

Core-shell structured hydrogels consisting of a flexible interpenetrating polymer network (IPN) core and a rigid semi-IPN shell were prepared through chemical crosslinking of polyvinyl alcohol (PVA) and sodium alginate (SA) with Ca2+ and glutaraldehyde. Short cellulose nanofibers (CNFs) extracted from energycane bagasse were incorporated in the hydrogel. The shell was micro-porous and the core was macro-porous. The hydrogels could be used in multiple adsorption–desorption cycles for dyes, and the maximum methyl blue adsorption capacity had a 10% increase after incorporating CNFs. The homogeneous distribution of CNFs in PVA-SA matrix generated additional hydrogen bonds among the polymer molecular chains, resulting in enhanced density, viscoelasticity, and mechanical strength for the hydrogel. Specifically, the compressive strength of the hydrogel reached 79.5kPa, 3.2 times higher than that of the neat hydrogel.