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Agricultural residues (e.g. corn stover (CS)) representing a huge lignocellulosic biomass waste are regarded as a promising renewable resource that can be converted to fuels and chemicals via biochemical route. Nevertheless, the unfavorable properties, such as low bulk density, contamination by microorganisms, fluffy and thereby difficult to handle, cause huge problems for biomass logistics and biomass conversion. Furthermore, traditional biomass pretreatment methods often use severe conditions, consume much energy, difficult to scale up and generate a feedstock with many toxic degradation products that inhibit fermentation. In this study, we developed a novel, low-cost and easy-to-implement pretreatment method: “Densifying Lignocellulosic biomass with acidic Chemicals (DLC)” on CS. The DLC-CS owning a uniform shape showed a bulk density 4 times higher compared to loose CS and was highly resistant to microbial contamination, which greatly facilitates biomass handling, transportation and storage. DLC-CS after regular steam autoclave treatment at 121 ○C exhibited high enzymatic digestibility and much higher fermentability compared to traditional dilute acid pretreatment. An ethanol titer as high as 68.1 g/L was achieved without washing or detoxification of the pretreated biomass. The superior performances of DLC for biomass logistics and biomass conversion render it very promising for industrial use.

Lignocellulosic biomass is a promising renewable feedstock for the sustainable manufacturing of biofuels and bioproducts. Among emerging bioproducts, 3-hydroxypropionic acid (3-HP) is of particular...

Organosolv lignins were extracted from corn stover, wheat, rice straw, reed straw, and sugarcane bagasse using a mixture of acetic and formic acids, at relatively low temperature and atmospheric pressure. Lignin content, residual carbohydrates, ash levels, proteins, and molecular weights were determined in each extracted lignin. The lignin content of all samples was relatively high, confirming the performance of the pretreatment process. The low molecular weights were in a narrow range, in accordance with the organosolv lignin molar masses. However, some differences between studied lignins were highlighted, in particular in rice straw lignin, which contained the highest silica, calcium, and nitrogen contents. Nuclear magnetic resonance spectroscopies (31P and semi-quantitative Heteronuclear Single Quantum Correlation) underlined the structural similarities and differences between these organosolv lignins. Corn stover and sugarcane bagasse lignins were rich in non-methoxylated (H-Unit) or mono-methoxylated (G-Unit) phenolic units, making them the best promising candidates for production of phenolic resins. Wheat straw lignin was richer in aliphatic OH than in phenolic OH. This is an advantage for use as polyol substitute in polyurethane synthesis. Reed straw lignin was less specific, with a balanced content of OH groups. However, it contained a high concentration of β-O-4 linkages, which is favorable for depolymerization.

In humid tropical environments, where soils are characteristically acidic and low in organic matter, lime and organic residues have been used to improve soil quality. A systematic consideration of their interaction is, therefore, crucial for land-based ecosystem management. A 28-day incubation pot study was carried out to investigate the main and interactive effects of lime and organic residue type (corn stover and vermicompost) on aggregate stability under rapid wetting (WSAr), saturated hydraulic conductivity (Ksat), and soil water repellency (SWR) on three acidic soils with contrasting clay content from Trinidad: Cunupia (Aquic Hapludalfs), Sangre Grande (Fluvaquentic Endoaquepts), and Talparo (Aquertic Eutrudepts). Organic residue had a significant (P ≤ 0.001) increasing effect on WSAr and Ksat for all three soils, this being highest for corn stover and lowest for no residue. Lime and organic residue interactive effects were only significant (P ≤ 0.05) for WSAr in the Cunupia soil, where lime significantly reduced WSAr in the vermicompost and no residue, but not in the corn stover treatment. Soil water repellency increased with clay content and was highest in the lime–corn stover treatment of the Talparo soil. Overall, our results suggest that applying crop residue with lime may help minimise the short-term deleterious effects of lime on the structural and hydraulic properties of humid tropical soils. Nonetheless, future experiments with a wider range of soils and organic residues need to be carried out for a longer term to validate our results.

To explore the effects of pretreatment methods including drying, vacuum freezing drying (VFD), pelleting, and ultrasonic vibration-assisted pelleting (UV-AP) on corn stover and biochar properties, the physicochemical and morphological changes of biomass before and after pretreatment were examined, and the effects of different pretreatment methods on biochar properties were investigated. The results showed that different pretreatment methods have a significant effect on the surface and internal structure of biochar. The highest and lowest specific surface area, micropore area, and total pore volume of biochar were 25.84 m2/g, 9.27 m2/g, 0.53 cm3/g, and 17.33 m2/g, 4.39 m2/g, 0.29 cm3/g, respectively. FTIR analysis showed that the functional group of pretreated corn stover was similar to those of biochar. Ultimate analysis indicated that both pretreatment methods and the highest treatment temperature had a significant effect on biochar compositions. The order of carbon content of biochar derived from different pretreatment methods was drying > VFD > UV-AP > pelleting. The biochar yield, enhancement factor, and energy yield were significant affected by pretreatment methods. By contrast, the biochar pH was alkaline and not significantly affected by pretreatment methods. These findings provide a reliable route to choose pretreatment methods for producing biochar with desired properties, which could be a guide for industrial application.

Biofuels in the form of bio-oil and biochar have been produced by microwave heating of corn stover. Different adsorbents such as silicon carbide (SiC) and activated carbon (AC) with different ratios (10%, 20%, and 30%) to corn stover are investigated with the aims of enhancing the absorption of the microwave, maximizing the yields of the desirable products i.e. bio-oil followed by biochar as well as improving their qualities. Use of both the adsorbents improved the heating performance through increase in the maximal temperature and heating rate by 170 °C and 36 °C/min respectively compared to without adsorbent. Use of AC increased the yield of bio-oil up to 45 wt% while SiC increased the gas yields up to a maximum value of 48 wt%. The better physical properties such as 37%, 5.3, 2.9 mPa s, and 1 g/mL for water content, pH, viscosity and density respectively of bio-oil were obtained when using AC as an adsorbent. Also, use of AC helped in producing bio-oils which contained higher carbon and hydrogen contents as well as high calorific value (17 MJ/kg). Similarly, use of AC increased the contents of hydrocarbons and phenols in the bio-oil up to 36% and 28% respectively with low oxygen-containing compounds (2%). Also, use of AC produced the biochar having cleanest pores that were almost free of carbon-like impurities with a higher surface area of the pore (105.2 m2/g). In addition, biochar having low ash content, high carbon content, and calorific value (28 MJ/kg) were achieved. The net energy recovery with respect to raw corn stover was calculated to be of maximum value i.e., 55% when using AC. The AC and SiC were reused for further runs of the experiments (5 times) with few changes in the heating behavior and the yields of the pyrolytic products.

Corn stover is one of the dominant agricultural wastes in China, with high lignocellulose contents. Anaerobic digestion of corn stover converts biomass to biogas as sustainable energy. To improve the performance of anaerobic digestion, as well as for flexible biogas production, the effects of different feeding regimes on biogas production, system stability, and microbial community structure were investigated using laboratory-scale semi-continuously stirred tank reactors (semi-CSTRs) fed pretreated corn stover once a day (R1), every 2 days (R2) and every 3 days (R3) at an equivalent amount. The results showed that R3 and R2 produced 11.1% and 8.4% more methane, respectively. R3 correspondingly had higher lignocellulose conversion rates and system stability, followed by R2 and R1. Greater fluctuations in biogas, VFA concentrations and pH were found in less frequently fed reactors during the time interval between two feeds. Additionally, less feeding increased the relative abundance of Bacteroidetes and Firmicutes during hydrolysis and acidogenesis, and the dominant genus of archaea in all reactors was Methanobacterium, which is a hydrogenotrophic methanogen. Therefore, appropriately reducing the feeding frequency can increase the process performance of anaerobic digestion of corn stover.

Effects of soaking aqueous ammonia pretreatment on chemical composition and enzymatic hydrolysis of corn stover. The aim of this research was to investigate the effect of applying two different temperatures of the soaking aqueous ammonia treatment on the chemical composition and enzymatic hydrolysis yield of the corn stover. Native corn stover as well as solid fractions after 20 h of alkali pretreatment performed at 15% ammonia solution and at 50 °C or 90 °C were analysed in terms of cellulose, holocellulose, lignin and extractives content. Both untreated and treated samples were subjected to the enzymatic hydrolysis and hydrolysates were examined with a high performance liquid chromatography (HPLC). Results indicated a significant development of enzymatic digestibility of the SAA treated biomass. Furthermore, a 38.7% and a 68.9% delignification levels in the biomass treated with ammonia at respectively 50 °C and 90 °C process comparing to the raw material were achieved.

Exploring an efficient technique for carbon sphere preparation has attracted extensive attention. Herein, acidic lithium bromide hydrate (ALBH) was used in the hydrothermal carbonization (HTC) process to overcome the recalcitrance of lignocellulose, such that nano-carbon spheres were prepared at mild condition: 140 °C for 150 min with 0.8 M of HCl from 20-40 meshed corn stover. That carbon spheres showed decent morphology properties and abundant functional groups, which was better than that from pine and poplar wood. The corn stover derived carbon nanospheres could efficiently adsorb both heavy ions and methyl orange in wastewater. Meanwhile, the ALBH after reaction could be recovered and reused. Specifically, the morphologies and adsorption capability of the prepared carbon nanospheres using recovered ALBH were negligibly affected even after 5 cycles. These results verified the practical production of carbon nanospheres from lignocellulose at mild conditions, which provided more potential for the synthesis of novel biomass-based materials for comprehensive applications.

As a cheap, biodegradable, and nontoxic chemical, choline chloride (ChCl) is widely used in animal feed. In this study, acid and alkali catalyzed ChCl pretreatments of corn stover (CS) were investigated. Compared with single aqueous ChCl pretreatment, H2SO4 acidified aqueous ChCl pretreatment was more effective in removing lignin (69.5%) and xylan (84.9%). NaOH alkalified aqueous ChCl pretreatment demonstrated better performance of delignification (76.8%) but weaker capability of removing xylan (46.2%) than acidified aqueous ChCl pretreatment. Following enzymatic digestibility of pretreated CS, glucose yield from acidified ChCl pretreatment was 72.1%, significantly lower than that of alkalified ChCl pretreatment (89.4%). However, the highest glucose yield of 98.6% resulted from solitary alkali pretreatment. Correlation studies between change in physico-chemical properties of pretreated solids and corresponding enzymatic digestibility indicated high delignification and bigger cellulose crystallite size were mainly responsible for high enzymatic hydrolysis efficiency. Additionally, the properties of extracted lignin from single and combined pretreatments with ChCl and alkali or acid were analyzed. Acidified ChCl pretreatment increased, whereas alkaline ChCl pretreatment decreased molecular weight and phenolic hydroxyl groups of separated lignin in comparison to individual acid and alkali pretreatment. These findings would provide useful information in understanding biomass pretreatments with aqueous ChCl.

The aim of this study was to assess the effects of a biochar-based slow-release P fertilizer (BBSRPF) produced from a corn stover-derived biochar (CSB), compared to mineral fertilization and co-application of CSB itself and mineral fertilization on bioavailability of soil P and spinach production, as well as, foliar macronutrients (N, P and K), protein, and ascorbic acid in plants. First, CSB was produced from corn stover. Then, P loading process was done with a KH2PO4 solution for BBSRPF production. Afterwards, a greenhouse experiment was performed for 70 days using a factorial design with the following treatments: mineral NPK fertilization (F), CSB and mineral NPK fertilization (BC) and BBSRPF and mineral NK fertilization (P-BC). After this, soil samples were collected and the plants were harvested to determine changes in soil physicochemical properties, bioavailability of soil P, leaf content of P, N, K, ascorbic acid, and protein. Besides, fresh and dry biomass, and crop yield were also determined. The P-BC treatment significantly increased bioavailable soil P by ~ 72% compared to F and BC treatments. Furthermore, P, N, K, protein, ascorbic acid content, and yield of spinach pants were significantly increased by ~ 29, 52, 33, 20, 21, and ~ 25% when P-BC treatment was applied, respectively. Incorporation of P into the biochar matrix is an effective strategy to increase spinach P use efficiency in tropical soils. Therefore, BBSRPF could totally replace conventional mineral P fertilizers without compromising crop yield, and increasing the nutritional quality of spinach plants.

Pseudomonas putida is a highly solvent-resistant microorganism and useful chassis for the production of value-added compounds from lignocellulosic residues, in particular aromatic compounds that are made from phenylalanine. The use of these agricultural residues requires a two-step treatment to release the components of the polysaccharides of cellulose and hemicellulose as monomeric sugars, the most abundant monomers being glucose and xylose. Pan-genomic studies have shown that Pseudomonas putida metabolizes glucose through three convergent pathways to yield 6-phosphogluconate and subsequently metabolizes it through the Entner–Doudoroff pathway, but the strains do not degrade xylose. The valorization of both sugars is critical from the point of view of economic viability of the process. For this reason, a P. putida strain was endowed with the ability to metabolize xylose via the xylose isomerase pathway, by incorporating heterologous catabolic genes that convert this C5 sugar into intermediates of the pentose phosphate cycle. In addition, the open reading frame T1E_2822, encoding glucose dehydrogenase, was knocked-out to avoid the production of the dead-end product xylonate. We generated a set of DOT-T1E-derived strains that metabolized glucose and xylose simultaneously in culture medium and that reached high cell density with generation times of around 100 min with glucose and around 300 min with xylose. The strains grew in 2G hydrolysates from diluted acid and steam explosion pretreated corn stover and sugarcane straw. During growth, the strains metabolized > 98% of glucose, > 96% xylose and > 85% acetic acid. In 2G hydrolysates P. putida 5PL, a DOT-T1E derivative strain that carries up to five independent mutations to avoid phenylalanine metabolism, accumulated this amino acid in the medium. We constructed P. putida 5PLΔgcd (xylABE) that produced up to 250 mg l of phenylalanine when grown in 2G pretreated corn stover or sugarcane straw. These results support as a proof of concept the potential of P. putida as a chassis for 2G processes., MINECO (Grant / Award Number:’RTI2018-094370-B-I00)

Corn stover (CS) is mainly composed of three parts: pith (CSP), rind (CSR), and leaf (CSL). These parts have different lignocellulosic constituents and structural properties. Herein, biosorbents derived from individual corn stover constituents were prepared in an effort to determine the significance of each constituent for multipollutant removal. In this study, SEM, BET, XRD, FTIR, XPS, fibre composition, and contact angle measurements were used to characterize and analyse the physical and chemical properties of the three components of CS and to study their adsorption effects, adsorption isotherms, and kinetics. The lignocellulosic compositions of CSP and CSR were similar, the cellulose content in CSP and CSR was significantly higher than that in CSL, and the hemicellulose content of CSL was much higher than those of CSP and CSR. The minimum lignin content was found in CSP, and the maximum lignin content was found in CSR. The results show that each component had a certain adsorption effect on typical organic pollutants (antibiotics, oils, and dyes). CSP had the strongest oil adsorption capacity, CSR was more suitable for adsorbing antibiotics, and CSL had outstanding adsorption capacity for dye. The pseudo-second-order model and the Langmuir adsorption isotherm model could describe the adsorption processes well, and they consisted of monolayer adsorption accompanied by chemical adsorption reactions. The focus of this study was to provide references for selecting effective adsorbent precursors to remove organic pollutants from wastewater.

Effects of cellulase addition were assessed relative to the co-ensiling performance of air-dried corn stover (DCS) and cabbage waste (CW). The DCS and CW mixtures were co-ensiled with 0 to 0.3% of cellulase addition, and changes in composition, intermediates, and biological activity were characterized. The results showed that the addition of cellulase enhanced the decomposition of cellulose and hemicellulose by 2.51 to 6.93% and 3.41%, based on different dosages and compared with the control. Thus, the content of water-soluble carbohydrates increased. The acid content also increased from 5.8% for the control to the range 5.16 to 8.51% for the samples containing cellulase. Moreover, there was a shift from homolactic to heterolactic fermentation with prolonged ensiling time, coupled with the dominant lactic acid bacteria shifting from Paralactobacillus and Lactobacillus to more of Lactobacillus. Thus, the addition of cellulase improved the relative abundance of Lactobacillus. An assessment of fermentation quality, therefore, suggested that cellulase addition can improve the silage quality of DCS/CW during co-ensiling.

Chemical pretreatment of lignocellulosic biomass is a critical step in the conversion of lignocellulose to biofuels and biochemical. The main drawback of this pretreatment process is the formation of inhibitors which exhibit combined toxicity to microorganisms and result to low product concentrations and yields. In this study, the selection of microbial consortia by enrichment on hydrolysate of H2SO4-pretreated corn stover (pre-CS) without detoxification has been investigated as an efficient way to develop new strategies for lignocellulose utilization. The analysis of cattle stomach-dervied microbial consortia domesticated to degrade hydrolysate of pre-CS to produce lactic acid (LA) at different temperatures was investigated. Bacterial 16S rRNA gene amplicon sequencing analyses indicated that the three microbial consortia were taxonomically distinct and Enterococcus became dominant at high temperature. The highest glucose consumption rate was observed at 45 °C, while the three microbial consortia showed similar consumption rates of xylose and arabinose. The selected microbial consortia DUT37, DUT45 and DUT47 showed preferable resistances to inhibitors in hydrolysate of pre-CS and abilities of xylose utilization. A batch simultaneous saccharification and fermentation (SSF) process was developed by microbial consortium DUT47 at 47 °C to produce LA from pre-CS under non-detoxified and non-sterile conditions. The LA concentration and yield were 43.73 g/L and 0.50 g/g-corn stover (CS), respectively. Microbial consortium DUT47 has been shown to be suitable for LA production from H2SO4-pretreated corn stover without detoxification due to its thermophilic growth characteristics, robust tolerance of inhibitors, and the simultaneous utilization of glucose and xylose.

A study was carried out to investigate the characterization of a novel Aspergillus sulphureus JCM01963 xylanase (AS-xyn10A) with a carbohydrate binding module (CBM) and its application in degrading alkali pretreated corncob, rapeseed meal and corn stover alone and in combination with a commercial cellulase. In this study, the 3D structure of AS-xyn10A, which contained a CBM at C-terminal. AS-xyn10A and its CBM-truncated variant (AS-xyn10A-dC) was codon-optimized and over-expressed in Komagaella phaffii X-33 (syn. Pichia pastoris) and characterized with optimal condition at 70 °C and pH 5.0, respectively. AS-xyn10A displayed high activity to xylan extracted from corn stover, corncob, and rapeseed meal. The concentration of hydrolyzed xylo-oligosaccharides (XOSs) reached 1592.26 μg/mL, 1149.92 μg/mL, and 621.86 μg/mL, respectively. Xylobiose was the main product (~70%) in the hydrolysis mixture. AS-xyn10A significantly synergized with cellulase to improve the hydrolysis efficiency of corn stover, corncob, and rapeseed meal to glucose. The degree of synergy (DS) was 1.32, 1.31, and 1.30, respectively. Simultaneously, XOSs hydrolyzed with AS-xyn10A and cellulase was improved by 46.48%, 66.13% and 141.45%, respectively. In addition, CBM variant decreased the yields of xylo-oligosaccharide and glucose in rapeseed meal degradation. This study provided a novel GH10 endo-xylanase, which has potential applications in hydrolysis of biomass.

One of the highest costs in bio-butanol production is the separation of butanol from the fermentation broth, which is composed of acetone, butanol, and ethanol. Instead of using butanol, researchers experimentally investigated the utilization of the acetone-butanol-ethanol (ABE) mixture in gasoline and diesel engines to promising results. However, there has been no well-to-wheel (WTW) study to determine the life cycle energy balance and greenhouse gas (GHG) emissions that covers the entire production process and use of ABE as a transportation fuel. In this study, the WTW analysis of ABE from two feedstocks (corn and corn stover-based) and their benefits in replacing a portion of gasoline or diesel with ABE is investigated. Results show that ABE could achieve 56–80% fossil fuel savings and 53–83% GHG emission reductions when compared to both gasoline and diesel. The WTW analysis indicated that ABE from both feedstocks has the potential to become as an alternative biofuel directly and as an additive blend for diesel or gasoline.

Sodium carbonate pretreatment, an environmentally-friendly and efficient pretreatment, was used to improve solid-state ethanol production from corn stover (CS). To further enhance ethanol yield from the pretreated CS, especially at low enzyme loadings, a combined pretreatment, including steam and sodium carbonate pretreatments, was developed. The removal/modification of lignin by sodium carbonate pretreatment (at 100 °C for 3 h) helped to obtain high ethanol titer at high solids and low enzymes loadings. The maximum ethanol concentration was about 44 g/L, obtained after 72 h simultaneous saccharification and fermentation (SSF) of CS pretreated with sodium carbonate without mixing and prehydrolysis at 30% solid and 15 FPU/g enzyme loadings. Applying prehydrolysis and increasing the SSF time to 120 h improved ethanol concentration to 59 and 67 g/L, respectively. Steam pretreatment at 190 °C for 10 min before sodium carbonate pretreatment led to 76% increase in ethanol concentration. At the enzyme loading of only 5 FPU/g substrate, the modified pretreatment increased the ethanol concentration from 24 g/L to 41 g/L, compared with that of sodium carbonate pretreatment. The results showed that hemicellulose removal and delignification by steam and sodium carbonate pretreatment, respectively, considerably improved ethanol concentration at high solids and low enzyme loadings.

Four Pleurotus spp. fungi (P. diamor, P. eryngii, P. sajor-caju, P. citrinopileatus) were compared for their potential to improve nutritional value of corn stover as ruminant feed. Corn stover was inoculated with the fungi under solid-state conditions and their results showed that P. sajor-caju and P. eryngii were better than the other two species of Pleurotus with respect to decreasing the acid detergent lignin (ADL) (8.99 vs 9.88 vs 10.16 vs 10.46). In contrast, P. eryngii had lower ability to degrade cellulose (13.38%). Corn stover treated with P. citrinopileatus had the highest crude protein (CP) content (7.65%), whereas treatment with P. sajor-caju resulted in the highest increase in essential amino acids (55.11%). Although fungal pre-treatment of lignocellulosic biomass does not always result in high-quality feed, overall, P. eryngii and P. sajor-caju improved the nutritive value of corn stover as a ruminant feed.

Efficient cellulolytic enzyme production is important for the development of lignocellulose-degrading enzyme mixtures. However, purification of cellulases from their native hosts is time- and labor-consuming. In this study, a constitutive expression system was developed in Penicillium oxalicum for the secreted production of proteins. Using a constitutive polyubiquitin gene promoter and cultivating with glucose as the sole carbon source, nine cellulolytic enzymes of different origins with relatively high purity were produced within 48 h. When supplemented to a commercial cellulase preparation, cellobiohydrolase I from P. funiculosum and cellobiohydrolase II from Talaromyces verruculosus showed remarkable enhancing effects on the hydrolysis of steam-exploded corn stover. Additionally, a synergistic effect was observed for these two cellobiohydrolases during the hydrolysis. Taken together, the constitutive expression system provides a convenient tool for the production of cellulolytic enzymes, which is expected to be useful in the development of highly efficient lignocellulose-degrading enzyme mixtures.

The aim of this study is to develop and characterize an activated biochar-based polymer composite for biosensors in smart food packaging. Biochar was made from corn stover and activated using the s...

Xylanase plays a vital role in the efficient utilization of xylan, which accounts for up to 30% of plant dry matter. However, the production cost of xylanase remains high, and the enzymatic characteristics of xylanases of most microorganisms are not suitable for industrial production. Therefore, it is of great significance to discover and develop new and efficient xylanases. In this study, the xylanase gene TAX1 (672 bp cDNA) was cloned from Trichoderma atroviride 3.3013 and expressed in Pichia pastoris. The TAX1 gene encoded a 223-amino acid protein (TAX1) with a molecular weight of 24.2 kDa which showed high similarity to glycoside hydrolase family 11. Enzyme activity assay verified that the recombinant xylanase TAX1 had optimal activity (215.3 IU/mL) at 50°C and pH 6.0. Stable working conditions were measured as pH 4.0-7.0 and 40-60°C. By adding Zn2+, the relative enzymatic activity of recombinant TAX1 was enhanced by 26%. The recombinant xylanase showed high activity toward birchwood xylan and corn stover. The Km and Kcat for xylan and corn stover were 0.36 mg/mL and 0.204 S-1 and 0.48 mg/mL and 0.149 S-1, respectively. The enzymatic activity of the TAX1 produced by P. pastoris was about 2.4-4 times higher that directly isolated from T. atroviride, so engineered P. pastoris for xylanase production could be an ideal candidate for industrial enzyme production.

Corn stover is residual biomass that can be used for the production of fermentable sugars through enzymatic hydrolysis. However, a pretreatment step is required to enhance the enzymatic digestibility of biomass. Even though the alkaline hydrogen peroxide (AHP) method shows promise as an effective pretreatment for corn stover, a typical reaction time of 24 h is too long, and the amount of hydrogen peroxide required (~5% w/v) is too high. To address this problem, we developed a novel catalytic alkaline hydrogen peroxide (cAHP) method to shorten the pretreatment time and reduce hydrogen peroxide usage. This is the first time a metal catalyst, iron tetraamidomacrocyclic ligand (Fe-TAML) is combined with AHP to accelerate the oxidation of lignin using hydrogen peroxide under an alkaline condition. The reaction time can be shortened to 4.4 h from a typical reaction time of 24 h. With 5 ppm of Fe-TAML, the reducing sugar concentration is increased by 15% to 27.9 g/L, compared to the one without Fe-TAML. Next, the cAHP method is optimized by using response surface methodology (RSM). After the pretreatment of 10% corn stover in an alkaline solution (pH 10) with 8850 ppm H2O2 and 0.91 ppm catalyst for 4.4 h, the residual biomass can be recovered and hydrolyzed by using 10 U/mL at 12% solid loadings. After 24 h of hydrolysis, 36.2 g/L of reducing sugar is obtained, representing a 39.6% increase compared to traditional AHP using the same optimized condition.

Pyrolysis of lignocellulosic biomass is a renewable way to obtain densified energy and increase the raw material value in three different products: biochar, bio-oil, and gas. Agricultural waste is a promising biomass due to its high availability, especially in tropical countries, and lack of destination besides combustion. The bioenergy and biorefining potential were evaluated for four agricultural wastes: corn stover (CS), bean pods (BP), sugarcane bagasse (SCB), and pineapple crowns leaves (PCL) through an extensive physical and chemical characterization by proximate, ultimate and compositional analysis, high heating value (HHV), ash chemical composition, thermogravimetric analysis and analytical pyrolysis through Py–GC/MS. The results show that the biomasses present high HHV (16.1–19.3 MJ kg−1), low moisture and ash content, and high volatile content (77.8–82.8%), which are great characteristics for bio-oil production. According to Py–GC/MS results, the main pyrolysis products were phenols, furans, and C1–C4 oxygenated compounds. CS and BP presented a high phenolics yield (26.5%), which could be potentially recovered through biorefining. PCL showed the greatest energetic potential due to its highest HHV and could generate a high-quality fuel after deoxygenation routes. The bio-oil of these biomasses is a potential source of value-added chemicals after biorefining routes.

This study evaluates the influence of hydrothermal carbonization (HTC) or slow pyrolysis (SP) process conditions on the physicochemical properties of precursor biochars and activated carbon (AC). The AC is achieved through a direct or a two-step method with subsequent chemical activation using KOH. A theory is developed on the biochar propensity to be chemically activated based on the lignocellulosic structure composition. X-ray photoelectron spectroscopy elemental analysis shows that the O/C ratio decreases after chemical activation for HTC biochar but remains the same for SP biochar. X-ray powder diffraction indicates that the SP biochar and all ACs have broad amorphous carbon peaks, whereas corn stover and the HTC biochar have distinct cellulosic crystalline peaks. Vanillin adsorbent experiments were performed on various ACs with up to 98% reduction shown. The best adsorbent for vanillin was the AC produced directly from corn stover, followed by AC HTC and then AC SP.

Background Multiple analytical methods have been developed to determine the ratios of aromatic lignin units, particularly the syringyl/guaiacyl (S/G) ratio, of lignin biopolymers in plant cell walls. Chemical degradation methods such as thioacidolysis produce aromatic lignin units that are released from certain linkages and may induce chemical changes rendering it difficult to distinguish and determine the source of specific aromatic lignin units released, as is the case with nitrobenzene oxidation methodology. NMR methods provide powerful tools used to analyze cell walls for lignin composition and linkage information. Pyrolysis-mass spectrometry methods are also widely used, particularly as high-throughput methodologies. However, the different techniques used to analyze aromatic lignin unit ratios frequently yield different results within and across particular studies, making it difficult to interpret and compare results. This also makes it difficult to obtain meaningful insights relating these measurements to other characteristics of plant cell walls that may impact biomass sustainability and conversion metrics for the production of bio-derived fuels and chemicals. Results The authors compared the S/G lignin unit ratios obtained from thioacidolysis, pyrolysis-molecular beam mass spectrometry (py-MBMS), HSQC liquid-state NMR and solid-state (ss) NMR methodologies of pine, several genotypes of poplar, and corn stover biomass. An underutilized approach to deconvolute ssNMR spectra was implemented to derive S/G ratios. The S/G ratios obtained for the samples did not agree across the different methods, but trends were similar with the most agreement among the py-MBMS, HSQC NMR and deconvoluted ssNMR methods. The relationship between S/G, thioacidolysis yields, and linkage analysis determined by HSQC is also addressed. Conclusions This work demonstrates that different methods using chemical, thermal, and non-destructive NMR techniques to determine native lignin S/G ratios in plant cell walls may yield different results depending on species and linkage abundances. Spectral deconvolution can be applied to many hardwoods with lignin dominated by S and G units, but the results may not be reliable for some woody and grassy species of more diverse lignin composition. HSQC may be a better method for analyzing lignin in those species given the wealth of information provided on additional aromatic moieties and bond linkages. Additionally, trends or correlations in lignin characteristics such as S/G ratios and lignin linkages within the same species such as poplar may not necessarily exhibit the same trends or correlations made across different biomass types. Careful consideration is required when choosing a method to measure S/G ratios and the benefits and shortcomings of each method discussed here are summarized.

Background Hardsetting soils are considered problem soils due to its behavior of becoming hard and unbearable to cultivate not until rewetted. Few investigations were conducted in this kind of problem soil; hence, information about biomass yield and nutrient uptake is still elusive. This study investigated the impact of potentially hardsetting soil on the biomass yield and nutrient uptake of sweet corn under no-tillage cultivation system with varying fertilization treatments. Results The application of full NPK + 1 Mg ha−1 VC increased stover and grain yield by 26–106% and 11–135%, respectively. Approximately 64% and 112% of sweet corn stover and grain yield increased when treated with full NPK. Highly significant quadratic relationship (P P Conclusion Application of organic amendment in combination with inorganic fertilizer could be a sustainable production strategy on sweet corn production system in potentially hardsetting soil under no tillage through enhanced nutrient uptake and biomass accumulation.

BackgroundRetention of agricultural bio-mass residues without proper treatment could affect the subsequent plant growth. In the present investigation, the co-cultivation of genetically engineeredT. asperellumandB. amyloliquefacienshas been employed for multiple benefits including the enrichment of lignocellulose biodegradation, plant growth, defense potential and disease resistance.ResultsTheVel1gene predominantly regulates the secondary metabolites, sexual and asexual development as well as cellulases and polysaccharide hydrolases productions. Overexpression mutant of theTrichoderma asperellum Vel1locus (TA OE-Vel1) enhanced the activity of FPAase, CMCase, PNPCase, PNPGase, xylanase I, and xylanase II through the regulation of transcription regulating factors and the activation of cellulase and xylanase encoding genes. Further, these genes were induced upon co-cultivation withBacillus amyloliquefaciens(BA).The co-culture of TA OE-Vel1 + BA produced the best composition of enzymes and the highest biomass hydrolysis yield of 89.56 ± 0.61%. The co-culture of TA OE-Vel1 + BA increased the corn stover degradation by the secretion of cellulolytic enzymes and maintained the C/N ratio of the corn stover amended soil. Moreover, the TA OE-Vel1 + BA increased the maize plant growth, expression of defense gene and disease resistance againstFusarium verticillioidesandCohilohorus herostrophus.ConclusionThe co-cultivation of genetically engineered T.asperellumandB. amyloliquefacienscould be utilized as a profound and meaningful technique for the retention of agro residues and subsequent plant growth.

In recent years, the dissolution of lignocellulosic biomass using ionic liquids has attracted a lot of attention. Generally, the processes of valorisation of residual biomass do not extract cellulose. Among the lignocellulosic biomass, corn stover has a great interest because its high content in cellulose. For this reason, five ionic liquids have been designed and produced to dissolve the cellulose contained in corn stover, three tetra-alkyl-phosphonium based ILs and two imidazolium based ILs: tetra-butyl-phosphonium acetate [P4444][OAc]; tri-butyl-methyl-phosphonium acetate [P4441][OAc]; tetra-butyl-phosphonium 2-ethyl-hexanoate [P4444][EH]; 1-dodecyl-3-methyl-imidazolium bis (2,4,4-tri-methyl-pentyl) phosphinate [C12mim][(iC8)2PO2]; 1-decyl-3-methyl-imidazolium bis (2,4,4-tri-methyl-pentyl) phosphinate [C10mim][(iC8)2PO2]. The dissolution of cellulose was carried out under mild conditions (3 h and 80℃). Among the synthesised ionic liquids [P4444][EH] turned out to dissolve the greatest amount of cellulose (84 %), while imidazolium ionic liquids [C12mim][(iC8)2PO2] and [C10mim][(iC8)2PO2] dissolved 61.1 % and 44.0 %, respectively. On the other hand, these designed ILs have the ability to be easily recovered. As they are microemulsion-forming ionic liquids, the recycling of these ionic liquids was more straightforward (without the need of solvent evaporation). Furthermore, imidazolium ionic liquids were found to eliminate more ashes from the corn stover than tetra-alkyl-phosphonium ionic liquids.

The present study investigated the effect of organic nitrogen sources, soybean curd residue (SCR), and fish meal (FW) on the anaerobic digestion of corn stover for biomethane production. The bioreactors were seeded with the corn stover (corn cob and corn sheath), soybean curd residue (SCR), and fish waste (FW) at different combinations: (CC/SCR), (CC/FW), (CS/SCR) and (CS/FW), including CC and CS alone. The fermentation was for 31 days under mesophilic conditions. Characteristics of the substrates indicate that CC and CS are good carbon and energy sources, but low in nitrogen content. Conversely, SCR and FW are rich nitrogen sources, with low organic carbon content. There was a remarkable increase in biogas production in all treatments, except CC/SCR 75:25 and CC/SCR 85:15 in which inhibitory effect was observed. The highest percentage increase (138%) in biogas was recorded in CS/SCR 85:15 (2.86 dm3), and the least was CC/FW 75:25 with 1.49 dm3 (24.18% increase). Significant difference (P ≤ 0.05) in biogas yield was in the following: CC/SCR 50:50, CC/FW 50:50, CS/SCR 85:15, CS/FW 50:50, and CS/FW 75:25. The composition of the biogas revealed that the treatment improved biogas production as well as biomethane content, the highest being 69.44% in CS/SCR 85:15. Regression analysis of cumulative biogas yield as a function of time (t) in the different treatments that had a significant difference in biogas yield showed a good correlation between biogas yield (GY) and time (t). Improving the biodegradability of lignocellulosic wastes could lead to a boost in the development of anaerobic digestion and biogas production technology. To improve their biodegradability during anaerobic digestion, both pre-treatments and supplementation have vital roles to play.