Corncob Residue Research Articles

Valorization of residual lignin from corncob residues into thermosensitive lignin-based “molecular glues” for recycling cellulase

The cost of enzymolysis is a major bottleneck for the industrialisation of lignocellulosic enzymatic hydrolysis technology, and recycling cellulase can reduce this cost. Herein, a sulfobetaine prepolymer (CPS) with terminal chlorine was grafted onto enzymatic hydrolysis residual lignin (EHL) from corncob to construct thermosensitive lignin-based “molecular glues” (lignin-based sulfobetaine polymers, L-CPS) that were used to recover and recycle cellulase. L-CPS2 (1.0 g/L) was added to the corncob residue (CCR) enzymolysis system (50 °C, pH 4.5). After hydrolysis, L-CPS2 co-precipitated with cellulase through hydrophobic binding when cooling to 25 °C. This co-precipitation decreased the amount of cellulase by 40 %. In summary, a thermally responsive lignin-based molecular glue was constructed for green recycling of cellulase, providing a new approach to decreasing the cost of lignocellulosic enzymolysis and high value utilisation of industrial lignin.

Cellulosic Ethanol Production from High-Solids Corncob Residues by Simultaneous Saccharification and Fermentation on a Pilot Scale

Cellulosic Ethanol Production from High-Solids Corncob Residues by Simultaneous Saccharification and Fermentation on a Pilot Scale

Integrated production of xylose and docosahexaenoic acid from hemicellulose and cellulose in corncob

Exploring efficient and comprehensive utilization of agricultural waste to produce high value-added products has been global research hotspot. In this study, a novel process for integrated production of xylose and docosahexaenoic acid (DHA) from hemicellulose and cellulose in corncob was developed. Corncob was treated with dilute H2SO4 at 121 °C for 1 h and xylose was readily produced with a recovery yield of 79.35 %. The corncob residue was then subject to alkali pretreatment under optimized conditions of 0.1 g NaOH/g dry solid, 60 °C for 2 h, and the contents of cellulose, hemicellulose, and lignin in the resulting residue were 87.49 %, 7.58 % and 2.31 %, respectively. The cellulose in the residue was easily hydrolyzed by cellulase, yielding 74.87 g/L glucose with hydrolysis efficiency of 77.02 %. Remarkably, the corncob residue hydrolysate supported cell growth and DHA production in Schizochytrium sp. ATCC 20888 well, and the maximum biomass of 32.71 g/L and DHA yield of 4.63 g/L were obtained, with DHA percentage in total fatty acids of 36.89 %. This study demonstrates that the corncob residue generated during xylose production, rich in cellulose, can be effectively utilized for DHA production by Schizochytrium sp., offering a cost-effective and sustainable alternative to pure glucose.

Co-production of high-concentration fermentable sugar and lignin-based bio-adhesive from corncob residue via an enhanced enzymatic hydrolysis

Xylose plants (produce xylose from corncob through dilute acid treatment) generate a large amount of corncob residue (CCR), most of which are burned and lacked of valorization. Herein, to address this issue, CCR was directly used as starting material for high-solid loading enzymatic hydrolysis via a simple strategy by combining PFI homogenization (for sufficient mixing) with batch-feeding. A maximum glucose concentration of 187.1 g/L was achieved after the saccharification with a solid loading of 25 wt% and enzyme dosage of 10 FPU/g-CCR. Furthermore, the residue of enzymatic hydrolysis (REH) was directly used as a bio-adhesive for plywood production with both high dry (1.7 MPa) and wet (1.1 MPa) surface bonding strength (higher than the standard (0.7 MPa)), and the excellent adhesion was due to the interfacial crosslinking between the REH adhesive (containing lignin, free glucose, and nanosized fibers) and cell wall of woods. Compared with traditional reported adhesives, the REH bio-adhesive has advantages of formaldehyde-free, good moisture resistance, green process, relatively low cost and easy realization. This study presents a simple and effective strategy for better utilization of CCR, which also provides beneficial reference for the valorization of other kinds of lignocellulosic biomass.

Catalytic pyrolysis of corncob residues and pubescens over pristine and alkalis-treated HZSM-5

The catalytic pyrolysis of corncob residues and pubescens was carried out using HZSM-5 and alkalis-treated HZSM-5 as catalysts. HZSM-5 treated with different alkalis (TPAOH and a mixture of NaOH and Na2CO3) to get TPHZSM-5 and DHZSM-5. It was shown that the acid sites of the DHZSM-5 and TPHZSM-5 catalyst decreased compared to pristine HZSM-5. The hierarchical structures combining micro- and meso- porosity was formed in DHZSM-5, which was more conducive to promoting the formation of mono-phenols. However, the pore size of the catalyst decreased and the strength strong acid site increased with TPAOH treatment, which was beneficial for promoting C-O bond cleavage and generating more monocyclic aromatic hydrocarbons (MAHs). Under the same conditions, HZSM-5 was most beneficial for improving the yield of bio-oil (45.9 wt% of corncob residues and 52.0 wt% of pubescens). Analysis of the bio-oil showed that the catalytic pyrolysis of biomass over HZSM-5 achieved the highest PAHs yield (31.45 % from corncob residues and 18.38 % from pubescens), while TPHZSM-5 obtained the highest MAHs yield (5.92 % from corncob residues and 2.03 % from pubescens). However, DHZSM-5 catalyst appeared to have no significant effect on the increase of MAHs and PAHs yield, which may be attributed to its promotion of secondary polymerization of pyrolysis products. Additionally, the catalyst promoted the secondary cracking of pyrolysis vapor and reduced the average molecular weight (Mn) of the bio-oil. DHZSM-5 and TPHZSM-5 catalysts offered significant potential for the valorization of lignin, facilitating the production of value-added mono-phenolic compounds, MAHs, and high-quality fuels.

Exploring Corn Cob Gasification as a Low-Carbon Technology in the Corn Flour Industry in Mexico

In 2021, Mexico produced approximately 24.2 million tons of white corn, generating 3.6 million tons of corn cob residue. The final disposal of corn cob poses an environmental challenge in certain regions. This study examines the technical–economic feasibility and the greenhouse gas (GHG) mitigation potential of integrating a small-scale cogenerating gasifier fueled by corn cob into a nixtamalized corn flour manufacturing small and medium-sized enterprise (SME). This integration enables the generation of heat and electricity from the produced synthesis gas. Moreover, the process yields residual carbon, which can be used as biochar for soil restoration and removing atmospheric CO2. This option holds significance for the corn flour agroindustry in Mexico, as, in 2021, it consumed approximately 601.9 GWh of electrical energy and 938,279 GJ of thermal energy from LP Gas in its manufacturing processes to produce 2.6 million tons of nixtamalized white corn flour. These processes contributed to a total emission of 410,232 tons of CO2 into the atmosphere. The findings of this study demonstrate a cumulative reduction of 51.7% in CO2 emissions, resulting in economic benefits of USD 85,401 in 2017 for a case study SME that annually produces 1039 tons of corn flour. This study reveals the integration of a gasifier–cogenerator system fueled by corn cob as an economically viable low-carbon technology in the corn flour manufacturing industry.

A comparative study on kinetic and thermodynamic studies for pyrolysis of corn-cob with and without aluminium oxides catalyst using thermogravimetric analysis

ABSTRACT The utilization of corncob residues in pyrolysis offers a promising source for both renewable energy and chemical production. In this study, corncob was decomposed in the presence of aluminum oxide nanoparticles (Al2O3 NPs) catalyst using a fixed bed reactor under an inert atmosphere. Pyrolysis of corncob was carried out in the presence of Al2O3 NPs at different heating rates i.e. 5, 10, 15 and 20°C/min in an oxygen-free atmosphere using TGA technique. Kinetic and thermodynamic studies were performed using the best fit models including Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS) and Friedman methods. The average activation energies for Friedman, OFW, KAS were 177.3, 162.9 and 167.8 kJ/mol, respectively for pure corncob and 111.0, 102.5 and 118.06 kJ/mol, respectively for Al2O3-corncob sample. Activation energy was found to be the lowest in the OFW model. Results showed that the presence of Al2O3 NPs catalyst not only reduced pyrolysis temperature and activation energy but also improved the quality of bio-oil.

Investigation on hydrothermal-pyrolysis process to eliminate S-pollution from corncob residue utilization: Experiment and life cycle assessment

Corncob residue (CR) is characterized by high S and moisture content, which results in large SOx emissions in the thermal process (incineration/pyrolysis). This study investigated a new hydrothermal-pyrolysis method (HT-PY) to obtain high-quality products (phenol-rich and low moisture content bio-oil, S-free char). Compared with S content of CR, the S content of hydrochar obtained from 300 ℃-HT decreased 63.33 %. After pyrolysis, the S and volatile-sulfur (VS) content of char obtained from 300HT-550PY decreased 84.45 % and 95.24 %, only 0.14 % and 0.01 %. Compared with direct pyrolysis of CR, Hydrothermal pre-treatment improved the decomposition of organic-S in solid phase and eliminate the S-emissions of gas phase. Basing on the experimental data and process simulation, life cycle assessment, and economic cost analysis of CR-HT-PY were also provided benefits. The steam of the hydrothermal unit recovered to the heat supply of furfural production (30796.21 MJ). And the HT-PY system exhibited the lowest GWP and AP environmental impact, SO2 emissions of CR-HT-PY was merely emitted during the hydrothermal process (0.32 kg/ton CR), decreased 98.03 % (15.92 kg SO2/ton CR) compared with direct pyrolysis. The carbon utilization efficiency was also increased by 41.37 % due to higher-quality products. In addition, due to the high value of S-free char, the total economic efficiency of CR-HT-PY was more than twice that of other systems.

Production of cello-oligosaccharides from corncob residue by degradation-synthesis reactions.

The cellulose-rich corncob residue (CCR) is an abundant and renewable agricultural biomass that has been under-exploited. In this study, two strategies were compared for their ability to transform CCR into cello-oligosaccharides (COS). The first strategy employed the use of endo-glucanases. Although selected endo-glucanases from GH9, GH12, GH45, and GH131 could release COS with degrees of polymerization from 2 to 4, the degrading efficiency was low. For the second strategy, first, CCR was efficiently depolymerized to glucose and cellobiose using the cellulase from Trichoderma reesei. Then, using these simple sugars and sucrose as the starting materials, phosphorylases from different microorganisms were combined to generate COS to a level up to 100.3g/L with different patterns and degrees of polymerization. Using tomato as a model plant, the representative COS obtained from BaSP (a sucrose phosphorylase from Bifidobacterium adolescens), CuCbP (a cellobiose phosphorylase from Cellulomonas uda), and CcCdP (a cellodextrin phosphorylase from Clostridium cellulosi) were shown to be able to promote plant growth. The current study pointed to an approach to make use of CCR for production of the value-added COS. KEY POINTS: • Sequential use of cellulase and phosphorylases effectively generated cello-oligosaccharides from corncob residue. • Cello-oligosaccharides patterns varied in accordance to cellobiose/cellodextrin phosphorylases. • Spraying cello-oligosaccharides promoted tomato growth.

Custom-designed polyphenol lignin for the enhancement of poly(vinyl alcohol)-based wood adhesive

Adhesives are used extensively in the wood industry. As resource and environmental issues become increasingly severe, the development of green and sustainable biomass-based adhesives has attracted increasing attention. In this work, a green wood adhesive is developed from poly(vinyl alcohol) and lignin with molecular designs of lignin extending beyond those in nature. The lignin undergoes extraction from corncob residue, aldehydration, and phenolisation (phenol, resorcinol, and catechol) to significantly increase the phenolic hydroxyl groups (over 7.92 mmol/g), which has the effect of enhancing the hydrogen bonding force between the adhesive and the wood, thereby greatly improving adhesive performance. Compared with pure PVA, polyphenol lignin-containing PVA showed improved adhesion strength and hydrophobicity. PVA/resorcinol-lignin has the significantly improved wood lap shear strength (6.27 MPa, 77.6 % improvement) and hydrophobicity (almost 100 % increase in wet shear strength). This research not only provides a green and high-performance alternative raw material for wood adhesives but also broadens the path for large-scale application of biomass.

Biomass@MOF nanohybrid materials for competitive drug adsorption: analysis by conventional macroscopic models and statistical physical models

This study discloses the design of nanohybrid Biomass@MOF resulting from the functionalization of a hydrochar (HC) through hydrothermal treatment (HT) of corn cob residues and MIL-53(Al).

Simultaneous saccharification and fermentation residues as potential sources of phenolics by fast pyrolysis (Py-GC/MS) and alkaline hydrolysis

Unlike 1 G bioethanol, the success of 2 G technology faces difficulties. The economic difficulties of 2 G bioethanol can be solved with an additional income in by-products, mainly from lignin. The present study investigated the generation of phenolics via fast pyrolysis and alkaline hydrolysis using residues from saccharification and simultaneous fermentation (SSF) as substrate. The SSF residues were obtained from schemes with green coconut fiber (without chemical pretreatment) and corn cob (with previous acid pretreatment). Chemical composition, FTIR, and XRD analyses confirmed that the processing undergone by SSF residues altered the lignocellulose structure. Due to extractives removal and lignin increase, the fast pyrolysis experiments with SSF residues favored the generation of phenolics over C1-C4 products. Phenol was the main product in the pyrolysis of untreated green coconut fiber (14.64%) and SSF residue (13.51%), while the 2-methoxy-4-vinylphenol content in the bio-oil was doubled with the SSF corn cob residue (from 12.87% to 27.01%). SSF corn cob residue showed a high yield of hydroxynamic acids after alkaline hydrolysis with sodium hydroxide. The p-coumaric acid yield reached 4337 mg/100 g in experiments at 60 °C. Based on the results, the conversion of SSF residues appears as an alternative to obtain commercially appealing phenolics and may be attractive for 2 G bioethanol technology.

Corncob-Derived Sulfonated Magnetic Solid Catalyst Synthesis as Heterogeneous Catalyst in The Esterification of Waste Cooking Oil and Bibliometric Analysis

A corncob-derived magnetic solid acid catalyst was synthesized through the sulfonation method and an impregnation process, respectively. In the sulfonation process, the concentrated H2SO4 was utilized as an activation agent to obtain acidic properties. The solution of ferric sulphate-ferrous sulphate was utilized for impregnation to generate the magnetic behaviour of the material. The prepared magnetic acid solid catalyst had a high saturation magnetisation value of 16.48 emu/g and a total acidity of 1.43 mmol/g. The performance of the catalyst was evaluated in the esterification reaction of waste cooking oil. The best result presented 86.12% FFA conversion under reaction conditions of 5% catalyst loading and a 1:15 oil-to-methanol molar ratio at 60oC for 4 h. The catalyst was separated magnetically from the reaction solution and exhibited a good reusability with 61% remaining active after 5 consecutive cycles of reaction. This study resulted in a promising method to obtain magnetic-sulfonated carbon-based catalyst from corncob residue, and it is economical potentially and environmentally friendly for the esterification of low-quality feedstock for biodiesel production.

Preparation and characterization of corn cob cellulose acetate for potential industrial applications

Background: Locally generated biopolymers are amenable to further processing to widen their industrial applications. The study was aimed at generating low-cost cellulose acetate from corn cob residue and its characterizations for potential applications in biopolymer industries. Methods: Cellulose was extracted from the corn cob residue using the sodium hydroxide method. Acetylation of the cellulose to obtain corn cob cellulose acetate was carried out by adding appropriate quantities of a glacial acetic and acetylating mixture of acetic anhydride and sulphuric acid. The corn cob native cellulose and corn cob cellulose acetate were characterized using scanning electron microscopy (SEM) to examine their morphology, Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD) for structural elucidation while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to investigate their thermal properties. Results: - Two corn cellulose acetate samples with degree of substitutions 1.87 and 2.65 for samples CDA and CA respectively were obtained. They had improved solubilities in some organic solvents compared to the corn cob cellulose. The SEM examination showed the surface of the corn cob native cellulose (NC) was smooth and had a regular bundle-like structure while acetylation destroyed the original cellulose structure. Cellulose acetate samples showed a cluster-like structure with different sizes and a rough flake-like surface. FTIR and XRD studies showed that acetyl groups substituted cellulose hydroxyl groups. While FTIR study showed that the cellulose acetates had sharp bands between 1728 cm-1 to 1733 cm-1 and around 1368 cm-1 wavenumber unlike the corn cob cellulose sample, the data generated from XRD study indicated that acetylation of the corn cob cellulose led to 47% and 77% decrease in the crystallinity of CDA and CA samples respectively. The thermal analysis data from DSC and TGA studies confirmed that the acetylation improved the corn cob cellulose's thermal stability as indicated by the degradation of cellulose acetate samples at higher temperatures. Conclusion: The study concluded that low-cost cellulose acetate generated from corn cob residue could be potentially employed as a renewable, biodegradable, biocompatible polymer for industrial applications.

Using Dielectric Constant Measurement to Monitor Ethanol Fermentation and Anaerobic Co-Digestion of Lignocellulosic Biomass

Our study aimed to investigate the applicability of dielectric measurements across three key stages of plant-based biomass utilization: enzymatic hydrolysis of native and microwave pre-processed corn-cob residues, ethanol fermentation of the hydrolysates, and anaerobic co-digestion with meat-industry wastewater sludge. Our major findings reveal that microwave pre-treatment not only accelerates enzymatic hydrolysis but also improves sugar yield. A strong linear correlation (r = 0.987–0.979; R2 = 0.974–0.978) was observed between the dielectric constant and sugar concentrations, offering a reliable monitoring mechanism. During ethanol fermentation, microwave pre-treated samples resulted in higher yields; however, the overall bioconversion efficiency was lower. Dielectric measurements also exhibited a strong linear correlation (r = 0.989–0.997; R2 = 0.979–0.993) with ethanol concentration. Finally, anaerobic co-digestion could be effectively monitored through the measurement of the dielectric constants (r = 0.981–0.996; R2 = 0.963–0.993), with microwave-treated samples showing higher biogas yields. These results demonstrate that dielectric measurements provide a promising alternative for monitoring and controlling biomass utilization processes.

Efficient production of xylobiose and xylotriose from corncob by mixed acids and xylanase hydrolysis

Propionic acid (PA) hydrolysis offers a potential pathway for industrial xylooligosaccharide (XOS) production owing to efficiency and simplicity of the process. However, the cost of XOS production needs to be reduced as PA is expensive. This work proposed a strategy of mixed acids hydrolysis, replacing 20% of PA with formic acid (FA), and combined with xylanase hydrolysis to reduce production costs and increase the production of XOS from corncob. The hydrolysis of corncob using mixed FA and PA in a mass ratio of 2:8 produced 61.8% XOS. Xylanase hydrolysis of corncob residue improved XOS yield to 73.1%. Among them, the X2 + X3 yield was as high as 50.6%. Economic evaluation showed that the combined process reduced the XOS production cost by 10.8% compared to PA hydrolysis. The strategy of using FA instead of 20% PA for hydrolysis and enzymatic hydrolysis, with high XOS and monosaccharide yields from corncob, has potential industrial promise.

Isolation of lignocellulosic components from corncob residue through industrially viable cleaner processes and their techno-economic analysis

Isolation of lignocellulosic components from corncob residue through industrially viable cleaner processes and their techno-economic analysis

Synthesis of bifunctional thermal response promoters for improved high-solids enzymatic hydrolysis of corncob residues

The enzymatic hydrolysis cost of lignocellulose can be reduced by improving enzymatic hydrolysis and recycling cellulase by adding additives. A series of copolymers P(SSS-co-SPE) (PSSPs) were synthesized using sodium p-styrene sulfonate (SSS) and sulfobetaine (SPE) as monomers. PSSP exhibited upper critical solution temperature response. PSSP with high molar ratio of SSS displayed more significant improved hydrolysis performance. When 10.0 g/L PSSP5 was added to the hydrolysis system of corncob residues, and substrate enzymatic digestibility at 72 h (SED@72 h) increased by 1.4 times. PSSP with high molecular weight and moderate molar ratio of SSS, had significant temperature response, enhanced hydrolysis, and recovering cellulase properties. For high-solids hydrolysis of corncob residues, SED@48 h increased by 1.2 times with adding 4.0 g/L of PSSP3. Meanwhile, 50% of cellulase amount was saved at the room temperature. This work provides a new idea for reducing the hydrolysis cost of lignocellulose-based sugar platform technology.

Complete conversion of xylose-extracted corncob residues to bioplastic in a green and low carbon footprint way

Lignocellulosic biomass is a favorable resource for the production of plastics, which are traditionally based on fossil fuels. However, the production of bioplastics from woody biomass usually requires the fractionation of the main components, namely cellulose, hemicellulose, and lignin, which increases the economic cost and environmental impact, and most bioplastics have poor water stability and mechanical properties, which seriously hinder the practical application. Herein, a simple method for the production of bioplastics was developed that avoids the fractionation of lignin from cellulose and produces bioplastics with good properties. Specifically, corn cob residues after xylose extraction, as a by-product of the existing xylose industry, were dissolved in a metal salt solution (ZnCl2/CaCl2 system) to produce high-performance bioplastics. The resulting lignocellulosic bioplastic is biodegradable, recyclable, water stable (No decomposition within two months), and most importantly, offers exceptional mechanical properties (136 MPa) and lower environmental impact compared to conventional plastics. Overall, this environmentally friendly lignocellulosic bioplastic demonstrated in our study could be a promising substitute for petrochemical plastics.

Enhanced Enzymatic Hydrolysis of High-Solids Content Corncobs by a Lytic Polysaccharide Monooxygenase from Podospora anserina S Mat+ for Valuable Monosaccharides

Lytic polysaccharide monooxygenase (LPMO) has been found to enhance cellulase activity and promote efficient utilization of corncob cellulose. To this end, a novel LPMO from Podospora anserina S mat+ (PaLPMO) through in silico screening was heterologously expressed in Escherichia coli BL21(DE3) and its biochemical properties were investigated. To reduce production costs, chaperones and site-directed mutagenesis were employed to enhance the protein’s solubility, yielding an 8% increase. Through single-factor experiments, the optimal hydrolysis condition for the highest glucose yield of 129.8 g/L was identified as 25% high-solids content of corncob at 60 °C and pH 5.5 using a PaLPMO-to-cellulase ratio of 1:3 (total protein concentration of 12 mg/g) and with the addition of 0.5 mmol/L Mn2+. This result represented a 24% improvement compared to cellulase alone and a 33% reduction in commercial cellulase usage with the same degree of hydrolysis. The hydrolysis products of high-solids content corncob degradation were further used to produce valuable d-allulose through glucose isomerase and d-allulose 3-epimerase catalysis in a ratio of 2:1, with a yield of 56.22 g/L fructose and 20.6 g/L d-allulose. The PaLPMO and cellulase complex significantly improved the degradation efficiency of corncob residue and reduced cellulase usage in lowering the production cost. These findings contribute to developing comprehensive corncob utilization and pave the way for sustainable and efficient energy and resource utilization.