Raw Corncob Research Articles

Rewiring metabolic flux to simultaneously improve malate production and eliminate by-product succinate accumulation by Myceliophthora thermophila.

Although a high titre of malic acid is achieved by filamentous fungi, by-product succinic acid accumulation leads to a low yield of malic acid and is unfavourable for downstream processing. Herein, we conducted a series of metabolic rewiring strategies in a previously constructed Myceliophthora thermophila to successfully improve malate production and abolish succinic acid accumulation. First, a pyruvate carboxylase CgPYC variant with increased activity was obtained using a high-throughput system and introduced to improve malic acid synthesis. Subsequently, shifting metabolic flux to malate synthesis from mitochondrial metabolism by deleing mitochondrial carriers of pyruvate and malate, led to a 53.7% reduction in succinic acid accumulation. The acceleration of importing cytosolic succinic acid into the mitochondria for consumption further decreased succinic acid formation by 53.3%, to 2.12 g/L. Finally, the importer of succinic acid was discovered and used to eliminate by-product accumulation. In total, malic acid production was increased by 26.5%, relative to the start strain JG424, to 85.23 g/L and 89.02 g/L on glucose and Avicel, respectively, in the flasks. In a 5-L fermenter, the titre of malic acid reached 182.7 g/L using glucose and 115.8 g/L using raw corncob, without any by-product accumulation. This study would accelerate the industrial production of biobased malic acid from renewable plant biomass.

Adsorptive Removal of Lead (II) Pollutants from Wastewater Using Corncob-Activated Carbon

he level of contamination in industrial wastewater has been a serious environmental challenge of our time. Various researchers have reported that the adsorption process using different adsorbents is a promising technique for treating heavy metal-contaminated wastewater. This study investigated the adsorptive removal of lead (II) from wastewater using corncob-activated carbon. Activated carbon was synthesized from a raw corncob. The synthesized activated carbon was applied as a sorbent in batch lead (II) adsorption in an aqueous lead (II) solution. Scanning electron microscopy, Fourier transformed infrared (FTIR), and Brunauer–Emmett–Teller (BET) theory characterized the synthesized activated carbon. A batch adsorption study investigated the effects of dosage, contact time, and the initial concentration of lead (II) on the sorption of Pb2+ on the synthesized activated carbon. The highest removal of lead recorded was 95 % at an adsorbent dosage of 2.5 g/L in 2 h. The highest adsorption capacity was 16.46 mg/g at the same conditions. The results showed that percentage removal increased with dosage and contact time but decreased with the initial metal ion concentration. Adsorption kinetics were best described with the pseudo-second-order kinetics, while the Langmuir isotherm model best fitted equilibrium adsorption in the study. The FTIR results showed the presence of several functional groups like carboxyl, hydroxyl, and amino, indicating good interaction with lead metal ions. The BET characterization revealed the activated corncob’s specific surface area and pore volume to be 249 m2/g and 0.164 cm3/g. This work shows that activated carbon can be synthesized from agricultural waste such as corncob and be used as an effective adsorbent for heavy metal removal, such as lead, from wastewater.

Novel Strain of Paenibacillus phyllosphaerae CS-148 for the Direct Hydrolysis of Raw Starch into Glucose: Isolation and Fermentation Optimization.

The conventional process for converting starch to glucose is energy-intensive. To lower the cost of this process, a novel strain of Paenibacillus phyllosphaerae CS-148 was isolated and identified, which could directly hydrolyze raw starch into glucose and accumulate glucose in the fermentation broth. The effects of different organic and inorganic nitrogen sources, the culture temperature, the initial pH, and the agitation speed on the yield of glucose were optimized through the one-factor-at-a-time method. Nine factors were screened by Plackett-Burman design, and three factors (raw corncob starch, yeast extract and (NH4)2SO4) had significant effects on glucose yield. Three significant factors were further optimized using Box-Behnken design. Under the optimized fermentation conditions (raw corncob starch 40.4 g/L, yeast extract 4.27 g/L, (NH4)2SO4 4.39 g/L, KH2PO4 2 g/L, MgSO4`7H2O 2 g/L, FeSO4`7H2O 0.02 g/L, NaCl 2 g/L, KCl 0.5 g/L, inoculums volume 4%, temperature 35 °C, agitation rate 150 rpm, and initial pH 7.0), the maximum glucose yield reached 17.32 ± 0.46 g/L, which is 1.33-fold compared to that by initial fermentation conditions. The maximum conversion rate and glucose productivity were 0.43 ± 0.01 g glucose/g raw corn starch and 0.22 ± 0.01 g/(L·h), respectively. These results implied that P. phyllosphaerae CS-148 could be used in the food industry or fermentation industry at a low cost.

Eco-friendly and rapid one-step fermentable sugar production from raw lignocellulosic biomass using enzyme mimicking nanomaterials: A novel cost-effective approach to biofuel production

Cerium-doped iron oxide nanoparticles (CeFe3O4-NPs) possessing exceptional laccase and cellulase/hemicellulase mimicking properties were exploited for simultaneous pretreatment (i.e. delignification) and saccharification (SPS) of raw corn cob (CC) biomass. Here, we developed an eco-friendly single step SPS strategy for conversion of raw CC biomass into C6 and C5 sugars using CeFe3O4-NPs with in-houseproduced cellulase andhemicellulaseenzymes which generated maximum glucose (20.3 ± 1.01 g/L) and xylose (22.0 ± 2.22 g/L) within 24 h of hydrolysis at 55 °C and further 21.7 g/L of bioethanol was produced by Saccharomyces cerevisiae. These results clearly elucidated the role of CeFe3O4-NPs as lignocellulose degrading laccase and cellulase/hemicellulase enzymes. Remarkably, the presence of CeFe3O4-NPs has triggered xylose utilization in S. cerevisiae which is completely a new finding. This study can provide new insights towards the probable role of CeFe3O4-NPs in the up-regulation of significant genes responsible for xylose utilization which is a noteworthy finding in the field of ‘biomass to biofuel’ conversion.

Denitrification in bioretention systems based on corncob biochar produced at low pyrolysis temperature: The efficacy and the mechanisms

In this study, the performance of corncob biochar (CCB) produced at 250 °C, a relatively low temperature for biochar production, on nitrate removal was investigated under dynamic flow conditions based on bench column and scale-up bioretention device experiments. CCB could continuously release sufficient soluble organic compounds for denitrification. In the column experiment, the highest denitrification rate of 130.3 mg·N/(L·d) was observed at HRT of 8 h, which was much higher than the raw corncob. At the HRT of 8 h, the nitrate removal efficiency could maintain 100 % with the influent NO3–-N concentration not higher than 30 mg/L. The presence of CCB at a mass content of 5 % in the scale-up bioretention device could significantly improve the nitrate removal performance and there was barely accumulation of nitrite. The universal molecular characterization of the DOM based on FT-ICR MS showed that the DOM from CCB contained less proteins and more hydrophobic aromatic compounds than from the raw corncob, which was responsible for the prolonged and steady release of TOC and thus the better performance of denitrification for CCB. These results showed the potential of corncob biochar produced at low temperatures to apply to the bioretention facilities for urban stormwater management.

Production and Characterization of Green Biosorbent Based on Modified Corn Cob Decorated Magnetite Nanoparticles

In most developing countries, particularly in the countries of sub-Saharan Africa, corn cobs are considered as waste polluting the environment during the harvest period of this cereal. In order to valorize this agricultural waste, high-performance, inexpensive and low-energy consumption magnetic bioadsorbents were prepared from corn cobs. The chemically activated raw corn cob was magnetized by coating the surface with magnetite nanoparticles. The prepared biosorbents were characterized by FT-IR, XRD, FE-SEM associated with EDX, HR-TEM, TG analysis, BET surface area analysis and XPS. The maximum specific surface area of 35.22 m2/g was reached. An attempt to use of these magnetic biosorbents for the removal of heavy metal like Cr(VI) from aqueous solution was envisaged.

Parametric optimization of the production of cellulose nanocrystals (CNCs) from South African corncobs via an empirical modelling approach

In this study, cellulose nanocrystals (CNCs) were obtained from South African corncobs using an acid hydrolysis process. The delignification of corncobs was carried out by using alkali and bleaching pretreatment. Furthermore, the Box-Behnken Design (BBD) was used as a design of experiment (DOE) for statistical experimentations that will result in logical data to develop a model that explains the effect of variables on the response (CNCs yield). The effects (main and interactive) of the treatment variables (time, temperature, and acid concentration) were investigated via the response methodology approach and the obtained model was used in optimizing the CNCs yield. Surface morphology, surface chemistry, and the crystallinity of the synthesized CNC were checked using scanning electron microscopy (SEM), a Fourier Transform Infra-red spectroscopy (FTIR), and an X-ray diffraction (XRD) analysis, respectively. The SEM image of the raw corncobs revealed a smooth and compact surface morphology. Results also revealed that CNCs have higher crystallinity (79.11%) than South African waste corncobs (57.67%). An optimum yield of 80.53% CNCs was obtained at a temperature of 30.18 °C, 30.13 min reaction time, and 46 wt% sulfuric acid concentration. These optimized conditions have been validated to confirm the precision. Hence, the synthesized CNCs may be suitable as filler in membranes for different applications.

Green hydrogen production through consolidated bioprocessing of lignocellulosic biomass using nanobiotechnology approach

The main objective of this study was to develop a sustainable process for hydrogen production by implementing nanotechnology in combination with consolidated bioprocessing (CBP) approach from lignocellulosic biomass (LCB). Peroxidase mimicking CeFe3O4 nanoparticles (NPs, 4.0 g/L) were applied for degradation of lignin from raw corn cob (CC) biomass for generation of cellulose-hemicellulose fractions amenable towards Clostridium cellulovorans during fermentation process. NP-treated biomass exhibited 43.26 % lignin removal from raw CC which was further employed for hydrogen fermentation by C. cellulovorans through CBP method. The strain yielded maximum 78.45 mL of cumulative hydrogen with hydrogen production rate of 1.55 mL/h using NP-treated CC. To the best of our knowledge, this is the first study on enhanced hydrogen production using NP-treated CC biomass in single pot fermentation which can prove to be a simpler, easier, and more economical process.

Photodegradation of Reactive Blue 4 Using Suspension of Anatase-Titanium Dioxide and Corn Cob

Textile dyeing often employs reactive dyes. The dye wastewater contains hazardous materials and is toxic to humans and the environment. Photodegradation using a semiconductor photocatalyst is a promising alternative approach for water purification and wastewater treatment. However, the photocatalyst’s low adsorption ability is a problem in the photocatalysis process. To compensate for this shortcoming, photocatalyst content must be combined with an adsorbent. Raw corn cob and titanium dioxide (TiO2) were used in this photocatalysis. Due to a synergistic impact, raw corn cob’s ability to adsorb and titanium dioxide’s ability to photodegrade organic pollutants from water bodies is expected to boost the removal performance. The degradation of Reactive Blue 4 (RB4) as a targeted dye was carried out in this research using a suspended mixture of commercial anatase TiO2 and raw corn cob under UV light. The effect of initial pH solution, initial dye concentration and contact time, TiO2-corn cob dosages, and the influence of other pollutants were investigated as factors influencing photodegradation-adsorption of RB4. The high removal rate of RB4 was obtained at a low pH of 2 and RB4 concentration of 40 ppm. The increased dose of TiO2-corn cob improved the RB4 dye removal performance. In conclusion, combining photodegradation and adsorption systems as a hybrid treatment method resulted in a synergistic increase in the efficiency of RB4 removal.

Adsorption of anionic dyes from textile wastewater utilizing raw corncob

Toxic dyes are irrefutable effluent components of textile wastewater, so they have become a major economic and health concern. With the purpose of efficient removal of textile dyes, multiple nature-inspired adsorbents have been applied. Herein, raw corncob is proposed as a novel highly efficient, low-price, and abundantly attainable adsorbent with the potential for uptake of methyl red and methyl orange. Multiple experiments were carried out to optimize parameters including pH, primary concentration, adsorbent dosage, temperature, and contact time. The adsorption was raised with the mounting of the contact time and it was alleviated with the addition of initial concentration. The foremost uptake of dye was apperceived at an acidic medium pH 4 for methyl red and pH 1 for methyl orange. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were employed to characterize the surfaces of corncobs. The well-fitted Langmuir and Freundlich models (methyl red: R2 = 0.9956 and methyl orange: R2 = 0.9883) confirmed the homogeneous monolayer adsorption process on the raw corncob surface. The obtained results disclose that corncob is an effectual biosorbent for eliminating anionic dyes without the necessity for any prior modifications.

Pretreatment of corncob with green deep eutectic solvent to enhance cellulose accessibility for energy and fuel applications

Fossil fuels are the primary source of energy for a long period in spite of excessive environmental hazards, such as greenhouse gas emissions. Production of energy and fuel from lignocellulosic biomass has been the goal of the study in pursuit of renewable alternatives to fossil materials. Corncob is common agricultural biomass waste found in many countries. It can be utilized to produce bioenergy, but the conversion efficiency is limited. Pretreatment may be applied to improve the efficiency of corncob conversion; for example, by the fractionation of lignocellulosic biomass. Choline chloride (ChCl) and glycerol are considered as synthetic deep eutectic solvents (DESs), also known as green solvents. DESs are expected to fractionate hemicellulose and lignin from raw biomass, and the accessibility of cellulose may be enhanced. In this work, pretreatment of corncob with DES prepared from ChCl and glycerol was investigated at varying reaction temperatures (60–150 °C), residence times (6–15 h), and ChCl-to-glycerol molar ratios (1:0.5-4). The results showed that hemicellulose and lignin were effectively extracted from the raw corncob, and therefore, cellulose content in the remaining solid residue, known as cellulose-rich material (CRM), can be improved by least 140%. The reaction temperature, residence time, and presence of ChCl in the DES influenced the pretreatment of corncob significantly. Increases in reaction temperature and residence time led to a higher cellulose content in CRMs and an increased extraction of hemicellulose and lignin from the raw corncob. Without the ChCl in DES, the cellulose content in CRMs and the extraction of hemicellulose and lignin from the sample were decreased markedly. The optimal condition at 150 °C, 12-h residence time, and 1:4 ChCl-to-glycerol molar ratio could be used to improve the cellulose content of CRMs from the raw corncob by more than 150%. The CRM with improved lignocellulosic properties can be used as a feedstock in further bioenergy/fuel application.

The oxalic acid-assisted fast pyrolysis of biomass for the sustainable production of furfural

Pyrolysis is a promising thermal conversion technique of biomass to tackle the energy crisis and environmental pollution. Furfural (FF) is an important pyrolysis product from biomass-based materials and a crucial platform compound for energy and fuels. In the present study, we developed a new and green approach to selectively produce FF through the oxalic acid-assisted fast pyrolysis (OAFP) of corncob (CC). The FF yield was up to 16.5 wt% (based on raw CC) through the fast pyrolysis of the solid mixture of CC and OA with a ratio of 1:4 (CC/OA) at 400 °C during the micro-pyrolysis coupled with online-detection experiments. The corresponding FF selectivity was 56.5% (based on raw CC). Under similar experimental parameters, a yield of 10.0 wt% (based on raw CC) was achieved with a lab-scale setup. Experiment and density functional theory (DFT) calculation results suggested that OA played a catalyst-like role in the selective formation of FF from hemicellulose (mainly xylose units) of CC and meanwhile decomposed during the pyrolysis process. The formic acid (FA) decomposed from OA had a similar but lighter effect than OA. With the assistance of OA, the energy barriers of the FF formation reactions decrease dramatically and the competitiveness of the pathways is also altered, which contributes a lot to the FF selective generation. FF is mainly generated in a chain propagation pattern from the acyclic reducing end and unsaturated (C4C5 bond) non-reducing end of the xylan chain.

Identification and Characterization of a Novel Endo-β-1,4-Xylanase from Streptomyces sp. T7 and Its Application in Xylo-Oligosaccharide Production.

A xylanase-producing strain, identified as Streptomyces sp. T7, was isolated from soil by our lab. The endo-β-1,4-xylanase (xynST7) gene was found in the genome sequence of strain T7, which was cloned and expressed in Escherichia coli. XynST7 belonged to the glycoside hydrolase family 10, with a molecular mass of approximately 47 kDa. The optimum pH and temperature of XynST7 were pH 6.0 and 60 °C, respectively, and it showed wide pH and temperature adaptability and stability, retaining more than half of its enzyme activity between pH 5.0 and 11.0 below 80 °C. XynST7 showed only endo-β-1,4-xylanase activity without cellulase- or β-xylosidase activity, and it showed maximal hydrolysis for corncob xylan in all the test substrates. Then, XynST7 was used for the production of xylo-oligosaccharides (XOSs) by hydrolyzing xylan extracted from raw corncobs. The maximum yield of the XOS was 8.61 ± 0.13 mg/mL using 15 U/mL of XynST7 and 1.5% corncob xylan after 10 h of incubation at 60 °C. The resulting hydrolysate products mainly consisted of xylobiose and xylotriose. These data indicated that XynST7 might by a promising tool for various industrial applications.

Utilization of corncob as adsorbent to remove oil and grease from produced water

The hazardous composition of produced water (PW) places it as a dangerous contamination agent, which must be treated to meet environmental and operational requirements before disposal, reuse, or reinjection. The current work evaluated an adsorption treatment using raw and pretreated corncob samples to remove total oil and grease (TOG) from PW. The influence of adsorbent dosage (1.0, 2.5, and 5.0 g), particle size (0.5, 1.0, and 2.0 mm), and contact time (60, 120, and 240 min) were tested in a batch system, showing that the lowest oil concentration was achieved with the smallest particle size (0.5 mm) and highest contact time (240 min) and adsorbent dosage (5.0 g). Using a 20 cm secondary partition in the fixed-bed column system was more efficient for TOG removal than a 10 cm one: the raw corncob removed 85.23% of TOG against 17.41% pretreated biomass. Comparative studies showed that the adsorption performance of untreated corncob was superior to that observed for walnut shells (69%), a widely used commercial absorbent. Results indicated corncob’s environmental and economic potential as a natural and cost-effective adsorbent.

Improving the Combustion Properties of Corncob Biomass via Torrefaction for Solid Fuel Applications

The overdependence on fossils as the primary energy source has led to climate change, global warming, and the emission of greenhouse gas. As a result, the United Nations, while setting the goals for the year 2030, has made the provision of a green environment and energy one of the top priorities. In this study, the suitability of corncob for green energy production was investigated. The improvement of corncob’s thermal and combustion properties via the torrefaction process was considered for solid fuel applications. The raw corncob was collected, sorted, and dried for seven days before being used for the torrefaction experiment. Different torrefaction temperatures (200, 240, and 260 °C) and residence times (20, 40, 60 min) were studied. There was no particle reduction—samples were torrefied as collected (whole corncob). The results show that torrefaction temperature and residence time affect the torrefaction products yields along with their properties. Thermal and combustion properties were improved with an increase in torrefaction temperature and residence time. The higher heating value and energy density of the torrefied corncob varied between 17.26 and 18.89 MJ/kg, and 3.23 and 5.66 GJ/m3, respectively. High torrefaction temperature and residence time lead to low solid yield; however, liquid and gas yields increase with torrefaction temperature and residence time. The solid yields varied from 27.57 to 52.23%, while the liquid and gas yields varied from 31.56 to 44.78% and 16.21 to 27.65%, respectively. The properties of corncob improve after torrefaction and are suitable for solid fuel application.

Furfural and hydrogen production from corncob via tandem chemical and electrochemical approach

Furfural and hydrogen co-production from raw corncob was demonstrated via the tandem chemical/electrochemical route. The operating conditions for furfural production were optimized with AlCl3 catalyst in a water/CPME biphasic system. A high furfural yield (85%) was obtained via chemical conversion by implementing an AlCl3 catalyst in a biphasic solvent system. The furfural waste from the chemical conversion was electrochemically upgraded into hydrogen with a 0.48% weight yield implementing a FeCl3 electrochemical mediator. The energy consumption for hydrogen evolution from waste furfural residue is 50% lower than water electrolysis. The facts indicate that a novel and promising method for the co-production of furfural and hydrogen from renewable biomass is developed.

Biocomposites from biobased polyamide 4,10 and waste corn cob based biocarbon

Development of polyamide 4,10 (PA 4,10) from renewable resources is a positive step towards replacement of traditional polyamides. The environmental impact of PA 4,10 is further improved through incorporation of sustainable biocarbon (BioC) filler derived from agro-residues, specifically corn cob. Pyrolysis improved filler stability at high temperatures required for PA 4,10 processing as opposed to raw corn cob, with biocomposites in the present work having an elevated biocontent to 76%. Corn cob BioC pyrolyzed at 350, 500, and 900 °C was characterized to elucidate its interactions with PA 4,10, finding a pyrolysis temperature of 350 °C providing strong interfacial adhesion via particle encapsulation. Biocomposites maintained similar mechanical and thermal properties as compared to neat polymer. Hindrance of crack propagation and rigidity of filler particles led to improvements in tensile modulus and heat deflection temperature by 6 and 12%, respectively. These composites provide a route to diminish reliance on petroleum-based polyamide products.

Agricultural bio-waste for removal of organic and inorganic contaminants from waste diesel engine oil

Corncob, an agricultural bio-waste, was used as adsorbent to remove organic and inorganic contaminants in waste lubricating oil (WLO) from diesel engine. To improve its adsorption capacity, corncob was modified with mixed solution of nitric acid, Hexadecyl trimethyl ammonium bromide and ethanol. Characterization results showed the crystallinity index of corncob enhanced 12%, which would be ascribed to the disruption of the dense lignin-carbohydrates structure in lignocellulose biomass by modification. The surface of modified corncob became smoother and porous. The adsorption results showed modified corncob had better removal rates to contaminants than raw corncob. For WLO with 80,000 km mileage, the removal rates to Fe, Al, Cu were enhanced from 19%, 6.4%, 48–27%, 27%, 53%, while that for oxide, sulphate, aromates, soot and insoluble resins were enhanced 1.7, 1.2, 3.0, 1.7 and 1.7 times. The reduction rate of total acid number to WLO with 40,000, 60,000, 80,000 km were enhanced 16%, 9%, 12% by modified corncob, respectively. The optimal adsorption condition was explored as adsorbing 60 min at 90 °C with 2% adsorbent. Corncob, with the advantages of low cost, good biodegradability and high adsorption capacity, could be used as alternative to conventional adsorbent for WLO.

Autocatalytic co-upgrading of biochar and pyrolysis gas to syngas

A new strategy is exploited toward dramatically increased carbon utilization efficiency of biomass fast pyrolysis by implementing co-upgrading of by-products (biochar and pyrolysis gas) of fast pyrolysis. Simultaneous autocatalytic conversion of biochar and pyrolysis gas is demonstrated using a fixed-bed reactor and an isothermal thermogravimetric analyzer. The reaction of corncob char with simulated pyrolysis gas reveals the feasibility of producing valuable CO and H2 under suitable reaction temperature (>800 °C). The reactivity of biochar and simulated pyrolysis gas increases with increasing potassium content. The raw corncob biochar exhibits high reactivity owing to its high indigenous potassium content. Furthermore, kinetic analysis demonstrates that the modified random pore model (MRPM) satisfactorily describes the reaction behavior of corncob biochar and CO2. The activation energy calculation verifies that the co-upgrading of raw corncob biochar and pyrolysis gas for the production of syngas is feasible at suitable temperature without further treatment.

Catalytic conversion of corncob to furfuryl alcohol in tandem reaction with tin-loaded sulfonated zeolite and NADPH-dependent reductase biocatalyst

In this study, tin-loaded sulfonated zeolite (Sn-zeolite) catalyst was synthesized for catalysis of raw corncob (75.0 g/L) to 103.0 mM furfural at 52.3% yield in water (pH 1.0) at 170 °C. This corncob-derived furfural was subsequently biotransformed with recombinant E. coli CG-19 cells coexpressing NADPH-dependent reductase and glucose dehydrogenase at 35 °C by supplementary of glucose (1.5 mol glucose/mol furfural), sodium dodecyl sulfate (0.50 mM) and NADP+ (1.0 μmol NADP+/mmol furfural) in the aqueous catalytic media (pH 7.5). Both sodium dodecyl sulfate (0.50 mM) and Sn4+ (1.0 mM) could promote reductase activity by 1.4-folds. Within 3 h, furfural was wholly catalyzed into furfuryl alcohol. By combining chemical catalysis with Sn-zeolite and biocatalysis with CG-19 cells in one-pot, an effective and sustainable process was established for tandemly catalyzing renewable biomass into furfuryl alcohol under environmentally-friendly way.