Pretreatment Of Corn Straw Research Articles

Mycelium-Doped Straw Biochars for Antibiotic Control.

Straw, a predominant agricultural residue, represents a significant waste product. Harnessing its potential is of paramount importance both in terms of research and economic value. In this study, chemically pretreated corn straw was infused with distinct microbial fungal mycelium variants and subsequently transformed into a series of biochars through a process involving carbonization and activation. The findings revealed enhancements in the specific surface area and total pore volume of mycelium-doped straw biochars compared to the original corn straw biochar (BCS). Additionally, discernible disparities were observed in their physical and chemical attributes, encompassing functional groups, surface chemistry, and micro-morphology. Notably, in water-based antibiotic removal experiments focusing on tetracycline hydrochloride (TH) and chloramphenicol (CP), the mycelium-doped straw biochars outperformed BCS. Their maximum adsorption capacities for TH and CP surpassed those of alternative adsorbents, including other biochars. Impressively, even after five cycles, the biochar exhibited a removal rate exceeding 80%, attesting to its robust stability. This study successfully emphasized the efficacy of incorporating fungal mycelium to enhance the adsorption properties of straw-based biochar, introducing a new theoretical basis for the development of lignocellulosic materials.

Rearing of Black Soldier Fly Larvae with Corn Straw and the Assistance of Gut Microorganisms in Digesting Corn Straw.

Corn straw is considered a renewable biomass energy source, and its unreasonable disposal leads to resource waste and environmental pollution. Black soldier fly (Hermetia illucens L.) larvae (BSFL) facilitate the bioconversion of various types of organic wastes. In this study, we found that 88% of BSFL survived, and 37.4% of corn straw was digested after 14 days of feeding with corn straw. Contrary to expectations, the pretreatment of corn straw with alkaline hydrogen peroxide did not promote its digestion but rather reduced the growth and survival rates of BSFL. Acinetobacter, Dysgonomonas, and unclassified Enterobacteriaceae were the abundant genera in the BSFL gut fed with corn straw. Compared with the standard diet, the relative abundances of carbohydrate metabolism genes, such as the gene abundances of β-glucosidase and α-glucosidase, were higher with corn straw as the substrate. These results suggested that the gut microbial community could regulate suitable and functional microorganisms in response to the substrates. Furthermore, four cellulase-producing strains, namely Klebsiella pneumoniae, Proteus mirabilis, Klebsiella oxytoca, and Providencia rettgeri, were isolated from the guts of corn straw BSFL. These four strains helped increase the conversion rates of corn straw, the weights of BSFL, and survival rates. In summary, we reared BSFL with corn straw and discovered the functions of gut microorganisms in adapting to the substrates. We also isolated four cellulase-producing strains from the BSFL guts and declared the benefits of BSFL digesting corn straw.

Rumen fluid pretreatment promotes anaerobic methane production: revealing microbial dynamics driving increased acid yield from different concentrations of corn straw.

In this work, the corn straw (CS) with concentrations of 3%, 6%, and 9% (w/v) were pretreated by rumen fluid (RF) and then used for batched mesophilic biogas production. The results showed that after a 6-day pretreatment, volatile fatty acid (VFAs) production of 3.78, 8.27, and 10.4 g/L could be found in 3%, 6%, and 9%, respectively. When concerning with biogas production, the highest accumulative methane production of 149.1 mL CH4/g volatile solid was achieved by 6% pretreated CS, which was 22% and 45% higher than 3% and 9%, respectively. Also, it was 3.6 times higher than the same concentration of unpretreated CS. The results of the microbial community structure analysis revealed that the 6% CS pretreatment not only maintained a microbial community with the highest richness and diversity, but also exhibited the highest relative abundance of Firmicutes (45%) and Euryarchaeota (3.9%). This high abundance was conducive to its elevated production of VFAs and methane. These findings provide scientific reference for the utilization of CS and support the development of agricultural waste resource utilization and environmental protection.

Enhanced adsorption of dye wastewater by low-temperature combined NaOH/urea pretreated hydrochar: Fabrication, performance, and mechanism.

The highly stable biomass structure formed by cellulose, hemicellulose, and lignin results in incomplete conversion and carbonization under hydrothermal conditions. In this study, pretreated corn straw hydrochar (PCS-HC) was prepared using a low-temperature alkali/urea combination pretreatment method. The Massloss rateof cellulose, hemicellulose, and lignin from pretreated biomass, as well as the effects of the pretreatment method on the physicochemical properties of PCS-HC and the adsorption performance of PCS-HC for alkaline dyes (rhodamine B and methylene blue), were investigated. The results showed that the low-temperature NaOH/urea pretreatment effectively disrupted the stable structure formed by cellulose, hemicellulose, and lignin. NaOH played a dominant role in solubilizing cellulose and the combination of low temperature and urea enhanced the ability of NaOH to remove cellulose, hemicellulose, and lignin. Compared to the untreated hydrochar, PCS-HC exhibited a rougher surface, a more abundant pore structure, and a larger specific surface area. The unpretreated hydrochar exhibited an adsorption capacity of 64.8% for rhodamine B and 66.32% for methylene blue. However, the removal of rhodamine B and methylene blue by PCS-BC increased to 89.12% and 90.71%, respectively, under the optimal pretreatment conditions. The PCS-HC exhibited a favorable adsorption capacity within the pH range of 6-9. However, the presence of co-existing anions such as Cl-, SO42-, CO32-, and NO3- hindered the adsorption capacity of PCS-HC. Among these anions, CO32- exhibited the highest level of inhibition. Chemisorption, including complexation, electrostatic attraction, and hydrogen bonding, were the primary mechanism for dye adsorption by PCS-HC. This study provides an efficient method for utilizing agricultural waste and treating dye wastewater.

Pre-treated corn straw fiber for fiber-reinforced concrete preparation with high resistance to chloride ions corrosion

Chloride ions erosion is a negative factor for concrete sustainable usage. Fiber addition is a potential solution, which promotes a tight concrete structure formation resulting in the resistance of chloride ions. Corn straw is a kind of crop waste widely sourced that can be used as sustainable concrete reinforcement material. The traditional recycling method of corn straw including burnt as straw ash is not environment friendly. This work aims to pre-treat corn straw fiber (CSF) by some convenient methods (untreated, water-treated, alkali-treated) and add treated CSFs directly into concrete to prepare fiber-reinforced concrete with excellent mechanical properties and high resistance ability to chloride ions. The component content of different treated CSFs was tested to study the fibers composition and microstructure changes. The heat of hydration, compressive strength, and flexural strength were tested to study the hydration degree and the effect of different treated CSFs on the concrete mechanical performance. The rapid chloride permeability (RCPT) and chloride migration (RCM) tests were designed to study the reinforced concretes chloride ions resistance ability change. In addition, to further explore the mechanism of mechanical performance and chloride ions resistance ability change, water absorption rate (WAR) and mercury intrusion porosity (MIP) were tested to provide more supporting information from the micro-level. It is concluded that CSF treated by Na2SiO3 has the least impurities and a rougher surface with a larger specific surface area bonding with the cement substrate. Compared to the original concrete, the compressive strength of CSF concrete, WT-CSF concrete, and NT-CSF concrete increased by 15.7 %, 17.8 %, and 33.4 % respectively. The results of RCM and RCPT show a decreasing trend with different treated CSFs addition, the NT-CSF concrete shows the greatest decrease with 20.1 %, and 17.5 %, respectively. Except for the rougher surface and less impurities of CSF, the improvement of mechanical performance and chloride ions resistance ability is mainly due to treated CSF, especially the NT-CSF contributes to a denser structure formation based on the MIP and WAR test results. The viscosity of Na2SiO3 solution acts as a binder that helps to tighten the bonding between substrate and CSF. The water adsorbed by CSF and the alkaline environment provided by Na2SiO3 facilitates hydration decreasing the chloride ions migration. At the same time, the cellulose in CSF containing many hydroxyl and carboxyl groups further contributes to the concrete chloride ion resistance improvement due to its weak conductivity and the binding force of ions exchange.

Bioethanol production from corn straw pretreated with deep eutectic solvents

BackgroundDeep eutectic solvents (DESs) have gained increasing attention as alternative solvents of environmental unfriendly solvents for biomass pretreatment. ResultsIn this study, bioethanol production from DES-pretreated corn straw was investigated. The results revealed effective lignin removal from corn straw after pretreatment with choline chloride/oxalic acid (C:O), choline chloride/glycerol (C:G), or choline chloride/urea (C:U) DESs. After pretreatment with DESs, cellulose conversion significantly increased to 96.51% from 44.35% in the case of untreated corn straw. The best performance was obtained after the pretreatment of corn straw with C:O with a mass ratio of 1:15 at 120°C for 6 h, and this was mainly attributed to high lignin removal (60.60%). Another experiment showed that corn straw pretreated with C:G had a cellulose conversion of 86.82%, a glucose yield of 63.57%, and an ethanol yield of 54.86%. ConclusionsOverall, this study demonstrated that the pretreatment of corn straw by a suitable DES can lead to efficient bioethanol production.How to cite: Liu J, Wang C, Zhao X, et al. Bioethanol production from corn straw pretreated with deep eutectic solvents. Electron J Biotechnol 2023;62. https://doi.org/10.1016/j.ejbt.2022.12.004.

Boosting enzymatic degradation of cellulose using a fungal expansin: Structural insight into the pretreatment mechanism

The recalcitrance of cellulosic biomass greatly hinders its enzymatic degradation. Expansins induce cell wall loosening and promote efficient cellulose utilization; however, the molecular mechanism underlying their action is not well understood. In this study, TlEXLX1, a fungal expansin from Talaromyces leycettanus JCM12802, was characterized in terms of phylogeny, synergy, structure, and mechanism of action. TlEXLX1 displayed varying degrees of synergism with commercial cellulase in the pretreatment of corn straw and filter paper. TlEXLX1 binds to cellulose via domain 2, mediated by CH–π interactions with residues Tyr291, Trp292, and Tyr327. Residues Asp237, Glu238, and Asp248 in domain 1 form hydrogen bonds with glucose units and break the inherent hydrogen bonding within the cellulose matrix. This study identified the expansin amino acid residues crucial for cellulose binding, and elucidated the structure and function of expansins in cell wall networks; this has potential applications in biomass utilization.

Study on biogas production from corn straw pretreated by compound microorganisms

The pretreated corn straw is pretreated by Fomes fomentarius, Trichoderma adaptatum and the compound microbial agent of Fomes fomentarius and Trichoderma adaptatum under the same conditions. Then biogas was produced by anaerobic fermentation of pretreated straw. According to the experimental results, it has been found that the straw pretreatment with complex microorganisms can not only promote the process of straw anaerobic fermentation biogas production, but also improve the gas production and gas production efficiency, among which the compound microbial agent pretreatment shows the best effect. Compared with the untreated straw, the degradation of lignin and cellulose in straw pretreated with compound microbial agent is much higher, and the lignin content is decreased from 16.6% to 6.8%, and the cellulose content is decreased from 32.3% to 19.8%. Besides, the gas production of compound microbial agent pretreatment has increased by 14.86%, the gas production time is 6 d earlier, the gas production peak is 17 d earlier, the volume gas production rate reaches 2.008 mL/(mL⋅d), and the gas production rate of raw materials reaches 526.66 mL/g. The straw pretreatment with only Fomes fomentarius also has a good effect. However, the effect of straw pretreatment by Trichoderma adaptatum is poor, which has indicated that straw pretreatment by lignin-degrading strain plays an important role in improving the anaerobic fermentation efficiency of straw.

Optimization of synergistic degradation of steam exploded corn straw by lytic polysaccharide monooxygenase R17L and cellulase

Hundreds of millions of tons of corn straw are available each year, and its main component is crystalline cellulose, which is currently underutilized by enzyme preparations, resulting in a waste of resources. The synergistic action of lytic polysaccharide monooxygenase (LPMO) and cellulase can significantly improve the conversion efficiency of cellulose, and then generate bioenergy or other valuable chemicals. In this study, corn straw was first pretreated with steam explosion at 200 °C for 3, 6, 9 and 12 min, and its chemical composition was analyzed. It was found that the hemicellulose content gradually decreased, and the cellulose content tended to increase as the pretreatment time increased. The results on the degradation of different pretreated corn straw showed that LPMO mutant R17L (Guo et al., 2020) and cellulase had the best synergistic effect on corn straw pretreated at 200 °C for 3 min. Comparing the results of degradation of corn straw at different pH, it was found that the reducing sugar produced by the degradation of corn straw at pH 6.0 were higher than that at pH 7.0. By analyzing the synergistic effect of different doses of R17L and cellulase, the optimal enzyme cocktail was 4 mg of R17L and 0.2 mL of commercial cellulase per gram of corn straw. Finally, by analyzing the surface morphology of corn straw under different enzymatic systems, it was found that the corn straw degraded by R17L in synergy with cellulase was the most fragmented, indicating that R17L disrupted the structure of corn straw, thus providing more operable sites for cellulase to achieve efficient conversion of biomass.

Lewis base enhanced neutral deep eutectic solvent pretreatment for enzymatic hydrolysis of corn straw and lignin characterization

In order to improve the pretreatment behavior of neutral deep eutectic solvent (DES), a novel method was proposed by using three types of Lewis base (sodium carbonate, sodium sulfite and sodium acetate as catalysts to pretreat corn straw at 120 °C for 3 h. As compared to DES, DES with Na2SO3, DES with NaAC and DES with Na2CO3, all can remove most of hemicellulose and lignin in pretreated corn straw. Meanwhile, the 94.5% of glucose yield was obtained treated by DES with Na2CO3 and was approximately five-fold higher than that of the untreated substrate at an enzyme loading of 15 FPU/g material. The regenerated lignin displayed well-preserved structures, and possessed a high purity (more than 84%), narrow molecular weight distribution (PDI <2.4), excellent thermal stability. Overall, this work provided detailed analysis for efficient deconstruction of corn straw for future industrialized application.

Improving anaerobic digestion of corn straw by using solid-state urea pretreatment

The resistant structure and high carbon/nitrogen ratio (C/N) of cellulosic substrate are the barriers during their anaerobic digestion (AD). Solid-state urea pretreatment was developed in this study to pretreat corn straw and adjust C/N ratio simultaneously for the downstream AD of corn straw. Results showed solid-state urea pretreatment was efficient in lignin removal and achieved the highest lignin reduction of 7.06% with C/N ratio = 15 during pretreatment. Scanning electron microscopy demonstrated the destruction of the dense structure by pretreatment, which benefited to the hydrolysis of corn straw. The cumulative methane yields of the pretreated corn straw ranged from 234.07 to 250.03 mL/g VS, which were obviously higher than that of the untreated corn straw. The maximum methane yield of 250.03 mL/g VS was achieved with C/N = 15 during pretreatment, which was 23.91% higher than that of the untreated group. In addition, AD digestates from the pretreated groups had 9.62% higher nutrients than that from the untreated group. The solid-state urea pretreatment can destroy the dense structure of corn straw and regulate the C/N ratio during AD, thus benefit the methane production and fertilizer use of the digestate, which is a potential choice during the AD of cellulosic substrate.

Influence of acid-washed pretreatment on the pyrolysis of corn straw: A study on characteristics, kinetics and bio-oil composition

Corn straw was washed using hydrochloric acid in this study. The properties of biomass and pyrolysis characteristics and the bio-oil components were examined systemically. The results showed acid washing removed the most metals in corn straw, improved the contents of cellulose and hemicellulose and reduced the activation energy of pyrolysis process. FTIR (Fourier transform infrared) spectra displayed some differences in peak transmittances between the original and pretreated corn straw. The GC–MS (Gas chromatography-mass spectrometer) analysis showed the major oxygenated components in bio-oil including furans, ketones, acids, phenols and aldehydes were efficiently destroyed by hydrochloric acid pretreatment, while the alcohols and sugars content increased significantly. A significant decrease of furans content was observed, especially the benzofuran, 2,3-dihydro-, from 7.23 % to 0%. D-allose and D-Erythro-Pentose, 2-deoxy- have been found in pretreated corn straw, which implied that more value-added chemicals could be obtained by hydrochloric acid washing.

The Influence of Corn Straw Extrusion Pretreatment Parameters on Methane Fermentation Performance.

The aim of the study is to determine the energy consumption of the extrusion-cooking process of corn straw under various conditions (screw speed, moisture content), water absorption measurements and water solubility indices as well as biogas efficiency evaluation. The extrusion-cooking of corn straw was carried out using a single screw extruder with L/D = 16:1 at various rotational screw speeds (70, 90, and 110 rpm) and with various initial moisture content of raw material (25 and 40%). Prior to the process, the moisture content of the raw material was measured, and next, it was moistened to 25 and 40% of dry matter. For example, at 70 rpm extruder screw speed, the temperature range was 126–150 °C. Energy consumption of straw pretreatment through extrusion-cooking was assessed in order to evaluate the possibility of using the process in an agricultural biogas plant. Biogas and methane efficiency of substrates after extrusion was tested in a laboratory scale biogas plant and expressed as a volume of cumulative methane production for fresh matter, dry matter, and dry organic matter. Pretreated corn straw moistened to 25% and processed at 110 rpm during the extrusion-cooking processing produced the most advantageous effect for methane and biogas production (51.63%) efficiency as compared to corn straw without pretreatment (49.57%). Rotational speed of the extruder screw influenced biogas and methane production. With both dry matter and dry organic matter, the increase of rotational speed of the extruder screw improved the production of cumulated biogas and methane. Pretreatment of corn straw has a positive effect on the acquisition of cumulated methane (226.3 Nm3 Mg−1 for fresh matter, 243.99 Nm3 Mg−1 for dry matter, and 254.83 Nm3 Mg−1 for dry organic matter). Preliminary analysis of infrared spectra revealed changes in the samples also at the molecular level, thus opening up the possibility of identifying marker bands that account for specific degradation changes.

Effects of different pretreatment methods on the structural characteristics, enzymatic saccharification and photo-fermentative bio-hydrogen production performance of corn straw

In this study, the effects of different pretreatment methods, including hydrothermal, acid, alkali, acid-heat, and alkali-heat on the structural characteristics, enzymatic saccharification and photo-fermentative bio-hydrogen production performance of corn straw were investigated. Results revealed that all the studied pretreatments effectively destroyed the corn straw structure and improved its enzymatic saccharification potential. The alkali-heat and alkali pretreatment showed significant advantage in reducing sugars release, and the highest total reducing sugar concentration of 23.07 g/L was obtained under the pretreatment condition of 2% NaOH-Heat. The maximum cumulative hydrogen yield of 137.76 mL/g TS was achieved from 2% NaOH pretreated corn straw, while corn straw pretreated with 4% NaOH-heat had the minimum cumulative hydrogen yield of 44.20 mL/g TS. These results suggest that appropriate pretreatment can effectively destroy the corn straw structure and enhance its enzymatic saccharification and hydrogen production performance.

Promoting air gasification of corn straw through biological pretreatment by biogas slurry: An initiative experimental study

The development of biomass gasification is subject to low quality of gas with low heating value and high tar concentration. A new biological pretreatment method by using biogas slurry (BS) with different moisture content (40–80 wt%) and retention time (1–7 days) was advanced for promoting air gasification of corn straw (CS). The considerable NH4+-N, appropriate pH and abundant microbes in BS made it effective for CS pretreatment. The dry matter loss of pretreated CS was recorded, the properties of CS and the pretreated CS were comparatively analyzed, and also the kinetic studies. Air gasification experiments were performed in a horizontal tube furnace at 1000 °C.The delignification reaction of BS made disordered and incompact structure of CS with the improved surface area, and decreased the activation energy for chemical reaction. The higher moisture content and longer retention time contributed to the optimal gasification performance. Considering the time and energy conservation, the intermediate 60 wt% moisture content and retention time 5 days was proposed. Compared with the raw CS, the LHV (7.15 MJ/Nm3) increased 1.15 MJ/Nm3, and tar content decreased 21 wt%. This proved efficient and low cost to produce bioenergy from CS, meanwhile, reducing BS and minimizing its potential pollution.

Gasification of lignocellulosic biomass pretreated by anaerobic digestion (AD) process: An experimental study

Biomass gasification was subject to poor quality of gas with low heating value and high tar concentration. Anaerobic digestion (AD) was a biological process resulting in lignin enrichment and structure change of biomass which were beneficial to further gasification. Without going into any economic details, downdraft fixed bed gasification of corn straw (CS) pretreated by AD process was thus proposed and performed in our lab. The properties of CS and the pretreated CS (ADCS) were comparatively analyzed, and the influence of AD pretreatment with different retention time (7 d, 14 d, 21 d, 28 d) on gasification under 600 °C–800 °C was investigated. The results indicated that by degrading holocellulose, AD pretreatment enhanced the gasification property of CS with enriched lignin and catalytic elements (P/Ca/Fe/Al), and the destroyed structure with increased surface area for reactants transfer. Lower heating value (LHV) and cold gas efficiency (CGE) increased with AD pretreatment retention time and topped at 14 d, and then slightly decreased. Compared with CS, the values of LHV and CGE derived from short pretreatment time (7–14 d) increased by 0.76–0.82 MJ/Nm3 and 8.7–10.69% at 600 °C, 1.21–1.3 MJ/Nm3 and 11.71–13.18% at 700 °C, and 0.54–0.86 MJ/Nm3 and 5.49–8.06% at 800 °C, respectively. Under the optimum pretreatment time 14 d and gasification temperature 800 °C, the LHV and CGE were 6.83 MJ/Nm3 and 73.62%. Tar content of ADCS decreased with pretreatment retention time and gasification temperature. Under 800 °C, with extension of pretreatment retention time, the tar content decreased by 30 wt%, 35 wt%, 45 wt% and 56 wt%. The results seemed to be interesting and valuable in promoting biomass gasification.

Separation and characterization of cellulose I material from corn straw by low-cost polyhydric protic ionic liquids

Separation of cellulose Ι material from biomass with high efficiency by using ionic liquid (IL) is still challenging. In this work, three low-cost polyhydric protic ammonium-salt ILs (about $1000/t) based on sulphonethane anion were synthesized via one-step protonation reaction and firstly applied in the pretreatment of corn straw. After study on the influence of selected process parameters, such as extraction time, extraction temperature and the IL recycling, 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium methanesulfonate ([BHEM]mesy) exhibits the highest efficiency with the content of cellulose up to 90 wt% in the cellulose material obtained at 140 °C for 6 h. Characterization analysis of the cellulose products certified that the cellulose materials maintain the same crystal structure of cellulose I as native corn straw. Gas chromatography–mass spectrometry and mass spectrometry methods were conducted to explore the possible separation mechanism. [BHEM]mesy shows the prospect of industrialization for cellulose I material separation from biomass owing to its low-cost and high-efficiency characteristics.

Pretreatment of corn straw using the alkaline solution of ionic liquids

In the present work, the pretreatment of corn stalk with the solution of 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) ionic liquid containing NaOH was explored for its lignin removal. The effects of reaction temperature, reaction time, and solid-liquid ratio on the lignin removal efficiency were determined by the response surface methodology (RSM). The pretreatment conditions were optimized by the Box-Behnken design and the comparative study of the composition and structure of corn straw before and after the pretreatment to be: reaction temperature 98.5 °C, reaction time 1.31 h, and solid-liquid ratio 1:8.7. Under the optimized conditions, the cellulose and hemicellulose contents of the corn straw were increased to 85.69% and 9.1%, respectively, and the lignin content was reduced to 2.27% with the lignin removal efficiency up to 87.4%.

Effects of waste sources on performance of anaerobic co-digestion of complex organic wastes: taking food waste as an example

Few studies have addressed how to blend wastes for anaerobic co-digestion. This study investigated the effects of waste sources on anaerobic co-digestion (AcoD) performance, by varying the quality of food wastes (FWs) from six sources in Xi’an region, China that were individually co-digested with pre-treated corn straw and cattle manure. These effects were analysed in terms of their volatile solid (VS) ratios, C/N ratios, and the chemical composition of the FWs. The results indicated that the VS ratios were not suitable as a common mixture method because the VS ratios at which the best methane potentials occurred differed significantly among the six FW groups. The C/N ratios within a 17–24 range resulted in better methane potentials when the FWs were co-digested with other wastes. Synergistic effects were found among the carbohydrates, proteins, and lipids of the FWs; however, the optimum ratios of these components could not be determined. Thus, the C/N ratio is recommended as a mixture method when co-digesting FWs with other organic wastes in selected region.

The pre-treatment of corn straw in the bioethanol production in China

Pre-treatment, a critical step for the utilization of cellulose, has close connection with processing cost and downstream technology. Corn straw, rich in cellulose, is a good source for bioethanol production. The writers have compared various pre-treatment methods of corn straw, in order to find out the most promising one for China’s bioethanol development.