Biomass Cornstalk Research Articles

Brown sugar enhancing strength of corn stalk biomass bricks

In order to enhance the strength of corn stalk biomass brick, corn stalk fiber, calcium hydroxide, and brown sugar water solution were mixed and moulded into biomass brick. The corn stalk fiber content was 15 wt% and the calcium hydroxide content was 85 wt% in bricks. Brown sugar water was added to calcium hydroxide at 1 wt% of the calcium hydroxide content. Compressive strength and flexural strength increased with the increasing concentration of brown sugar water solution. Moisture content, density, and drying shrinkage rates were not affected significantly by the concentration of brown sugar water solution. But compressive strength, flexural strength, and tensile strength were affected significantly by the concentration of brown sugar water solution. Compared with the control brick, the compressive strength increased by 51.03%; flexural strength increased by 64.24%; tensile strength increased by 40.91%. Therefore, brown sugar could significantly enhance the compressive strength, flexural strength, and tensile strength of biomass brick. The reason was that brown sugar promoted calcium hydroxide to form more calcium carbonate. The presence of brown sugar helped CO2 diffuse inside the bricks because slow carbonation of the brick surface significantly delayed pore plugging around the surface of the bricks. The research results provided the scientific base for brown sugar enhancing the strength of corn stalk biomass brick and it was interesting to use corn stalk effectively. It was of great significance to the application of sugar adhesives and the research and development of organic/inorganic composite building materials.

Study on double dovetail tenon and mortise combination of corn stalk biomass bricks

The dovetail mortise and tenon structure is creatively applied to the combination of corn stalk biomass bricks, which changes the cement slurry bonding method between bricks. The double dovetail tenon is made of cement and sand and water, and but the dovetail mortise in brick is molded. The weight loss and drying density of double dovetail tenon decrease with the increasing cement and sand contents, and increase with the increasing water content. Tensile strength and strength-weight ratio of tenon increase with the increasing cement content from 20.8% to 26.9%, however, decrease from 26.9% to 33.3%. They increase with the increasing sand content from 46.5% to 51.1%, but decrease from 51.1% to 62.3%. They increase with the increasing water content from 11.8% to 17.4%, but decrease from 17.4% to 18.9%. The tensile strength of three kinds of cement dovetail joint is determined by the internal bonding strength of dovetail mortise. The creative structure is interesting for the application of biomass bricks because it saves labor and construction time.

Potential of Corn Stalk Biomass as Biosorbent in Adsorption of Mercury (Hg) Metal Contaminants

Corn stalks are an agricultural waste that is commonly found in Indonesia. Corn stalks have a high enough cellulose content which has functional groups that can be used as biosorbents. This study aims to optimize the adsorption of corn stalk waste to mercury metal ions and then determine the adsorption capacity and adsorption constant of the Langmuir and Freundlich isotherm model. This research begins with corn stalk preparation, delignification, characterization using FTIR and SEM, determination of optimization of biosorbent weight, pH of Hg solution, contact time, and concentration of Hg solution, then applied to mercury metal contamination waste. Optimization of the weight of biosorbent in the range 0.4-1.2 grams, pH of the Hg solution is 2-4, contact time is 60-120 minutes, and concentration of the Hg solution of 30-100 g/L with a solution volume of 50 mL. Furthermore, determination of mercury levels, manufacture of standard series, and testing using ICP-OES. Followed by the determination of Langmuir and Freundlich's adsorption isothermal model. The results of this study indicate that the optimum conditions for the adsorption process occur at the weight of the biosorbent 1.2 grams, pH of the Hg 3 solution, contact time of 90 minutes, and concentration of Hg solution of 40 ppb with a solution volume of 50 mL. The application of biosorbent to metal contamination waste with adsorbed Hg concentration obtained 27.5772 ppb in 50 mL of waste solution with an adsorption efficiency of 88.44%. In the determination of Langmuir and Freundlich isotherms, a match was found for Langmuir adsorption isothermals with an adsorption capacity of 0.00333 mg Hg/g biosorbent and b = 176.8256.

Facile preparation of all cellulose composite with excellent mechanical and antibacterial properties via partial dissolution of corn-stalk biomass

All-cellulose composite (ACC) was directly fabricated by the partial-dissolution welding of cellulose microfibers from agro-residual corn stalks treated with low-concentration ZnCl2 solvent (10–40 %). The solvent infiltrated deeply into nano/micro-scaled pores of cellulose fibers to facilitate the free migration of the disordered chains among the cellulose network while leaving the fiber core undissolved. Then, these disordered chains would entangle and regenerate to serve as a welded layer to bond the undissolved microfibril core in the solvent removal process. Such welding achieved exceptional mechanical (the tensile strength and Young's modulus of 49.9 MPa and 6.6 GPa, respectively), antibacterial (log removal value (LRV) of 4.8 and 3.0 for E. coli and S. aureus, respectively) and biodegradable properties of the multifunctional ACCs. It is worthwhile noting that the excellent antimicrobial effect is attributed to the sufficient contact of these microbes with ZnO NPs that were converted from the residual Zn2+ in ACCs. After five recycling processes, the elimination efficiency could still maintain a high LRV of 2.0–3.8. This high durability of ACC microbicidal activity was originated from strong twining interactions of cellulosic fibrils with in-situ synthesized ZnO NPs. This strategy was proven to be a facile and economical pathway to fabricate functional all-cellulose composites.

Sugarcane Bagasse and Corn Stalk Biomass as a Potential Sorbent for the Removal of Pb(II) and Cd(II) from Aqueous Solutions

Heavy metal pollution in the water supply is a serious environmental problem that affects human health around the world. The goal of this study was to investigate the adsorption behaviour of sugarcane bagasse (SB) and corn stalk (CS) biomass for Pb(II) and Cd(II) removal from metal-contaminated water. When the doses of biomass were increased in solutions containing Pb(II) and Cd(II), the SB and CS showed a trend of increasing metal removal efficiency. The removal efficiency of biomass for Pb(II) decreased as the pH of the solution increased from 5.0 to 7.0, with an optimum pH range of 5 to 6. However, pH has little influence on the removal efficiency of biomass for Cd(II). Adsorption equilibrium is reached in about 15 min. Adsorption for at least four cycles improves Pb(II) removal efficiency (up to 98 %) in solutions containing only Pb(II). The best fitness of the adsorption isotherm to Freundlich suggests multilayer adsorption of metal ions onto CS. Higher qmax and Kf suggest that SB and CS have a greater affinity for Pb(II) than for Cd(II). Pb(II) adsorption potential was found in biomass derived from SB and CS, but it was less effective as a Cd(II) adsorbent. For application in environmental clean-up, we suggest further study on the structural modification of biomass to enhance its metal removal capacity, the regeneration of biomass for better results, and field trials for practical application. HIGHLIGHTS The adsorption behaviour of sugarcane bagasse and corn stalk biomass for Pb(II) and Cd(II) removal from metal-contaminated water was studied The removal efficiency of Pb(II) increases with increased doses of biomass and decreases with increased solution pH and metal initial concentrations Adsorption for at least four cycles improves metal removal efficiency in the case of Pb(II) Freundlich’s isotherm suggests multilayer adsorption of Pb(II) and Cd(II) onto corn stalk biomass Higher qmax and Kf values suggest that sugarcane bagasse and corn stalk have a higher affinity for Pb(II) than Cd(II)

Recovery of microbial community in strongly alkaline bauxite residues after amending biomass residue

The aim of this study was to characterize the effects of cornstalk biomass amendments on microbial communities in bauxite residues (BRs) by phylogenetic analysis. Improvements in soil geochemical, physical, and biological properties were assessed to identify the major factors controlling microbial community development in BRs. After one year of incubation, the salinity and structure of the amended BRs had gradually improved, with pH dropping from 11.39 to 9.89, the exchangeable sodium percentage (ESP) dropping from 86.3% to 35.2%, and the mean weight diameter (MWD) rising from 0.12 mm to 0.38 mm. Further analysis of community level physiological profiles (CLPP) showed that the microbial utilization of different carbohydrates had shifted significantly, in addition to increases in the diversity index H′ (0.7–7.34), U (2.16–3.14), and the average well color development (0.059–1.08). Over the one-year outside incubation, the dominant fungal phyla in the BRs had shifted gradually from Ascomycota (85.64%) to Ascomycota (52.07%) and Basidiomycota (35.53%), while the dominant bacterial phyla had shifted from Actinobacteria (38.47%), Proteobacteria (21.39%), and Gemmatimonadetes (12.72%) to Actinobacteria (14.87%), Proteobacteria (23.53%), and Acidobacteria (14.37%). Despite these shifts, microbial diversity remained lower in the amended BRs than in the natural soil. Further redundancy analysis indicated that pH was the major factor driving shifts in the bacterial community, while aggregates were the major factor driving shifts in the fungal community. This study demonstrated that amendment with cornstalk biomass shifted the microbial community in the BRs from halophilic groups to acidogenic groups by improving the soil environmental conditions.

High Selectivity and Reusability of Biomass-Based Adsorbent for Chloramphenicol Removal.

Recently, biomass-based materials have attracted increasing attention because of their advantages of low cost, environment-friendly and nonpollution. Herein, the feasibility of using corn stalk biomass fiber (CF) and Fe3O4 embedded chitosan (CS) as a novel biomass-based adsorbent (CFS) to remove chloramphenicol (CAPC) from aqueous solution. Structure of CFS was characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and zeta potential techniques. The effects of solution pH, adsorption time and ion strength on the adsorption capacity were examined. Adsorption isotherms obtained from batch experiments were better fitted by Langmuir model compared with Freundlich model, Dubinin–Radushkevich model and Temkin model. Adsorption kinetic data matched well to the pseudo-second order kinetic model. CAPC adsorption was endothermic, spontaneous, and entropy-increasing nature on CFS. In addition, the CFS could be separated by an external magnetic field, recycled, and reused without any significant loss in the adsorption capacity of CAPC. Based on these excellent performances, there is potential that CFS can be considered as a proficient and economically suitable material for the CAPC removal from the water environment.

Separation and characterization of biomass components (cellulose, hemicellulose, and lignin) from corn stalk

Representative hemicellulose, milled wood lignin (MWL), and cellulose were directly separated from corn stalk, and their main chemical content was determined using NREL methods. The chemical elements, chemical groups, and molecular structure of corn stalk biomass components (hemicellulose, MWL, and cellulose) were analyzed by elemental analysis, Fourier transform infrared, and nuclear magnetic resonance spectroscopy analyses．The results showed that the purity of the biomass components separated from corn stalk was high, the degree of damage was relatively small, and their own structural characteristics were relatively intact. The hemicellulose that was separated from corn stalk was mainly composed of L-arabino-β-(1→4)-D-glucuronoxylan units. There were also sugar residues attached to the main chain in the form of side chains, such as D-glucopyranose, galactose, glucuronic acid, and galacturonic acid. The isolated cellulose consisted of glucosyl linked by β-(1→4)-glucosidic bond. The MWL separated from corn stalk has a GSH-type of β-O-4 structure, and the contents were as follows, in order of more to less: guaiacyl (G), p-hydroxyphenyl (H), and syringyl (S) units. Biomass components with high purity were separated from corn stalk, and their respective structure and composition were understood, which provides a foundation for the subsequent high-value utilization of corn stalk.

Sulfonated porous biomass-derived carbon with superior recyclability for synthesizing ethyl levulinate biofuel

The synthesis of ethyl levulinate (EL) via esterification of levulinic acid (LA) with ethanol, which can be derived from biomass, has become an attractive topic since EL can be applied in many fields, such as fuel additives for petroleum and biodiesel, food additives and fragrance. Herein, the sulfonated porous carbon catalysts derived from the rinds of corn stalk biomass wastes were prepared by using sulfuric acid and phosphoric acid as the sulfonating agent and activator, respectively. The preparation parameters were optimized based on the catalytic activity for LA esterification with ethanol and the acid density of the corresponding catalysts. Also, various reaction factors were optimized to improve the catalytic efficiency over the optimal sulfonated corn stalk-derived carbon (s-CSC). Under the conditions of reaction temperature 80 °C, catalyst dosage 5 wt%, ethanol-to-LA molar ratio 5.0:1 and reaction time 8 h, the LA conversion reached 94% and 93% catalyzed by s-CSC and the optimal porous catalyst (s-p-CSC), respectively. Noticeably, benefitting from the hierarchical porous structure with large surface area, s-p-CSC exhibited much better recyclability than s-CSC. This work offers a highly effective solid acid catalyst for the synthesis of biofuel.

Oxalic Acid from Corn Stalk for Photocatalytic Reduction of Cr(VI)

Cr(VI) is toxic species of chromium in the aquatic environment. The reduced species, Cr (III), has lower toxicity than Cr(VI). The change of Cr(VI) species to Cr(III) can be conducted by photocatalytic reduction using oxalic acid as an oxidant with the aid of Fe(III) as a catalyst. Oxalic acid can be isolated from the biomass waste of corn stalk. This research aimed to isolate oxalic acid from corn stalk biomass as an oxidator for Cr(VI) photocatalytic reduction. The oxalic acid was isolated from corn stalks powder using NaOH, precipitated with the addition of CaCl2, acidified with H2SO4, and then crystalized to form the oxalic acid crystals. The photocatalytic reduction was carried out in a closed reactor equipped with two of 30-watt UV lights. About 30 mg of oxalic acid was used to reduce 300 mg/L Cr(VI) with the presence of 4 ml Fe(III) 100 mg/L as a catalyst. The process was conducted for 120 minutes while stirring. The reduction efficiency was calculated from the differentiation of the initial Cr(VI) concentration to the final ones. Cr(VI) concentrations were measured as Cr(VI)-diphenylcarbazide complex compound at pH 2 that could be detected at 540 nm. The results showed that the isolated oxalic acid has hydroxyl and carbonyl groups at 3441 cm−1 and 1627 cm−1 respectively identical with the oxalic acid standard. The crystals have melting point at 103°C. It could be used effectively to reduced Cr(VI) up to 45.9 %.

Simultaneous production of propionic acid and vitamin B12 from corn stalk hydrolysates by Propionibacterium freudenreichii in an expanded bed adsorption bioreactor

Vitamin B12 and propionic acid that were simultaneous produced by Propionibacterium freudenreichii are both favorable chemicals widely used in food preservatives, medicine, and nutrition. While the carbon source and propionic acid accumulation reflected fermentation efficiency. In this study, using corn stalk as a carbon source and fed-batch fermentation process in an expanded bed adsorption bioreactor was studied for efficient and economic biosynthesis of acid vitamin B12 and propionic. With liquid hot water pretreated corn stalk hydrolysates as carbon source, 28.65 mg L−1 of vitamin B12 and 17.05 g L−1 of propionic acid were attained at 168 h in batch fermentation. In order to optimize the fermentation outcomes, fed-batch fermentation was performed with hydrolyzed corn stalk in expanded bed adsorption bioreactor (EBAB), giving 47.6 mg L−1 vitamin B12 and 91.4 g L−1 of propionic acid at 258 h, which correspond to product yields of 0.37 mg g−1 and 0.75 g g−1, respectively. The present study provided a promising strategy for economically sustainable production of vitamin B12 and propionic acid by P. freudenreichii fermentation using biomass cornstalk as carbon source and expanded bed adsorption bioreactor.

Modification of biochar with silicon by one-step sintering and understanding of adsorption mechanism on copper ions

Novel salt-based biochar was prepared by loading silicon (Si) on cornstalk biomass with “one-step sintering” technique. Manganese (Mn) was also used to modify biochar with the same method as a control. Surface morphology, elemental composition, crystal structure and surface area of “salt-based biochars” were analyzed by SEM + EDS, XRD, FTIR and BET, and the effects of the dosage of absorbent and pH of solution on the adsorption process were explored. Si and Mn could be successfully attached on the biochar surface as oxide forms. SiBC exhibited a dense and agglomerated surface, while MnBC was a kind of porous and rough materials. The optimal adsorption capability would realize when putting 2 g/L of biochar composites at pH = 5–6. Adsorption isotherms, adsorption kinetics, combine with FTIR and XPS were carried out to help to elaborate the adsorption mechanisms. The maximum adsorption capacity of Cu (II) was 152.61 mg/g on SiBC and it could reach at 97% of removal rate within 10 min when the concentration was 100 mg/L, while MnBC had to take 500 min to achieve the same adsorption effect, and reached 187.76 mg/g of maximum adsorption capacity. Langmuir model and pseudo-second-order model were more suitable for both SiBC and MnBC, which meant the monolayer and chemical adsorption were dominated. Surface complexation and precipitation was attributed to SiBC. Specialistic adsorption, ion exchange and intra-particle diffusion was put it down to MnBC.

De novo transcriptome analysis of Pleurotus djamor to identify genes encoding CAZymes related to the decomposition of corn stalk lignocellulose

CAZymes play a very important role in the biotransformation of corn stalk biomass, which is an important resource for sustainable development. Pleurotus djamor can produce CAZymes related to the decomposition of corn stalk lignocellulose biomass in sole corn stalk substrate; however, little is known about their encoding genes. In order to identify CAZymes encoding genes, RNA high-throughput sequencing of P.djamor was performed in this study. The results showed that a core set of 70 upregulated genes encoding putative CAZymes were revealed. They encode 19 kinds of CAZymes in total, of which there are 4 EGLs, 8 CBHs, 5 BGLs, and 12 LPMOs related to cellulose degradation, 8 XYNs, 1 XYL, 2 AGUs, 3 ABFs, 2 AGLs, and 2 AXEs related to hemicellulose degradation, and 5 LACCs, 2 MnPs, 5 VPs, 3 CDHs, 1 AAO, 1 GOX, 1 AOX, 2 GAOXs, and 3 GLOXs related to lignin degradation. This variety suggests that CAZymes may play a very important role in decomposing the lignocellulose biomass of corn stalk. This is the first study to report the de novo transcriptome sequencing of P.djamor, which will produce a dataset of genes encoding CAZymes, thereby laying the foundation to elucidate the degradation mechanism of corn stalk biomass and boost the biotransformation of corn stalk biomass resources.

Pyrolysis of corn stalk biomass briquettes in a scaled-up microwave technology

Pyrolysis of corn stalk biomass briquettes was carried out in a developed microwave (MW) reactor supplied with 2.45GHz frequency using 3kW power generator. MW power and biomass loading were the key parameters investigated in this study. Highest bio-oil, biochar, and gas yield of 19.6%, 41.1%, and 54.0% was achieved at different process condition. In terms of quality, biochar exhibited good heating value (32MJ/kg) than bio-oil (2.47MJ/kg). Bio-oil was also characterised chemically using FTIR and GC–MS method. This work may open new dimension towards development of large-scale MW pyrolysis technology.

Capacitive performance of porous carbon nanosheets derived from biomass cornstalk

Porous carbon nanosheets derived from naturally abundant cornstalk are reported as a high rate supercapacitor electrode in aqueous and solid-state PVA–KOH electrolyte.

Continuous production of biohythane from hydrothermal liquefied cornstalk biomass via two-stage high-rate anaerobic reactors.

BackgroundBiohythane production via two-stage fermentation is a promising direction for sustainable energy recovery from lignocellulosic biomass. However, the utilization of lignocellulosic biomass suffers from specific natural recalcitrance. Hydrothermal liquefaction (HTL) is an emerging technology for the liquefaction of biomass, but there are still several challenges for the coupling of HTL and two-stage fermentation. One particular challenge is the limited efficiency of fermentation reactors at a high solid content of the treated feedstock. Another is the conversion of potential inhibitors during fermentation. Here, we report a novel strategy for the continuous production of biohythane from cornstalk through the integration of HTL and two-stage fermentation. Cornstalk was converted to solid and liquid via HTL, and the resulting liquid could be subsequently fed into the two-stage fermentation systems. The systems consisted of two typical high-rate reactors: an upflow anaerobic sludge blanket (UASB) and a packed bed reactor (PBR). The liquid could be efficiently converted into biohythane via the UASB and PBR with a high density of microbes at a high organic loading rate.ResultsBiohydrogen production decreased from 2.34 L/L/day in UASB (1.01 L/L/day in PBR) to 0 L/L/day as the organic loading rate (OLR) of the HTL liquid products increased to 16 g/L/day. The methane production rate achieved a value of 2.53 (UASB) and 2.54 L/L/day (PBR), respectively. The energy and carbon recovery of the integrated HTL and biohythane fermentation system reached up to 79.0 and 67.7%, respectively. The fermentation inhibitors, i.e., 5-hydroxymethyl furfural (41.4–41.9% of the initial quantity detected) and furfural (74.7–85.0% of the initial quantity detected), were degraded during hydrogen fermentation. Compared with single-stage fermentation, the methane process during two-stage fermentation had a more efficient methane production rate, acetogenesis, and COD removal. The microbial distribution via Illumina MiSeq sequencing clarified that the biohydrogen process in the two-stage systems functioned not only for biohydrogen production, but also for the degradation of potential inhibitors. The higher distribution of the detoxification family Clostridiaceae, Bacillaceae, and Pseudomonadaceae was found in the biohydrogen process. In addition, a higher distribution of acetate-oxidizing bacteria (Spirochaetaceae) was observed in the biomethane process of the two-stage systems, revealing improved acetogenesis accompanied with an efficient conversion of acetate.ConclusionsBiohythane production could be a promising process for the recovery of energy and degradation of organic compounds from hydrothermal liquefied biomass. The two-stage process not only contributed to the improved quality of the gas fuels but also strengthened the biotransformation process, which resulted from the function of detoxification during biohydrogen production and enhanced acetogenesis during biomethane production.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0666-z) contains supplementary material, which is available to authorized users.

All-lignocellulosic fiberboard from corn biomass and cellulose nanofibers

In general, fiberboards are made of lignocellulosic fibers with synthetic adhesive to connect between fibers. Synthetic adhesives are usually non-biodegradable constituents and they cause health and environmental troubles. The present study aims to develop fiberboards from corn thermomechanical fibers reinforced with cellulose nanofibers. In this work, corn stalk biomass was used to produce high yield thermomechanical pulp (TMP) that was converted into binderless fiberboards. Cellulose nanofibers (CNF) were also added as reinforcing agent. The mechanical and physical properties of the resulting fiberboards were characterized and compared with commercial high density fiberboard (HDF) containing synthetic adhesives. Fiberboards with 0.5wt% CNF showed modulus of rupture of 43MPa, similar to that of commercial HDF. The highest mechanical performance was reached for fiberboards at 2wt% of CNF, with modulus of rupture of 52MPa. CNF was found to increase the resistance of the new all-lignocellulosic fiberboards when compared to the products made only with corn stalk fiber, and also when compared with commercial HDF.

Performance and microbial community of carbon nanotube fixed-bed microbial fuel cell continuously fed with hydrothermal liquefied cornstalk biomass

Hydrothermal liquefaction (HTL) is a green technology for biomass pretreatment with the omission of hazardous chemicals. This study reports a novel integration of HTL and carbon nanotubes (CNTs) fixed-bed microbial fuel cell (FBMFC) for continuous electricity generation from cornstalk biomass. Two FBMFCs in parallel achieved similar performance fed with cornstalk hydrolysate at different organic loading rates (OLRs) (0.82–8.16g/L/d). About 80% of Chemical oxygen demand (COD) and Total organic carbon (TOC) was removed from low-Biochemical oxygen demand (BOD)/COD (0.16) cornstalk hydrolysate at 8.16g/L/d, whereas a maximum power density (680mW/m3) was obtained at 2.41g/L/d, and a smallest internal resistance (Rin) (28Ω) at 3.01g/L/d. Illumina MiSeq sequencing reveals the diverse microbial structure induced by the complex composition of cornstalk hydrolysate. Distinguished from Proteobacteria, which a number of exoelectrogens belong to, the identified dominant genus Rhizobium in FBMFC was closely related to degradation of cellulosic biomass.

Adsorption Behavior of Rhodamine B and Methylene Blue by Chemical Modified Cornstalk Biomass

Cornstalk, a cellulosic agricultural waste material, was modified by citric acid to improve the adsorption of rhodamine B (RB) and methylene blue (MB) from aqueous media. Characterization of SEM and FTIR spectra confirmed that the surface morphology of adsorbent changed and carboxylic groups were introduced into the raw cornstalk by chemical modification. The effects of pH, contact time, initial concentration and the amount of dried adsorbent were studied in batch experiments. There was no significant difference in the dye concentration remaining when the pH was increased from 4.0 to 10.0. Several models were used to fit experimental data and the results showed that experimental data fitted the Langmuir model and pseudo-second order model best. Compared with 58.71 and 81.71 mg g-1obtained by CS (raw cornstalk), the maximum adsorption capacities for RB and MB were 203.0 and 245.6 mg g-1by using CCS (cornstalk modified with citric acid), respectively.

Enzymatic Hydrolysis and Succinic Acid Fermentation from Steam-Exploded Corn Stalk at High Solid Concentration by Recombinant Escherichia coli

Steam-exploded corn stalk biomass was used as the substrate for succinic acid production via lignocellulose enzymatic hydrolysis and fermentation. Succinic acid fermentation was investigated in Escherichia coli strains overexpressing cyanobacterium Anabaena sp. 7120 ecaA gene encoding carbonic anhydrase (CA). For the washed steam-exploded corn stalk at 30 % substrate concentration, i.e., 30 % water-insoluble solids (WIS), enzymatic hydrolysis yielded 97.5 g/l glucose solution and a cellulose conversion of 73.6 %, thus a high succinic acid level up to 38.6 g/l. With the unwashed steam-exploded corn stalk, though a cellulose conversion of 71.2 % was obtained in hydrolysis at 30 % solid concentration (27.9 % WIS), its hydrolysate did not ferment at all, and the hydrolysate of 25 % solid loading containing 3.8 g/l acetic acid and 168.2 mg/l furfural exerted a strong inhibition on succinic acid production.