Improvement of Methane Production from Corn Stalk for Whole Slurry Anaerobic Co-digestion Under Hydrothermal Wastewater Pretreatment

Corn stalk hydrothermal wastewater(CSHW)was used as a pretreatment for whole-slurry anaerobic co-digestion instead of conventional acid pretreatment.CSHW pretreatment was conducted at 20℃,35℃and 50℃for 3,6 and 9 h,after which all experimental groups were digested at 35℃for 24 days.This pretreatment method efficiently broke the lignocellulose structure of the corn stalk.Different from the volatile fatty acids(VFAs)content,the pH and RS contents were relatively higher than those of the control during the pretreatment process.Furthermore,the highest methane production[185.03 mL•g-1 VS(volatile solid)]was achieved at 55.46%under 35℃in 6 h,which was higher than that of the normal corn stalk anaerobic digestion.The VFAs contents and pH increased compared to CK upon the addition of NaOH to adjust pH,and the RS content also increased slightly due to the degradability of lignocellulose during the whole-slurry anaerobic co-digestion.This work provided a potential method to sustainably treat wastewater and improve fermentation performance.

Degradation of corn stalk by the composite microbial system of MC1

The composite microbial system of MC1 was used to degrade corn stalk in order to determine properties of the degraded products as well as bacterial composition of MC1. Results indicated that the pH of the fermentation broth was typical of lignocellulose degradation by MC1, decreasing in the early phase and increasing in later stages of the degradation. The microbial biomass peaked on the day 3 after degradation. The MC1 efficiently degraded the corn stalk by nearly 70% during which its cellulose content decreased by 71.2%, hemicellulose by 76.5% and lignin by 24.6%. The content of water-soluble carbohydrates （WSC） in the fermentation broth increased progressively during the first three days, and decreased thereafter, suggesting an accumulation of WSC in the early phase of the degradation process. Total levels of various volatile products peaked in the third day after degradation, and 7 types of volatile products were detected in the fermentation broth. These were ethanol, acetic acid, 1,2-ethanediol, propanoic acid, butanoic acid, 3- methyl-butanoic acid and glycerine. Six major compounds were quantitatively analysed and the contents of each compound were ethanol （0.584 g/L）, acetic acid （0.735 g/L）, 1,2-ethanediol （0.772 g/L）, propanoic acid （0.026 g/L）, butanoic acid （0.018 g/L） and glycerine （4.203 g/L）. Characterization of bacterial cells collected from the culture solution, based on 16S rDNA PCR-DGGE analysis of DNAs, showed that the composition of bacterial community in MC1 coincided basically with observations from previous studies. This indicated that the structure of MC1 is very stable during degradation of different lignocellulose materials.

Preparation of active carbons from corn stalk for butanol vapor adsorption

Active carbons(ACs) were prepared through chemical activation of biochar from whole corn stalk(WCS)and corn stalk pith(CSP) at varying temperatures using potassium hydroxide as the activating agent. ACs were characterized via pore structural analysis and scanning electron microscopy(SEM). These adsorbents were then assessed for their adsorption capacity for butanol vapor. It was found that WCS activated at900 °C for 1 h(WCS-900) had optimal butanol adsorption characteristics. The BET surface area and total pore volume of the WCS-900 were 2330 m2/g and 1.29 cm3/g, respectively. The dynamic adsorption capacity of butanol vapor was 410.0 mg/g, a 185.1% increase compared to charcoal-based commercial AC(143.8 mg/g).

A facile ionic liquid approach to prepare cellulose fiber with good mechanical properties directly from corn stalks

It is very difficult to directly spin the lignocellulose without pretreatment.Ionic liquids(ILs)are promising solvent to dissolve lignocellulose to prepare cellulose fiber.However,the degree of cellulose polymerization(DP)is reduced when lignocellulose is dissolved in ILs,and the lignin removal rate is low.The elongation at break and tensile strength of the fibers obtained by spinning the lignocellulose dissolved in ILs are poor.In this paper,preparing cellulose fiber directly from lignocellulose based on dissolving corn stalk via[C4mim]Cl-L-arginine binary system is achieved.It shows that the removal rate of lignin can reach 92.35%and the purity of cellulose can reach 85.32%after corn stalk was dissolved at 150℃C for 11.5 h when the mass fraction of arginine is 2.5%.The elongation at break of fiber reached 10.12%and the tensile strength reached 420 MPa.It is mainly due to the fact that L-arginine not only inhibits the degradation of cellulose but also promotes the delignination.Without any pulping or pretreatment,preparing cellulose fibers via direct dissolution and extrusion may provide a simple and effective way to prepare many novel cellulose materials.

Feed Production for Tenebrio molitor L. by Fermentation of Corn Stalks

In order to reduce the economic costs for breeding Tenebrio molitor L. and increase the utilization rate of corn stalk, with corn, wheat bran and corn stalk as the raw materials, 13 different compound feed were designed by Minitab （R） 15.1.0.0. The design was then divided into two groups based on addition or without addition of vegetable leaves to study the effects of compound feed and vegetable leaves on growth and de- velopment of T. molitor. The results showed that body weight, duration, crude protein content and pupation rate of larvae and emergence rate of adults were significantly affected by compound feed and vegetable leaves （ P 〈 0.05）. The larvae bred with feed 5 had the largest body weight, with the shortest duration; the larvae bred with feed 3 had the highest pupation rate; the larvae bred with feed 7 had the highest crude protein content; the adult bred with feed 9 had the largest emergence rate. Overall breeding effect of feed 7 ＋ vegetable leaves was better than any other groups, with ideal indicators, higher utilization rate and lower breeding cost. Its formula was w （wheat bran） = 33.33%, w （corn） = 33.33%, w （corn stalks） = 33.33%. Therefore, the growth of T. molitorwas significantly affected by feed types, and feed 7 ＋ vegetable leaves could be promoted in the production.

Pretreatment of Corn Stalk by Steam Explosion

A steam explosion pretreatment, which is one of the best ways of pretreating plant stalk, is applied at various severities to corn stalk. It could effectively modify the super-molecular structure of corn stalk and defibrating corn stalk into individual components. The relationship between yield of reducing sugar and the operating conditions, including temperature, pressure of steam explosion pretreatment and acidity, is also established. Experimental results prove that the steam explosion substantially increases the yield of reducing sugar, and the optimal condition for steam explosion is as follows: the pressure is 2.0 MPa, the pressure-retaining time 300 s, the initial acid concentration 1% and the acid treatment time 24 h.

Study on Humic Acids of the Soil Applied with Corn Stalk by Spectroscopy Measurements

Spectroscopy measurements （Fourier transform infrared differential spectroscopy, Carbon-13 nuclear magnetic resonance spectrometry, Matrix-assisted laser resorption/ionization-time of flight mass spectrometry） were performed to study the humic acids of the soil applied with corn stalk. The results showed that after incorporation of corn stalks into the soil, the soil humic acid （HA） changed significantly in different stages. During first 60 days, new HAs were formed by polymerization and seems to be similar to that of initial HAs from composting corn stalk, some little molecular organic matters also reacted with soil HAs and turned into parts of soil HAs. After 60 days of the corn stalk residue incorporation, new HAs were formed by polymerization of decomposed lignin molecules, some methylenes transformed into methyls and methoxyls since the 90th day. Application of corn stalk led to the increase of aliphatic components in soil HAs, the decrease in aromatic components of soil HAs and the suppression in oxidation degree of soil HAs. The average molecular weight of soil HAs also declined because of application of corn stalk.

Interfacial Modification of Corn Stalk Cellulose Reinforced Used Rubber Powder Composites Treated with Coupling Agent

Corn stalk cellulose(CS)/used rubber powder(RP)composites were prepared by mixing,the silane coupling agent 3-Mercaptopropyl trimethoxysilane(KH590),r-Aminopropyltrieth oxysilane(KH550),isopropyl dioleic(dioctylphosphate)titanate(HY101)and bis-(γ-triethoxysilylpropyl)-tetrasulfide(Si69)were used to modify the interface of composites.The effects of the CS and coupling agents on the mechanical properties,thermal properties,interfacial morphology and structure of the composites were investigated,respectively.The results showed that the addition of CS could effectively improve the mechanical properties of the composites.Compared with the untreated composites,the interfacial bonding between CS and RP was significantly improved by the coupling modification treatment,and the tensile strength and elongation at break of composites with Si69 increased by 3.13 MPa and 10%,respectively,the Si69 showed the best coupling modification effect,followed by KH590,then KH550 and HY101 when the CS content was 25 pph(part per hundred)and coupling agent 1.5 pph,and the thermal decomposition temperature increased by 30℃.

A Study of Adsorption of Modified Corn Stalk on PCP

The comprehensive utilization of corn stalks is an urgent agricultural and environmental problem to be solved in China.In this test,we use corn stalk as adsorbent for adsorption of PCP in water,and compare the impact of three modification methods(alkali treatment,pyrolysis,graft copolymerization) on corn stalk adsorption properties.Results show that the modified corn stalk's adsorption of PCP is increased from 5.4 mg/g to 13.9 mg/g,17.8 mg/g and 22.5 mg/g,respectively; the corn stalk after graft copolymerization and modification has the greatest adsorption capacity; after modification,both the adsorption capacity and adsorption rate constant of corn stalk on PCP are increased significantly.

Adsorption Kinetics of Cupric Ions on Mixture of Modified Corn Stalk and Modified Tomato Waste

The water crisis is an increasingly severe global problem that may be reduced by reusing wastewater after suitable treatment methods. Nowadays, biosorption is one of the main parts of environmental technology which could adsorb heavy metals. This paper describes the adsorption of Copper(II) ions from aqueous solution using a mixture of corn stalk and tomato waste which were oxidized with nitric acid. Kinetic and isotherm studies were carried out by studying the effects of parameters such as concentration dosage, time and pH. It was found that the maximum sorption capacity of the mixture of modified corn stalk and modified tomato waste (qm = 25 mg/g) was higher than the modified corn stalk (qm = 20.8 mg/g). Analysis indicated that pseudo-second-order kinetics controlled the adsorption rate and it has been proposed to correlate the experimental data well.

Effect of High Concentrate Corn Stalk Particle Size on Physical State and Production Performance of Lactating Dairy Cows

In order to realize the application of corn stalk in cow feed, we designed experiments to explore the effect of a certain proportion of corn stalk on the performance of lactating dairy cows. 9 multiparous mid-lactating cows were allocated at random to three groups, each containing 3 intact cows. The trial consisted of three periods and three dietary treatments with a 3 × 3 Latin square design. The diets were normal concentrats plus dried corn stalk chopped to 5 - 8 cm long (N), high concentrates plus dried corn stalks chopped to a length of approximately 5 - 8 cm by a mower (H) while the milled corn stalks were passed through a pulviser with a 2 cm pore size (MH). Each cow was measured for dry matter intake (DMI), ruminal pH, rumen fermentation, selective feeding behavior and production performance. The results showed that MH led to a significantly higher intake of DM, neutral detergent fiber (NDF), forage NDF (FNDF), acid detergent fiber (ADF), crude protein (CP) and organic matter (OM) than N and H (P < 0.05). Cows fed H and MH showed similar selective feeding behavior, while those fed H showed various selectivity for the dietary component. MH resulted in a significantly higher milk production (P < 0.05), and tended to have a higher milk fat production than N (P = 0.055). There were no significant differences in the milk components (P = 0.424) and lactose (P = 0.113) between cows fed N and MH. The high-concentrates plus milled corn stalk diet can increase the milk yield under the premise of normal rumen pH in dairy cows, thereby generating higher economic benefits. And milled corn stalk can effectively inhibit the cow’s selective eating of low-quality roughage.

Selective hydrolysis of lignocelluloses from corn stalk in an ionic liquid

Although lots of basic studies , such as the hydrolysis and dissolution of lignocelluloses has made great progress in recent years , the hydrolysates containing complex mixture of pentose and hexose are very hard to be separated , and these process sometimes cause serious environmental problems in practical application of cellulose polymer degradation science.Herein , an efficient two-stage method for selective hydrolysis of lignocelluloses biomass is being developed in this paper by controlling of pH in an ionic liquid.The lignin-hemicelluloses matrix in corn stalk was hydrolyzed into xylose in 23.1% yield in the first stage ; and cellulose-rich residues from the first stage was by farther hydrolyzed to provide a glucose in 26.9%yield.Structure of the products were identified by 13 C NMR.It should be mentioned that , the ionic liquid which can be regenerated and reused throughout the process. The present work significantly opens an a new path to utilize each component of lignocellulose as raw materials producing biofuels , renewable energy and fine chemicals.

Effects of Different Pretreatment Modes on the Enzymatic Digestibility of Corn Leaf and Corn Stalk

Corn leaf and corn stalk were pretreated with only hot water and 0.1% sulfuric acid at 160℃ or 200℃, respectively. For hot water pretreatment, the pH of corn stalk hydrolysate decreased more rapidly than that of corn leaf as the reaction time increased. On the contrary, the pH of corn leaf hydrolysate increased more than that of corn stalk with diluted acid addition. Increasing temperature enhanced the xylose dissolution rate and increased cellulose digestibility. Compared with hot water, 0.1% sulfuric acid addition improved the xylan removal and the enzymatic hydrolysis of both corn leaf and corn stalk residue. Much less xylan must be removed to achieve the same cellulose digestibility for the corn leaf as that for the corn stalk; 55% digestibility was obtained when only 32% xylan was removed from corn leaf, whereas corn stalk required removal of about 50% of the xylan to achieve the same di- gestibility. Overall, the descending order of enzymatic digestibility was: dilute acid hydrolysate of corn leaf > dilute acid hydrolysate of corn stalk > water-only hydrolysate of corn leaf > water-only hydrolysate of corn stalk. Finally, one separate pretreatment strategy was developed to transfer corn leaf and corn stalk to fermentable sugars for fur- ther bioenergy production.

Fabrication and Characterization of Willemite Scaffolds Using Corn Stalk as a Novel Bio Template for Bone Tissue Engineering Applications

In this paper,we used Corn Stalk(CS)as a renewable and economical bio template to fabricate willemite scaffolds with the potential application in skull bone repair.CS was used as a sacrificial template to synthesize the scaffolds.Willemite scaffolds with the chemical formula of Zn2SiO4 and pore size in the range of 3 to 10µm could be successfully synthesized by soaking CS in the willemite solution for 24 h and sintering at 950°C for 5 h.The porosity of the samples was controlled by the soaking time(between 12 and 48 h)in the willemite solution from 5 to 35%,respectively.The properties of these scaffolds showed a good approximation with cranial bone tissue.In addition,cytotoxicity assays(MTT)were performed on Human Bone Marrow Stromal cells(HBMSc)and A172 human glioblastoma cell lines by direct and indirect culture methods to estimate their toxicity for bone and nerve cells,respectively.Alkaline Phosphatase(ALP)activity and DAPI/Phalloidin cell staining were also performed to investigate the efficiency of the scaffolds for bone tissue engineering applications.The results showed that the scaffolds had good biocompatibility with both HBMSC and A172 cells,noticeable improvement on ALP activity,and great apatite formation ability in Simulated Body Fluid(SBF).All the evidence ascertained that willemite scaffolds made by corn stalks could be a useful candidate for bone tissue engineering applications.

Design of Bionic Saw Blade for Corn Stalk Cutting

The serrated incisors of grasshopper [Chondracris rosea rosea （De Geer）] possess an advantageous capacity for cutting plant fiber. Inspired by this special geometrical structure of incisors, bionic saw blade was designed and manufactured. MATLAB software digital image processing technology was used to obtain outer margin profile from stereomicroscope pho- tograph of the serrated incisors. The outer margin profile of incisors was fitted and expressed by six-order polynomial function. To compare the cutting capacity of bionic and traditional saw blades, the internodes of dry corn stalks were cut perpendicularly. Cutting force-deformation characteristics were obtained by universal testing machine. The results of cutting experiments show that the maximum cutting force of bionic saw blade was 128.26 N, which is 15.87% lower than 152.45 N of traditional saw blade; the average cutting force of bionic saw blade was 51.56 N, which is 28.17% less than 71.78 N of traditional saw blade. Meanwhile, the cutting energy consumption of bionic saw blade was 8.95 J, which is 12.85% less than 10.27 J of traditional saw blade. Overall, the bionic saw blade can lead to noticeable reduction of the cutting force and energy. These results will be helpful for designing cutting elements of corn stalk harvesting, biomass size reduction and other processing machinery.

Classification and comparison of physical and chemical properties of corn stalk from three regions in China

Corn stalk samples from Anhui,Jiangxi and Shanghai were used as test materials.Their physical,chemical and thermo-chemical engineering characteristics were analyzed.The similarities and differences in properties of corn stalk from the three regions were determined using SIMCA-P and SPSS software in order to obtain a proper energy utilization method of corn stalk.The results show that the corn stalk from Shanghai has significant differences from the samples of Jiangxi and Anhui.In particular,the following properties of corn stalk from Shanghai such as the contents of cellulose,calcium(Ca),iron(Fe),crude ash,volatile matter,carbon(C),nitrogen(N),and oxygen(O)are significantly different from those of Jiangxi and Anhui samples(P<0.05).While other properties such as the contents of magnesium(Mg),copper(Cu),zinc(Zn),moisture,hydrogen(H),and sulfur(S)have no significant difference among samples of three regions.Compared with the corn stalk in Anhui and Jiangxi,the Shanghai samples are more suitable for the production of ethanol because of their higher ratio of cellulose to hemi-cellulose content.Because of its high content of ash and low calorific value,the Shanghai corn stalk is suitable for the gasification process instead of for direct combustion or bio-oil production.The research can provide a reference for raw material selection for biomass energy production and utilization.

Effects of internal factors on surface wettability of corn stalk rind

Corn stalk is one of heterogeneous materials with anisotropy and variability.As the rind of corn stalk consists of rich lignin and cellulose similar to wood properties,and possessing high mechanical strength,then can be used as raw material of stalk artificial board and paper.The corn stalk rind has significant differences in fiber morphology,chemical composition and mechanical properties at different heights.Nano-SiO2 composite material contained in the epidermis of corn stalk rind is not conducive to exert adhesive into a board.To study board-making technology by intact corn stalk rind,the wettability of corn stalk rind at different sampling heights is necessary to be analyzed by keeping or removing the epidermis.To analyze the surface wettability difference,the contact angle with water,element compositions and the chemical compositions of corn stalk rind at different sampling heights were studied before and after removal of epidermis.A Fourier transform infrared(FTIR)analysis was performed.The results showed that the removal of the epidermis could significantly improve the hydrophilicity of corn stalk rind.Before removal of the epidermis,the varying contents of elements including C and Si dominate the surface wettability differences at different sampling heights of corn stalk.With an increase in the sampling height,the mass fraction of C increases while that of Si decreases,which result in increasing hydrophilicity.After removal of the epidermis,the surface wettability of corn stalk rind is mainly determined by the mass fraction of hemicellulose,and the higher the sampling height,the larger the mass fraction of hemicellulose resulting in the increase of hydrophilicity.

Preparation of bio-oil by catalytic pyrolysis of corn stalks using red mud

Red mud is a solid waste residue with alkaline nature(pH>12)-originating from the Bayer process in the production of alumina,which was probed in catalytic pyrolysis to determine its feasibility as a solid catalyst for bio-oil formulation.The red mud was characterized using X-ray fluorescence,XRD(X-ray diffraction),TG-DTG(thermogravimetry-derivative thermogravimetry),BET(surface area and pore size analyzer)measuring and testing techniques.Experiments of non-catalytic and catalytic pyrolysis of 40-60 mesh size corn stalk powder were channelled for bio-oil production in a fixed bed reactor.It was ascertained that adding different proportions of red mud had minute influence on bio-oil production rate and product distribution.The study signaled that liquid yield from the catalytic pyrolysis was lower than that from non-catalytic pyrolysis.Through a series of bio-oil characterization,it was encountered that the most obviously change in the bio-oil from catalytic pyrolysis was significant acidity reduction(pH>4).Meanwhile,the content of ketones and phenols was enhanced.Hence,the co-processing of agricultural waste and by-products alumina industry may offer an economical and environmentally friendly way of catalytic pyrolysis with abbreviating the red mud environmental effects.

Highly efficient enzymolysis and fermentation of corn stalk into L-lactic acid by enzyme-bacteria friendly ionic liquid pretreatment

Ionic liquids(ILs)have been widely used in the pretreatment of biomass.However,the effects of residual ILs on the enzymolysis and fermentation of biomass are still unknown.Therefore,a large quantity of water-washing is usually followed after biomass pretreatment to eliminate the inhibition of residual ILs on subsequent hydrolysis and fermentation steps.In this work,the effect of choline glycine([Ch][Gly])concentration on the activity of cellulase and Bacillus sp.strain P38 was systematically investigated to explore the impacts of residual ILs on enzymolysis and fermentation.The results confirmed that the activities of them were almost not inhibited in low concentrations(less than 0.5 wt%)of[Ch][Gly].Under optimal pretreatment conditions,the maximum cellulose digestibility was 99.23%.Enzymatic hydrolysate was suitable for L-lactic acid fermentation without appreciable inhibition,and the highest sugar-acid conversion rate of 96.33%was obtained by simplified detoxification.This work provides an economic route to produce fermentable sugar and L-lactic acid,which shows an industrial application prospect in lignocellulosic biorefinery.