Straw Fractions Research Articles

Experimental Study on the Thermal Performance of Rice Straw-Mortar Composite Materials

Thermal properties of mortar block can be improved through adding straw, which is related to the type, size, amount of the straw, and so on. In order to test the thermal insulation performance of rice straw-mortar composite materials, this paper adopted response surface methodology (RSM), which employed a four-factor, three-level Box-Behnken design regarding gypsum content (% mass fraction of gypsum), straw size (mm), straw content (% mass fraction of straw) and water content (g) of rice straw-mortar composite materials as independent variables. Thermal conductivity, thermal diffusivity and thermal resistance of composite materials were response variables. The straw content and water content extremely significantly affected all the responses; the straw size had extremely significant effect on the thermal resistance as well as significant effect on the thermal conductivity. According to the optimum solution of regression equations, the optimum values of thermal conductivity, thermal diffusivity and thermal resistance were 0.048 W (m K)−1, 0.163 mm2 s−1, and 12.743 K W−1, respectively. The optimization options of gypsum content, straw size, straw content and water content were 5.01%, 20 mm, 22.7% and 0.06 g, respectively. Due to the state change of pore water, thermal conductivity of rice straw-mortar composite materials containing free water decreased seriously after complete freezing and increased slightly after 15 times freeze-thaw. During first freezing process, the thermal conductivity increased obviously with the increasing of freezing time, then increased slowly. A theoretical basis was provided by the experimental results, which was essential for the study on the thermal performance of rice straw-mortar composite materials as well as the application of similar materials.

A simple laboratory flash apparatus for thermal diffusivity measurement: Modeling and application for composite material based on clay and straw

In this work. we have developed and tested a flash apparatus for thermal diffusivity measurement of building materials. After the test on homogeneous materials, this very inexpensive apparatus was then used to estimate the thermal diffusivity of some local materials based on clay and straw. To estimate this quantity, the measured temperature rise at the rear face of the sample was processed by solving analytically the transient heat equation based on a one-dimensional model with time-dependent convective boundary conditions. The obtained mathematical model takes into account the temporal shape f(t) of the heat pulse used to excite the front sides of the samples as well as four unknown parameters ie: the thermal diffusivity, the two Biots numbers related to the heat losses on the rear and the front sides and the maximum adiabatic temperature. For this purpose, the excitation form performed via a flashlight was experimentally measured and f(t) properly modeled by a first square form followed by a short exponential waning phase attributed to the thermal inertia of the used halogen lamps. Finally, the simultaneous estimation of the remaining unknown parameters was carried out by minimizing the sum of the quadratic differences between the mathematical model and the measured thermogram on the back faces of the samples. The precision and accuracy of the apparatus results were also examined by measuring the thermal diffusivity of several homogeneous building materials. The standard deviation in thermal diffusivity for the studied samples doesn’t exceed 4.72 %. Then, five samples from clay mixed with different mass fractions of straw are prepared and their thermal diffusivities are measured. The thermal conductivity and the heat capacity of these composite materials are experimentally achieved and their values are reported for comparative purposes. The thermal characterization shows a decrease of about 27.5 % in thermal diffusivity, 43.32 % in thermal conductivity and 4.40 % in heat capacity versus the increase of the straw mass fraction.

Maleic acid hydrotropic fractionation of wheat straw to facilitate value‐added multi‐product biorefinery at atmospheric pressure

AbstractWheat straw was rapidly fractionated using maleic acid (MA) as an acid hydrotrope at atmospheric pressure under a range of conditions. MA hydrotropic fractionation (MAHF) was very selective in dissolving lignin and hemicelluloses resulting in a cellulose‐rich water insoluble solids (WIS), which was evaluated for producing fibers through bleaching and cellulosic nanofibrils by fibrillation, as well as glucose through enzymatic saccharification. The residual lignin (RL) within the WIS has a low degree of condensation, which eased bleaching. The RL was also carboxylated through MAHF, which facilitated nanofibrillation to produce lignin‐containing cellulose nanofibrils. The carboxylation also aided enzymatic saccharification of WIS by decreasing nonproductive cellulase binding to RL through electrostatic repulsion between carboxylated (charged) RL and the cellulase at elevated pH (>cellulase isoelectric point). The dissolved lignin (DL) from MAHF also has a low degree of condensation, making it favorable for further catalytic conversion. Carboxylation improved DL antioxidant capability. MA is an FDA‐approved indirect food additive (21CFR175‐177) and is much less corrosive than other acids typically used for cellulosic fractionation. It is also less soluble which is a distinct and very promising advantage for acid recovery. Therefore, MAHF has notable advantages and significant potential for sustainable biorefinery.

Lignocellulosic biomass pre-treatment using low-cost ionic liquid for bioethanol production: An economically viable method for wheat straw fractionation

Low-cost Ionic Liquid (IL) is a promising method for the lignocellulosic biomass pretreatment to produce bioethanol. This study investigates utilizing low-cost IL, [TEA][HSO4], for wheat straw pretreatment. The pretreatment was investigated in conditions characterized by a temperature of 130 °C, a high solid-to-solvent load ratio of 1:5 g/g, and 20 wt % water to separate lignin and carbohydrates from the source, which would subsequently undergo enzymatic hydrolysis. The highest delignification rate of 80% and the hemicellulose removal rate of 64.45% were observed in the case of a 3-h pretreated sample with [TEA][HSO4]. Two biomass samples pretreated for 0.5 h and 3-h showed high glucose saccharification yield levels of 50.36 and 87.19%, respectively, and 78.23% xylose yield was achieved in 3-h pretreated sample in enzymatic hydrolysis with commercial enzyme CelluMax in 72 h. Ethanol production and yield of 3-h pretreated biomass reached 43.1 g/L and 84.34% of the maximum theoretical yield after 48 h of fermentation time. However, the yield of the untreated biomass was only 10.76%. Obtained results clearly demonstrated that pretreatment with low-cost IL prior to enzymatic hydrolysis led to higher ethanol yield due to successful delignification. The process developed in this study exhibited economic feasibility of this technique in industrial bioprocess.

Urea treatment of rice straw: A modelling approach of its degradation kinetics in the rumen

This study aimed to compare between rice straw and urea-treated rice straw with regard to their chemical composition and degradation kinetics in the rumen by employing a modelling approach. Data were collected from various journal articles that comprised of chemical composition (crude protein [CP], neutral detergent fiber [NDF], acid detergent fiber [ADF] and lignin) and degradation kinetic parameters of organic matter (soluble fraction, degradable, undegradable, degradation rate and lag time). Comparison was performed by using a statistical mixed model methodology in which treatments (control vs urea-treated rice traw) were considered as fixed effects whereas different studies were considered as random effects. These data were then used as parameters to build a dynamic model of rice straw degradation in the rumen. Results showed that urea treatment increased CP (P<0.001) while decreased NDF (P<0.01) contents of rice straw. The ADF and lignin contents were similar between the control and urea-treated rice straw. Proportion of degradable fraction and degradation rate of rice straw were enhanced due to urea treatment (P<0.001). However, the treatment did not influence soluble fraction and lag time of the material. Microbial biomass and total volatile fatty acid production in the rumen changed dynamically over time and the values were higher for the urea-treated rice straw.

APPLICATION OF MODERN BIOTECHNOLOGY METHODS TO IMPROVE SOIL FERTILITY

A person’s desire to improve the quality of life makes the individual reconsider the attitude towards the quality of consumed food. Despite the fact that the prices of natural products are several times higher than of those grown with the use of herbicides and pesticides, organic food is getting more popular in all countries around the world. Such products can only be received when crops are grown using organic farming methods, one of the principles of which is to increase the amount humus in the soil. The preservation of soil fertility can be ensured using the methods of modern biotechnology, which are based on the vital activity of microorganisms capable of converting organic matter from animal waste into environmentally friendly fertilizers. In animal husbandry, the main portion of agricultural waste is cattle and pig manure. The most economical way to dispose it is to use methane digestion, when biogas and fertilizers are obtained. However, when processing manure bedding materials in biogas reactors, the straw fractions and lignin–containing components of the bedding are not decomposed by bacteria and pass into the solid fraction of the fermented biomass unchanged, which is a problem. The infiltration of such an unprocessed residue into the soil leads to deterioration of soil properties. Thereby, the solid fraction of the fermented biomass requires additional processing to improve its agrochemical properties. Most expedient is to use vermicomposting, that is, process organic waste with the help of earthworms. Biohumus, or vermicompost, is one of the end products of this method. In this work, we studied the procedure of processing the solid fraction of fermented pig manure by Eisenia foetida compost worms (red Californian worm). In order to determine the optimal approach of vermicomposting, the experiment was planned. As a result, a high–quality organic fertilizer was obtained – biohumus –and the optimal parameters of the environment were determined(pH and humidity), at which the worms have the highest biological activity.

Biochemical properties of cellulolytic and xylanolytic enzymes from Sporotrichum thermophile and their utility in bioethanol production using rice straw

Production of cellulolytic and xylanolytic enzymes by Sporotrichum thermophile was enhanced using response surface methodology in solid-state fermentation (SSF) using wheat straw and cotton oil cake. Cellulolytic and xylanolytic enzymes were partially purified by ammonium sulfate precipitation followed by ion exchange and gel filtration chromatographic techniques. Xylanase of S. thermophile is neutral xylanase displaying optimal activity at 60 °C with Km and Vmax values of 0.2 mg/mL and 238.05 µmole/min, respectively. All cellulases produced by the thermophilic mold showed optimal activity at pH 5.0 and 60 °C with Km values of 0.312 mg/mL, 0.113 mg/mL, and 0.285 mM for carboxymethyl cellulase (CMCase), filter paper cellulase (FPase), and β-glucosidase, respectively and while Vmax values were 181.81, 138.88, and 66.67 µmole/min, respectively. The presence of various metal ions (Ca2+ and Co2+), chemical reagent (glutaraldehyde), and surfactants (Tween 80 and Triton X-100) significantly improved the activities of all enzymes. All the enzymes showed high storage stability under low temperature (−20 and 4 °C) conditions. Cellulolytic and xylanolytic enzymes resulted in enhanced liberation of reducing sugars (356.34 mg/g) by hydrolyzing both cellulosic and hemicellulosic fractions of ammonia-pretreated rice straw as compared to other pretreatment methods used in the study. Fermentation of enzymatic hydrolysate resulted in the formation of 28.88 and 27.18 g/L of bioethanol in separate hydrolysis and fermentation (SHF) process by Saccharomyces cerevisiae and Pichia stipitis, respectively. Therefore, cellulolytic and xylanolytic enzymes of S. thermophile exhibited ideal properties of biocatalysts useful in the saccharification of cellulosic and hemicellulosic fractions of rice straw for the production of bioethanol.

Pure Hydrolyzable Cellulose from Rice Straw, Wheat Straw and Sugarcane Bagasse by a Simple Scalable Two-Step Treatment

Utilization of amply available lignocellulosic biomass for a cost-effective conversion to renewable chemicals has proven more difficult than anticipated. Sustainable and viable fractionation of any biomass to its individual monomeric components for their further conversion to products at commercial scale therefore remains elusive. A rapid and scalable multi-step pretreatment strategy for fractionation of rice straw using a combination of dilute aqueous acid and aqueous alkali treatment steps under subcritical conditions was investigated. The process steps and parameters were optimized for yield and purity of the resulting biomass components. Effects of acid and alkali concentrations on the fractionation efficiency were studied in the range of 0.2% to 12% w/v at temperatures ranging from 110°C to 200°C for time spanning from 15 to 30 min. The simple optimum sequence of operations and conditions was found to be a diluteacid hydrolysis step at 130°C for 15 min with 2% HNO3 followed by the second treatment step at 130°C for 15 min with 2% NaOH. This combination gave 90% pure cellulose in more than 80% overall yield. Formation of furfurals in the hydrolysate was prevented significantly, and the cellulose obtained showed good amenability for enzymatic hydrolysis to sugars. The same process was applied to wheat straw and sugarcane bagasse, and the obtained results were found to be similar to those obtained for rice straw. The process was successfully scaled up to 50 L batch process with negligible deviations from smaller scale run results.

A flow-through reactor for fast fractionation and production of structure-preserved lignin

Viable biorefinery requires a robust and cost-competitive method of biomass fractionation. Here, we design green and efficient flow-through reactor for biomass fractionation. Aqueous formic acid was used as a solvent at mild temperatures. The time course study verified a rapid flow-through fractionation of wheat straw in 20 min at 130 °C involving synergetic actions of acid hydrolysis of hemicellulose and lignin dissolution. The obtained fractionation attained 76.3 % of lignin yield and 69.8 % of sugars yield without measurable degradation of hemicelluloses. More importantly, lignin fractionation showed well-preserved inter-unit linkages as indicated by the 76.4 % retention of aryl ether bond. The exponential model was established and well described the relationships between fractionation conditions and kinetics of lignin solubilization. This rapid flow-through reactor/fractionation promises to be a very practical equipment/strategy for biomass fractionation with competitive products.

Facilitating enzymatic hydrolysis with a novel guaiacol-based deep eutectic solvent pretreatment

Herein, we established a novel deep eutectic solvent (DES) using lignin-derived guaiacol as hydrogen bond donor (HBD). The sole ChCl/guaiacol system was found to be inefficient for the fractionation of wheat straw (WS), while the incorporation of trace AlCl3 significantly facilitated the degradation of hemicellulose and lignin, resulting in a complete enzymatic digestibility of the pretreated WS. Further, this study revealed that the DES-degraded lignin was readily precipitated during the washing process, and thus hindered the enzymatic hydrolysis of poplar and bamboo (with hydrolysis yield of 42.03% and 71.67%, respectively). Alkali washing offers a possible approach to remove the precipitated lignin, after which a near 100% hydrolysis yield was also obtained for poplar and bamboo.

High-Throughput Generation of Product Profiles for Arabinoxylan-Active Enzymes from Metagenomes

Metagenomics is an exciting alternative to seek carbohydrate-active enzymes from a range of sources. Typically, metagenomics reveals dozens of putative catalysts that require functional characterization for further application in industrial processes. High-throughput screening methods compatible with adequate natural substrates are crucial for an accurate functional elucidation of substrate preferences. Based on DNA sequencer-aided fluorophore-assisted carbohydrate electrophoresis (DSA-FACE) analysis of enzymatic-reaction products, we generated product profiles to consequently infer substrate cleavage positions, resulting in the generation of enzymatic-degradation maps. Product profiles were produced in high throughput for arabinoxylan (AX)-active enzymes belonging to the glycoside hydrolase families GH43 (subfamilies 2 [MG432], 7 [MG437], and 28 [MG4328]) and GH8 (MG8) starting from 12 (arabino)xylo-oligosaccharides. These enzymes were discovered through functional metagenomic studies of feces from the North American beaver (Castor canadensis). This work shows how enzyme loading alters the product profiles of all enzymes studied and gives insight into AX degradation patterns, revealing sequential substrate preferences of AX-active enzymes.IMPORTANCE Arabinoxylan is mainly found in the hemicellulosic fractions of rice straw, corn cobs, and rice husk. Converting arabinoxylan into (arabino)xylo-oligosaccharides as added-value products that can be applied in food, feed, and cosmetics presents a sustainable and economic alternative for the biorefinery industries. Efficient and profitable AX degradation requires a set of enzymes with particular characteristics. Therefore, enzyme discovery and the study of substrate preferences are of utmost importance. Beavers, as consumers of woody biomass, are a promising source of a repertoire of enzymes able to deconstruct hemicelluloses into soluble oligosaccharides. High-throughput analysis of the oligosaccharide profiles produced by these enzymes will assist in the selection of the most appropriate enzymes for the biorefinery.

Two‐Step Autohydrolysis Pretreatment: Towards High Selective Full Fractionation of Wheat Straw

AbstractPretreatment is necessary to increase the enzymatic digestibility of lignocellulosic biomass. Here, degradation reactions of solubilized pentoses to furfural and others are undesired regarding the reduced product yield and increasing downstream processing efforts. In this work, the use of the unit operation configuration was successfully shown to reduce degradation reactions. In the used two‐step autohydrolysis pretreatment, the reaction is stopped before degradation takes place. The pentoses are removed by water leaching to make them unavailable for degradation in a second autohydrolysis treatment. The overall sugars yield is increased, and the furfural formation is decreasing while maintaining the high lignin purity using the two‐step autohydrolysis pretreatment.

Why can hydrothermally pretreating lignocellulose in low severities improve anaerobic digestion performances?

A lignocellulosic residue, rice straw, was hydrothermally pretreated for the whole slurry anaerobic digestion. In contrast to the unpretreated rice straw, 110–120 °C pretreatment promoted biogas yield by 35%–38%, while only 14% promotion happened on the pretreatment at 180 °C. To understand why this improvement happened at lower severities, the pretreated rice straw at 90 °C, 120 °C, and 180 °C were selected for the further investigation, in which the liquor and solid fraction were separated for digestion, and compared with the whole slurry digestion. Results indicated more methane was released from the derived liquor of 180 °C than that of 90 °C and 120 °C, however, solid fraction did not exhibit significantly different methane yields (187.77–193.91 mL/g TS). These results suggested that the released soluble fraction from pretreatment could facilitate the methanogenesis. Furthermore, the released inherent soluble fraction in rice straw was mainly responsible for higher biogas yield at lower temperatures. Pretreatment at higher temperatures disintegrated the rice straw recalcitrance more, and intensified the release of soluble fraction accordingly. Consequently, the methanogenesis of whole slurry could be promoted at the initial digestion; the hydrolysis/acidification of the solid fraction in whole slurry was weakened greatly, which resulted in a lower biogas yield. This can also be proved by the evolution of dominant bacteria and archaea in the anaerobic digestion of whole slurry, separated solid and liquor fraction.

Residual nitrogen pools in mature winter wheat straw as affected by nitrogen application

Reduction of the amount of nitrogen (N) remaining in mature wheat straw is an essential challenge in order to boost grain protein and N use efficiency. However, very limited information is available on the composition of the residual N pools and how they are affected by N fertilization. Winter wheat was grown under field conditions at five different N levels ranging from 60 to 280 kg N ha−1. The fraction of straw N present in amino acids, chlorophyll, DNA, nitrate and lignin-associated compounds were analyzed separately in leaf blades, sheaths and stems. Total straw N concentration increased from 0.29 to 0.69% with increasing level of N application. The largest N pool consisted of amino acids in hydrolysable proteins, which comprised 50 to 70% of the residual N. Lignin-associated, non-hydrolysable N compounds constituted 13 to 16% of the total N, while non-protein N pools (mainly chlorophyll breakdown products and DNA) amounted to 5–14%. Protein-derived amino acids constituted the most abundant N pool in mature wheat straw. Despite a 2.5-fold increase in total straw N content, the relative proportion of the different residual N pools to the total N content in the straw did not change with N fertilization.

Comparison of conventional and automated freezing methods on PB2 rooster semen cryopreserved with glycerol and dimethylsulfoxide tris coconut-water extender

BackgroundPoultry semen cryopreservation remains an easy and promising way of preserving and transferring poultry germplasm. Standardizing and optimizing freezing procedure with natural extender may be a reliable step towards achieving better post-thawed sperm quality. This study was conducted to investigate the effects of four different freezing protocols (FP) on frozen rooster semen extended with tris coconut water extender (TCWE). A total of 20 roosters were used and trained for semen collection. TCWE was prepared by adding coconut water to tris buffer and kept at 37 °C. Semen was collected and pooled from the roosters and was evaluated for motility before dilution procedure. Three different concentrations (8, 10, and 15%) of two intracellular cryoprotectants glycerol and dimethylsulfoxide (DMSO) were supplemented in TCWE. Pooled semen was divided into six equal fractions, and TCWE containing cryoprotectants in different concentrations were diluted with the semen in ratio 1:2 (semen:extender). Diluted semen was manually filled in 0.25 ml straws and sealed. Semen straws were equilibrated for 4 h at 4 °C. Each straw fraction was further divided into four parts, and subjected to four FP (slow freezing 1, 2, 3 and fast freezing 4). Each FP was done on samples containing 8, 10, and 15% glycerol and 8, 10, and 15% DMSO. After each protocol, semen straws were finally deep into liquid nitrogen – 196 °C. After 48 h, the straws were thawed individually to evaluate post/thawed motility, viability, and membrane integrity. The experiment consists of three trials.ResultsAt 8% glycerol concentration, FP1 has significantly (P > 0.05) the highest percentage motility (73.33%) compared to FPs 2, 3, and 4 (56.68, 50.00, and 23.33% respectively). At 10% glycerol, FP2 had the highest motility (48.33%) and HOST (64.00%). At 15% glycerol, FP4 (fast freezing) had the highest percentage motility (71.67%), viability (76.33%), and HOST (71.67%). At 8%, DMSO concentrations FP4 had the highest significant (P > 0.05) motility, viability, and HOST. Ten percent and 15% DMSO revealed no significant (P > 0.05) difference in most parameters among all the FPS. DMSO performed better than glycerol irrespective of concentrations in all FPS on most parameters evaluated.ConclusionsFast freezing performed better with 15% concentration of glycerol, while slow and fast freezing performed better with 10% and 15% DMSO concentrations, which implies that DMSO may serve as better cryoprotectant for poultry semen freezing irrespective of freezing protocols adopted.

Soil microorganisms interacting with residue-derived allelochemicals effects on seed germination.

Despite the knowledge regarding allelopathy, known as a major ecological mechanism for biological weed control, had increased greatly, the role of soil microorganisms in that field remained controversial. The study sought to evaluate the interference potential of soil microorganisms, residues-derived allelochemicals and their interaction on seed germination and understand the variation of microbial community in allelopathic activities. Three different rice residues-derived fractions from variety PI312777 (extracts, straw fraction and fresh residue) were applied to sterile and live soils to disentangle the interference potential of soil microorganisms, residues-derived allelochemicals and their interaction concerned allelopathic activities. The results demonstrated that microbe-only and residues-only exerted onefold promotion and inhibition effects on lettuce (Lactuca sativa Linn.) seed germination, respectively, whereas, microbe-by-residues interaction showed an inhibition at the beginning, and a feeble promotion later. The 20 most dominant genera of microbes were classified into three clusters, with 13 genera in one cluster, only 1 in the second cluster and 6 in the third one. The genera in the first cluster commonly exerted negative effects on phenol content, while showed positive correlation with seed germination. Interestingly, Bacillus, clustered in the second cluster, had an opposite effect alone. The third cluster genera somehow had a weak correlation with both germination as well as the release of the allelochemicals. Overall, we incorporated molecular methodology for tracking bacterial impacts during incubation with allelochemicals, and demonstrated the mutable role of soil microbes in allelopathy. It may be potentially important for stimulating the beneficial roles of microbes for environmentally friendly weed management.

Biphasic fractionation of rice straw under mild condition in acidified 2-phenoxyethanol/water system

A novel biphasic organic solvent, 2-phenoxyethanol (EPH) was introduced to pretreat and fractionate rice straw into glucose/glucan, xylose/xylan and lignin under mild conditions. In addition, the combined severity factor (CSF) was used to evaluate the effect of pretreatment severity on the composition variation of rice straw. Under the biphasic system (0.05 M H2SO4, 70 % EPH:30 % H2O), 130 ℃ cooking rice straw 2 h, 86.48 % of cellulose retention in solid residue, 92.10 % of hemicellulose removal and 63.16 % of lignin removal were obtained. Then, the solid residue was enzymatically digested with a glucose yield of 80.94 % at 36 h, and the pure lignin (92.60 %) was recovered by simple precipitation. Based on the fractionation process, 96.69 % of glucose and glucan, 81.83 % of xylose and xylan, and 71.71 % of lignin in solid and liquid phase were recovered. Finally, the residue, especially the retrieved lignin was characterized by SEM, XRD, FTIR, HSQC and thermogravimetric analysis.

Distribution of common cocklebur and palmer amaranth seed exiting the combine for harvest weed seed control in soybean

AbstractHarvest weed seed control (HWSC) tactics are being investigated for herbicide resistance management by reducing the number of weed seeds entering the soil seedbank. Weed seed retention and the location where weed seeds exit the combine (chaff, straw, or grain) are factors influencing potential HWSC success. An experiment was conducted in 2014 and 2015 in Keiser, AR, to determine where the seeds of common cocklebur (Xanthium strumarium L.) and Palmer amaranth (Amaranthus palmeri S. Wats.) exited the combine during soybean [Glycine max (L.) Merr.] harvest. Plots within soybean production fields containing infestations of common cocklebur and Palmer amaranth were harvested with a combine and the grain, chaff (top sieve), and straw (rotor) fractions were collected. The number of seeds in each fraction was determined for both species. The grain fraction contained 6 and 13% of the total Palmer amaranth and common cocklebur seed entering the combine, with 75 and 85% of the common cocklebur and Palmer amaranth seed, respectively, in the chaff fraction. As the chaff fraction is the target for many HWSC systems (e.g., integrated Harrington Seed Destructor, chaff carts, chaff lining, and chaff tramlining), these proportions indicate the potential success of these systems. The HWSC systems that target all harvest residues (e.g. narrow windrow burning and bale direct) would potentially control high proportions of common cocklebur and Palmer amaranth seed (94 and 87% respectively) during harvest. Preventing this seed from entering the seedbank would improve weed management programs and lessen the likelihood of selecting for herbicide resistance.

Fractionation and characterization of lignin from waste rice straw: Biomass surface chemical composition analysis

Waste rice straw (RS) was fractionated to extract the lignin using alkaline (sodium hydroxide) treatment (SHT) and organic acid (Formic acid/Acetic acid) treatment (OAT) process. Rice straw fractionation by the acetic OAT and alkaline SHT methods resulted in the recovery of OAT-lignin and SHT-lignin respectively. The structural characterization of the extracted lignin fractions was done by UV–vis spectroscopy, FTIR and 1H NMR technique. Total phenolic content (TPC) present in SHT-lignin and OAT-lignin were determined to be 28.87 mg GAE/g and 24.75 mg GAE/g respectively. The DPPH radical scavenging activity 59.50% was observed in SHT-lignin and 45.74% in OAT-lignin using the DPPH test for 30 min of incubation. Surface characterization of untreated rice straw (UT-RS) and treated rice straw (SHT-RS and OAT-RS) were carried out by XRD, FTIR and SEM. X-ray photoelectron spectroscopy (XPS) survey, C1s, and O1s spectra were used to determined the surface carbon and oxygen composition changes in RS after SHT and OAT. These structural characterizations of lignin and biomass are beneficial for further processing in bio-refinery industry.

Critical changes of inorganics during combustion of herbaceous biomass displayed in its water soluble fractions

In order to clarify the key factors of problems in combustion of herbaceous biomass, soluble and insoluble fractions of corn stover, wheat straw and rice straw pre and post combustion were prepared and examined. Elemental contents, components of the samples and mass-loss/heat-effect at heating stage of the samples were measured using X-ray fluorescence (XRF), X-ray Diffraction (XRD), and simultaneous thermal analysis (STA). Supplementary STA experiments on water soluble fraction of raw biomass, mixtures of KCl, K2SO4, and ash/FeS2 were analyzed to explain some phenomena. Results show that: 1) The change of solubility from pre to post combustion varies significantly with elements. 2) Congruent melting of KCl and K2SO4 occurs at 680 °C during combustion of herbaceous biomass. 3) Changes and release of KCl is the major cause of mass loss of biomass ash at temperature below 900 °C.