Cell-wall structural changes in wheat straw pretreated for bioethanol production

Abstract Background Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Recent results indicate that only a mild pretreatment is necessary in an industrial, economically feasible system. The Integrated Biomass Utilisation System hydrothermal pretreatment process has previously been shown to be effective in preparing wheat straw for these processes without the application of additional chemicals. In the current work, the effect of the pretreatment on the straw cell-wall matrix and its components are characterised microscopically (atomic force microscopy and scanning electron microscopy) and spectroscopically (attenuated total reflectance Fourier transform infrared spectroscopy) in order to understand this increase in digestibility. Results The hydrothermal pretreatment does not degrade the fibrillar structure of cellulose but causes profound lignin re-localisation. Results from the current work indicate that wax has been removed and hemicellulose has been partially removed. Similar changes were found in wheat straw pretreated by steam explosion. Conclusion Results indicate that hydrothermal pretreatment increases the digestibility by increasing the accessibility of the cellulose through a re-localisation of lignin and a partial removal of hemicellulose, rather than by disruption of the cell wall.</p

Examination of Combustion-Generated Smoke Particles from Biomass at Source: Relation to Atmospheric Light Absorption

The formation of carbonaceous aerosols from biomass combustion is associated with a high degree of uncertainty in global climate models. In this work, soot samples were generated from the combustion of pine wood, wheat straw and barley straw in a fixed bed stove; as well as from the combustion of biomass pyrolysis model compounds. Samples were collected on filters, which were used for the determination of Absorption Angstrom Exponent (AAE). In addition, the content and composition of elemental carbon (EC) and organic carbon (OC) were determined, and the interrelationships between these and the AAE were examined. It was found that the spectroscopic signature of samples with high ‘brown carbon’ emissions was comparable to that of many PAH and polyphenols, with AAE ranging from 1.0–1.2 for model compounds to 0.5–5.7 for biomass. In addition to the filter samples, particles were collected directly onto microscopy grids and analysed by transmission electron microscopy–electron energy loss spectroscopy (TEM-EELS) in order to determine structural characteristics. This was used to examine the impact of combustion conditions and flue gas dilution on particle structure. Smouldering phase and diluted particles were found to be less graphitic and twice as oxygenated as undiluted flaming phase particles. The results are interpreted to better understand the impact of combustion processes on soot formation from biomass combustion. Abbreviations: AAE: absorption angstrom exponent; ATN: light attenuation; AToFMS: aerosol time of flight mass spectrometer; BC: black carbon; BrC: brown carbon; C:O: carbon to oxygen ratio; CPD: cyclopentadienyl radical C5H5; DMS: differential mobility spectrometer; EC: elemental carbon; EELS: electron energy loss spectroscopy; HACA: hydrogen abstraction carbon addition; MCE: modified combustion efficiency; OA: organic aerosols; OC: organic carbon; PM: particulate matter; POM: primary (particulate)organic matter; Py-GC/MS: pyrolysis gas chromatography/mass spectrometry; sp2: amount of sp2 orbital hybridisation in atomic structure; SSA: single scattering albedo; TC: total carbon (BC+OC) or (EC+OC); TEM: transmission electron microscope; TGA: thermogravimetric analysis

Hot Compressed Water Extraction of Lignin by Using a Flow-Through Reactor

Japanese rice straw, an agricultural by-product, was utilized for the extraction of lignin by hot compressed water at temperatures of 443&nbsp;- 503 K and a pressure of 4.0 MPa using a flow-through system, a simple and environmentally friendly extraction method requiring no chemicals other than water. Under these conditions, thermal softening of the Japanese rice straw occurred, allowing the removal of lignin via depolymerization reactions. Lignin as an extraction product was analyzed using utraviolet-visible (UV-vis) spectrophotometry. Lignin recovery approached 85% when the extraction was performed at 443 and 473 K with a flow rate of 4.67 ml min-1. At a constant residence time, recovery amounts increased with increasing flow rate at each temperature. The results suggested that this process may result in an advanced plant biomass components extraction technology

Determination and Prediction of Some Soil Properties Using Partial Least Square (PLS) Calibration and Mid-Infra Red (MIR) Spectroscopy Analysis

Soil chemical, physical and biological analyses are a crucial but often expensive and time-consuming step in the characterization of soils. Rapid and accurate predictions and relatively simple methods are ideally needed for soil analysis. The objective of this study was to predict some soil properties (e.g. pH, EC, total C, total N,C/N, NH4-N, NO3-N, P, K, clay, silt, and sand and soil microbial biomass carbon) across the Wickepin farm during summer season using a Mid-Infra Red - Partial Least Square (MIR&ndash;PLS) method. The 291 soil samples were analyzed bothwith soil extraction procedure and MIR Spectrometer. Calibrations were developed between MIR spectral data and the results of soil extraction procedures. Results using the PLS-MIR showed that MIR-predicted values were almost as highly correlated to the measured value obtained by the soil extraction method of total carbon, total nitrogen and soil pH. Values for EC, NH4-N, NO3-N, C/N, P, K, clay, silt, sand, and soil microbial biomass carbon were not successfully predicted by the MIR &ndash; PLS technique. There was a tendency for these factors to correlate with the MIR predicted value, but the correlation values were very low. This study has confirmed that the MIR-PLS method can be used to predict some soil properties based on calibrations of MIR values

Straw mulch in organically grown potatoes - evaluation and optimisation for virus vector control

1. In order to evaluate effects of straw mulch applied at 2.5 – 5 t ha-1 in organically grown potatoes (Solanum tuberosum L.), 21 field experiments were conducted over five years at two locations Northern Hessen and Southern Niedersachsen, Germany). The experimental sites were characterised by temperate climate conditions (635 – 709 mm precipitation year-1; 8.1°C mean air temperature) and loamy silt soils. The main focus of the study was on aphids and the aphidtransmitted Potato virus Y (PVY). This disease is a main problem in seed potato production. In addition to virus and vectors, associated agronomic effects of straw mulch were studied. 2. Straw mulch significantly reduced the incidence of PVY. It was most effective as a protectant for young plants against PVY, thus when a high vector pressure occurred early in the year. Combined mulching and presprouting (chitting) had a synergistic effect on the reduction of PVY incidence, with mulching affecting early vectors while the chitted plants exhibited adult plant resistance earlier, thus protecting from late occurring vectors. 3. Straw mulch reduced aphid infestation on potato leaves and populations of potato-colonising aphids, but did not affect population growth rates. Scaling up the area mulched stepwise from 100 m² to 900m² consistently kept aphid infestation at reduced levels. 4. In a small scale experiment, straw mulch resulted in a reduction of the number of winged aphids landing in green water traps, compared to traps placed on bare soil; this effect was significant with amounts of 200 g straw m-2 and ≥ 400 g m-2, but increasing the straw quantity beyond 200 g m-2 did not cause a further significant aphid reduction. 5. In two further field experiments in 2003, aphid landing in green water traps placed on various backgrounds was tested, including differently coloured plastic sheets, straw and uncovered soil as backgrounds. Aphid catches were highest in traps on uncovered background (soil), and lowest in traps on white or silver backgrounds. For seven aphid species there was a negative correlation between UV-reflectance (320 – 400 nm) of backgrounds and log(N+1)-transformed number of individuals. However, the effect of straw mulch (reduced aphid catches with straw compared to soil), could not be attributed to differences in UV-reflectance, as the UV reflectance was almost identical in soil and straw. 6. Tuber yield and tuber size distribution were not influenced significantly or in a uniform direction by straw mulch application in eleven field experiments, conducted over four years. 7. There was no consistent effect of straw mulch on weed parameters as number of weeds, weed cover and above-ground biomass of weeds. 8. The fact that yield and weed development were not significantly affected by straw mulch is largely attributed to the relatively low amounts of straw applied, which were chosen for the primary purpose of vector control. 9. The risk of undesirable post harvest N-leaching was reduced by straw mulch due to the immobilisation of nitrate-N after harvest at 6.8 – 7.0 kg N t-1 straw in two experiments (18 – 34 kg NO3–N ha-1). 10. Soil erosion was greatly reduced (by >97 %) in a rain simulation experiment on a 8 % sloping potato field with 20 % crop cover. 11. Severity of late blight (Phytophthora infestans) was estimated in five of the experiments at 3 – 7 dates per experiment. Straw mulch had no significant effect on late blight severity, measured as relative area under the disease progress curve, in any of the experiments, but a trend reducing late blight by straw mulch was observed in all five experiments. 12. Infestation with sclerotia of black scurf (Rhizoctonia solani) on harvested tubers, assessed on 100 – 220 tubers per plot, was not influenced consistently by straw mulch, with effects being nonsignificant in eight out of nine experiments. 13. Effects of straw mulch on microclimate, measured in one field experiment, were dependent on the time of the day, with the air in mulched plots being moister and cooler at night and dryer and warmer during the day. This effect was less marked in the period 4 – 6 weeks after mulching than in the fortnight directly after mulching. 14. Prospects and constraints of straw mulch application in organic potato production are discussed and parameters for optimisation are suggested

Determination and Prediction of Some Soil Properties using Partial Least Square (PLS) Calibration and Mid-Infra Red (MIR) Spectroscopy Analysis

Soil chemical, physical and biological analyses are a crucial but often expensive and time-consuming step in the characterization of soils. Rapid and accurate predictions and relatively simple methods are ideally needed for soil analysis. The objective of this study was to predict some soil properties (e.g. pH, EC, total C, total N,C/N, NH4-N, NO3-N, P, K, clay, silt, and sand and soil microbial biomass carbon) across the Wickepin farm during summer season using a Mid-Infra Red - Partial Least Square (MIR–PLS) method. The 291 soil samples were analyzed bothwith soil extraction procedure and MIR Spectrometer. Calibrations were developed between MIR spectral data and the results of soil extraction procedures. Results using the PLS-MIR showed that MIR-predicted values were almost as highly correlated to the measured value obtained by the soil extraction method of total carbon, total nitrogen and soil pH. Values for EC, NH4-N, NO3-N, C/N, P, K, clay, silt, sand, and soil microbial biomass carbon were not successfully predicted by the MIR – PLS technique. There was a tendency for these factors to correlate with the MIR predicted value, but the correlation values were very low. This study has confirmed that the MIR-PLS method can be used to predict some soil properties based on calibrations of MIR values.Keywords: MIR-Partial Least Square, MIR-Spectroscopy, soil propertie

Characterization of Naturally Derived Polymer by Oxidative, Thermal, and Spectrometric Methods

Extensive use of fossil fuel for different purposes has resulted in significant depletion of it at an alarming rate. Therefore, a potential and sustainable alternative source are badly needed at this moment. Nowadays, lignocellulose biomass is appealing to much interest by the researchers because of its potential nature as a renewable carbon source. It is the most abundant renewable source which is composed of cellulose, hemicellulose, and lignin. Among them, lignin is considered the 2nd most abundantly natural polymer after cellulose which comprises 10-30 % of biomass depending on the source and the environment. Lignin is a three-dimensional cross-linked organic polymer, composed of three different phenylpropanoid units such as coniferyl, sinapyl, and pcoumaryl alcohols. Being a renewable and polyaromatic by nature, lignin is being considered as a potential source of a wide range of chemicals and renewable energy. But it is very important to understand the comprehensive structure of lignin before convert into value-added products. Therefore, our main aim is to characterize the naturally derived lignin by thermal, spectrometric, oxidative, and chromatographic techniques to understand the comprehensive structure and macromolecular features of lignin. To accomplish the goal, the objectives of this work are: 1. Optimize the processing conditions for the extraction of lignin from the non-wood source. 2. To investigate the thermal stability and functional groups of lignin and its residue by thermal and spectrometric methods. 3. To study the molecular weight distribution, and monomeric structure of lignin and its residue by chromatography. 4. Oxidative degradation of lignin into monomers and to optimize the reaction conditions for conversion. In chapter II, thermal behaviors of lignin and its residue after catalytic hydrodeoxygenation reaction were characterized by TGA and DSC. TGA results indicated that both lignin and its residue showed variable weight loss in different temperature ranges, different percentages of residual carbon, and different DTGmax of the sample. Results showed that the weight loss of residue was lower than the lignin throughout different temperature ranges. But a higher percentage of residual carbon (45.85 %) was observed for residue than lignin (25.89 %). On the other hand, the maximum rate of weight loss (DTGmax) for residue was observed at a lower temperature at 420 °C than lignin at 480 °C. DSC results showed a lower melting point for residue(150.48 °C) than lignin (174.40 °C). Moreover, the lignin-residue decomposed at 370 °C, whereas no visible change was observed in lignin around this temperature. So, DSC and TGA analysis revealed that lignin residue was thermally less stable compared to lignin. Additionally, lower melting point with higher residual carbon for residue showed that both thermally stable and unstable compounds were produced during the hydrodeoxygenation reaction. In chapter III, chemical structure, functional groups, and molecular weight of lignin and residue were investigated by FTIR, NMR, and GPC analysis. FTIR study, showed both lignin and residue contain the same functional group, and no further new band was noticed, which suggests residue still contains unreacted lignin or smaller breakdown products with similar chemical properties of lignin. NMR analysis also showed the same chemical functional group present in both lignin and residue. But the quantitative study of NMR showed a different amount of the functional groups. It was shown that lignin is higher in aromatic proton where the residue is higher in the aliphatic proton. Results also showed, aliphatic/aromatic ratio of the residue is 3 times greater than the lignin. The higher aliphatic/aromatic ratio of residue demonstrated that the significant number of aromatic moieties of the lignin have gone with the reaction mixture leaving the aliphatic moiety in the residue. On the other hand, GPC analysis found three distinct peaks for lignin and two for residue. The greater molecular weight distribution and polydispersity were observed which indicated the formation of C-C bonds during the catalytic reaction. The study showed that this kind of bond formation is related to the guaiacol units which are connected to each other at elevated temperature. In chapter IV, lignin and its residue were depolymerized by cupric oxide oxidation and monomeric products were identified and quantified by GC-MS analysis. A chromatographic study showed that lignin produced four monomers and residue produced two monomers, respectively where all of them are characterized as a G moiety. Among the phenolic monomers, vanillin was the major product for both samples. Additionally, the results showed residue contains less amount of vanillin and acetovanillone than lignin and no peaks for guaiacol and homovanillic acid. Oxidative depolymerization of lignin was also carried out at different temperatures and times to optimize the reaction conditions for better yield. The chromatographic study showed four monomers produced in each condition. Among them, vanillin was found as a major product and production of vanillin increased with the increase of both temperatures and times. The production of guaiacol and acetovanillone increased when the temperature reached 150 °C and time at 2 hours then slightly decreased with the increase of both temperature and time. But the production of homovanillic acid significantly decreased when the temperature reached 175 °C but slightly decreased when time reached 2.5 hours. Therefore, our oxidative study found 150 °C and 2.5 hours as an optimization conditions for the better production of phenolic monomers from lignin. In chapter V, lignin was extracted from wheat straw using an accelerated solvent extraction technique. To optimize the extraction conditions, extraction was carried at three different temperatures such as 140 °C, 170 °C, and 200 °C and two different acidic conditions 0.05% and 0.1% for 60 minutes. Then the extracted lignin was characterized by TGA, FTIR, and subcritical water. The study showed that extraction of lignin increased from 13.89 % to 28.69 % when the temperatures increase from 140 °C to 200 °C. But acid concentration showed very little impact on extraction of lignin. It was shown, extraction of lignin increased slightly with the increases of acid concentration at a specific temperature. On the other hand, characterization of lignin with TGA, FT-IR, and liquefaction showed the similar result with the commercial lignin, indicated lignin was successfully extracted from wheat straw. Liquefaction of lignin followed by GC-MS analysis showed 9 phenolic monomeric products with 86% total relative amount

Estimating global warming potential for agricultural landscapes with minimal field data and cost

Greenhouse gas (GHG) emissions from agriculture comprise 10-12% of anthropocentric global emissions; and 76% of the agricultural emissions are generated in the developing world. Landscape GHG accounting is an effective way to efficiently develop baseline emissions and appropriate mitigation approaches. In a 9,736-hectare case study area dominated by rice and wheat in the Karnal district of Haryana state, India, the authors used a low-cost landscape agricultural GHG accounting method with limited fieldwork, remote sensing, and biogeochemical modeling. We used the DeNitrification-DeComposition (DNDC) model software to simulate crop growth and carbon and nitrogen cycling to estimate net GHG emissions, with information based on the mapping of cropping patterns over time using multi- resolution and multi-temporal optical remote sensing imagery. We estimated a mean net emission of 78,620 tCO2e/yr (tons of carbon dioxide equivalents per year) with a 95% confidence interval of 51,212-106,028 tCO2e/yr based on uncertainties in our crop mapping and soil data. A modeling sensitivity analysis showed soil clay fraction, soil organic carbon fraction, soil density, and nitrogen amendments to be among the most sensitive factors, and therefore critical to capture in field surveys. We recommend a multi-phase approach to increase efficiency and reduce cost in GHG accounting. Field campaigns and aspects of remote sensing image characteristics can be optimized for targeted landscapes through solid background research. An appropriate modeling approach can be selected based on crop and soil characteristics. Soil data in developing world landscapes remain a significant source of uncertainty for studies like these and should remain a key research and data development effort