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Mechanical properties of corn cobs.Anazodo, Uche Godwin Nzuko̥. January 1980 (has links)
Theoretical equations were developed for calculating the apparent elastic modulus and the strength of corn cob under quasi-static radial compression and simple bending. An empirical equation was derived for calculating its modulus of toughness. / Experimental justification was provided for the application of the Hertz linear elastic contact theory in determining cob mechanical properties in radial compression, since the cob is a composite of three inelastic materials. / In simple bending, the basic flexure formula was modified to account for the composite and tapered structure of the cob. / The relative contributions of the macro-structural components of the corn cob to its mechanical properties were determined. / Cob mechanical properties were found to be significantly affected by corn variety, harvest date and moisture content, but not by loading rate. Further experimental investigations showed that the cob mechanical properties were much dependent on fertilizer type and application rate but less dependent on soil type and condition.
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Mechanical properties of corn cobs.Anazodo, Uche Godwin Nzuko̥ January 1980 (has links)
No description available.
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Analysis of a feedback control system for a fluidized bed corncob combustor /Schonauer, Sylvia L. January 1900 (has links)
Thesis (M.S.)--Ohio State University, 1985. / Includes bibliographical references (leaves 93-95). Available online via OhioLINK's ETD Center
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Hygroscopic properties of corncobs and their application for small-scale, on-farm grain conditioningMoncada, Luis Fernando. January 1978 (has links)
Call number: LD2668 .T4 1978 M65 / Master of Science
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Optimization and kinetics study of solvent pretreatment of South African corn cob for succinic acid productionMudzanani, Khuthadzo Edna January 2018 (has links)
A dissertation submitted to the Faculty of Engineering and the Built
Environment, University of the Witwatersrand, Johannesburg, in fulfilment of
the requirements for the degree of Master of Science in Engineering.
October 2017 / Increasing concerns over environmental and geo-political issues on resources’ sustainability
have driven the industries to shift their efforts to produce chemicals from renewable biomass.
Amongst the lignocellulosic biomass, corncob contains cellulose, hemicellulose and lignin
that are built in a compact structure which makes it difficult to access. Pre-treatment is then
applied to make the content to be accessible to enzymatic hydrolysis which breaks down the
polysaccharides to monomers. The sugar monomers can be converted to a wide range of bioproducts
such as biofuels and bio-chemicals. The objective of the study was to determine,
evaluate and optimize the best solvent system to pre-treat corn cob. In addition, the study
evaluated the effect of pre-treatment parameters on the yield of cellulose and hemicellulose
and attempt to develop a kinetic model to explain the dissolution.
Lithium perchlorate, zinc chloride, phosphoric acid, sulphuric acid and sodium hydroxide
were used during the pre-treatment, which was carried out at 70-80 ° C for 6 hours.
Characterization of pre-treated samples showed a significant change in structure after pretreatment
indicating disruption in cell wall of the lignocellulosic material. FTIR revealed a
reduction in phenolic group; indicating that the lignin content has been reduced. The XRD
patterns show that crystallinity was considerably reduced; this was shown by an increase in
calculated crystallinity index (CrI) after LiClO4, ZnCl2, H3PO4 and NaOH pre-treatment. The
CrI of raw corncob (CrI= 32.7%) increased to 46.2 %, 42.3 %, 55.6 % and 53.4 % of LiClO4,
ZnCl2, H3PO4 and NaOH, respectively. The crystallinity index increased for pre-treated
material, indicating that the amorphous cellulose is dissolved in the liquor, as well as lignin
and hemicellulose removal
This study has shown that LiClO4.2H2O pretreatment agent is an efficient solvent system to
pretreat corncob which consecutively increase the accessibility of cellulose and hemicellulose
from the solid fractions. The accessibility was confirmed by an ease hydrolysis of cellulose &
hemicellulose to glucose & xylose respectively. An increase of nearly four times compared to
the untreated corncob. The effect of reaction operating parameters i.e. Reaction time,
temperature and solvent concentration was carried out and then optimized by response
surface methodology (RSM) using Minitab 16. The target was to maximize the yield of
cellulose and hemicellulose. It was discovered that the increase in temperature and reaction
time increase the accessibility of cellulose and hemicellulose until an equilibrium is reached
at 3 & half hours and 176 °c. The pretreatment solvent concentration was discovered to have
an effect on the accessibility but not as much as temperature and time. The best pretreatment
conditions to obtain high polysaccharides conversions to monomers were at 176°c for 3.5
hours using LiClO4.2H2O for 10 g of corncob.
The results obtained from RSM were used to evaluate the temperatures profile, kinetic model
for the corncob pretreatment as a function of temperature. The kinetics of pretreatment were
studied by the amount of glucose, xylose and the lignin removed from the pretreated solids.
The kinetic model of lignin removal and sugars accessibility was identified as a first-order
reaction corresponding to the bulk phase for pretreatment time up to 24 hours. The rate
constant results show that the kinetic rate increased with temperature. The activation energy
for glucose, xylose and lignin were calculated to be 15.0 kJ/mol, 14.2 kJ/mol and 36.54
kJ/mol, respectively. / MT 2018
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Synthetic studies on the spiroacetal moiety of Stenocarpin, a metabolite of Diplodia maydis /Weldegebriel, Kibrom Asmerom. January 2003 (has links)
Thesis (M.Sc.(Biochemistry))--University of Pretoria, 2003. / Includes summary. Also available online.
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Performance of a tangential feed threshing cylinder as affected by corn cob break-up and concave design parameters.Wall, Gavin Lindsay. January 1981 (has links)
A laboratory threshing unit was constructed utilising a standard tangential feed ("conventional") combine cylinder, concave, beater and transition grate. This unit was used to study the phenomenon of corn cob break-up and its effect on the performance of the threshing unit. It was found that the degree of corn cob break-up was affected by cylinder peripheral speed, cylinder-concave clearance and hybrid cultivar. Within the hybrid cultivars used, increased cob break-up was associated with decreased shelling efficiency and concave separation efficiency. / The possibility of reducing kernel damage and increasing concave separation efficiency by changing some of the concave design parameters was investigated. A mathematical model of the tangential feed threshing unit was developed and used to investigate the effect of the concave design parameters. Experimental data indicated that kernel damage may be reduced by at least 24 per cent and concave separation efficiency increased by at least 38 per cent.
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"Nanoporous carbon from corn cobs and its application"Shah, Parag S. January 2007 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Mar. 19, 2009). Vita. Includes bibliographical references.
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Development of a Non-Derivatizing Solvent System for the Pretreatment of South AfricanCorn CobEjekwu, Olayile January 2019 (has links)
A dissertation submitted to the Faculty of Engineering and the Built Environment,
University of the Witwatersrand, Johannesburg, in fulfilment of the requirements
for the Degree of Master of Science in Engineering.
March 2019 / Depleting fossil fuels and the increasing energy demand has necessitated the move to
alternative renewable forms of energy. Lignocellulosic biomass is a renewable and
sustainable source for highly valuable bio-based chemicals and material production in a
biorefinery system. The effective fractionation of the main components of lignocellulosic
biomass (cellulose, hemicellulose and lignin) into usable forms is a crucial step in unlocking an economically viable, high-value product producing biorefinery. The main concern associated with the conversion of lignocellulose is overcoming biomass recalcitrance using pretreatment while still maintaining a green, cost-effective and energy efficient process. Over the last decade, molten hydrate salts have been used for isolated cellulose dissolution, however very few studies have been done to check their ability in lignocellulosic biomass pretreatment.
The aim of the study was to compare seven molten hydrate salt solvent systems including
unary, binary and ternary mixtures of ZnCl2.4H2O, LiClO4.3H2O and Urea for the effective pretreatment of corncob in terms of physicochemical properties and pretreatment efficiencies and to optimise these efficiencies. The molten salt hydrate pretreatment systems used in this study are aimed at fractionating the corn cobs biomass into a solid fraction which mostly contains cellulose and lignin as the major components, while the liquid fraction contains hemicellulose as the main component.
The pretreatment experiments were carried out at 70 for 60 minutes at a biomass: solvent
ratio of 1:10. Physicochemical change after pretreatment was checked by FTIR, XRD and
SEM. The most efficient solvent mixture was identified by gravimetric analysis for its ability
to fractionate the biomass into a cellulose and lignin rich solid fraction and a hemicelluloserich liquid fraction. The effect of solvent pretreatment operating variables (temperature, time and solvent concentration) was investigated to maximize cellulose recovery, hemicellulose recovery in the liquid fraction and lignin recovery from the biomass by response surface methodology (RSM) approach using a central composite design (CCD).
Physicochemical analysis showed a decrease in crystallinity and an increase in surface area after the pretreatment in all the MHS solvents tested. This work has successfully shown the use of ZnCl2.4H2O/ Urea, to pre-treat and fractionate corn cob with high recovery of cellulose (100%), low recovery of hemicellulose (42%) and lignin (44%) when compared to the other proposed systems. Through the RSM approach, optimum pretreatment conditions obtained
Abstract were: 90 min, 120 oC and concentration of 71.32%/28.68 (w/w) ZnCl2.4H2O/ Urea. At these conditions, the predicted recovery for cellulose, hemicellulose and lignin 99.03%, 27.18% and 72.43% respectively with a desirability of 0.902. The actual recovery was 91%, 29% and 68% for cellulose, hemicellulose and lignin respectively at the same conditions. For a better understanding of the dissolution kinetics and thermodynamics of cellulose, hemicellulose and lignin dissolution in ZnCl2.4H2O/ Urea solvent system, a kinetic study was carried out. The results reveal the dissolution to be a 1st order kinetics and the obtained activation energy for cellulose, hemicellulose and lignin dissolution were 14.10 kJ.mol-1, 11.29 kJ.mol-1 and 7.606 kJ.mol-1 ,respectively. that the dissolution process for all three components are endothermic and endergonic. The -0.190; -0.195 kJ.mol-1) showed that the process of dissolution of hemicellulose occurred more rapidly and produced more stable products. It was concluded that ZnCl2.4H2O/ Urea pretreatment provided a potential way to fractionate lignocellulosic biomass which can improve the effective utilization of all feedstock fractions. / E.K. 2020
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Performance of a tangential feed threshing cylinder as affected by corn cob break-up and concave design parameters.Wall, Gavin Lindsay. January 1981 (has links)
No description available.
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