Thesis (Ph.D.)--University of Minnesota, 2007. / Advisers: Roger Ruan, Jun Zhu. Includes bibliographical references.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 77-81).

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 128-133). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 128-133). Also available on the Internet.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1994. / Typescript. Bibliography: leaves 141-148. Also available online.

Thesis (M.S.)--Baylor University, 2009. / Includes bibliographical references (p. 54-61).

Thesis ( MTech (Business Administration))--Cape Peninsula University of Technology, 2016. / Capital investment in bioethanol production requires sound economic feasibility studies. This study investigated the economic feasibility of using maize as a feedstock to produce bioethanol in South Africa. There is a huge opportunity to use dedicated underutilised arable land to grow maize which can be used for both consumption and bioethanol production. The study used 200 000 ton/year of maize that could have been exported to SADC countries to size a plant that produces 80 million litres per year of bioethanol. An advanced bioethanol processing technology that separates the fibre/bran which is burnt in a steam boiler to produce process steam was selected owing to advantages such as low energy consumption and capital expenditure on fermentation and distillation equipment. This study employed a combination of qualitative and quantitative methods to gather data. The findings from a qualitative instrument indicated that a majority of respondents were in favour of the decision of excluding maize made by the South African government. Putting security of food at risk and uncertainty in the profitability of a maize-fed bioethanol plant in the South African context, were two of the primary reasons the respondents opted for an explicit exclusion of maize as a feedstock. Findings from quantitative analysis revealed that the profitability of the bioethanol plant was largely influenced by the prices of feedstock and bioethanol. The 2016 fiscal year indicated the worst case scenario in terms of economic viability of the bioethanol. The astronomically high price of maize due to drought (R5000/ton) rendered the project unprofitable as all of the economic indicators were negative. In the same marketing year, however, the trade balance of maize was positive, indicating a surplus. The study recommended that all of the surplus maize should be exported because it is not economically viable to build a bioethanol plant. The 2011 fiscal year indicated the best case scenario in terms of the economics of the project. This was due to the decrease in price of maize (R1726/ton) and a slight increase in the price of bioethanol. All of the economic indicators were positive, suggesting the benefits of investing in bioethanol production. It was recommended that under normal conditions of maize production in South Africa, a bioethanol plant can be operated simultaneous to maize exportation to other countries without compromising food security, because a maize-fed bioethanol plant uses only a small proportion of maize (14.3%) from the total volume of maize that is exported. Furthermore, it generates more revenue (99.9%) compared to the maize export revenue. It was recommended that sensitivity analysis should be conducted in a holistic manner whereby all variables in the economic model must be adjusted to assess the impact of each on the overall project profitability.

Ph.D. (Chemistry) / This study presents work on the preparation, characterisation and application of agricultural waste residue, maize tassel in the production of activated carbon (AC) using both physical and chemical methods of activation in their production. The activated carbon produced from maize tassel (MTAC) or steam-produced activated carbon (STAC) were later added as a filler – together with beta-cyclodextrin (β-CD), and raw tassel (RT) – in the production of polyurethane composite adsorbent (PUCAD) material for the removal of selected inorganic (such as Cd2+, Cr3+, Pb2+) and organic pollutants (phenolic compound - bisphenol A (BPA), ortho-nitrophenol (O-NTP), para-chlorophenol (PCP), polychlorinated biphenyl (PCB), and methylene blue (MB) as adsorbate/analytes from aqueous medium. Both batch and solid-phase extraction adsorption methods (SPE), were used for separation and preconcentration. The investigations included reactivity using Fourier transform infrared (FT-IR) spectroscopy, surface morphology analysis using scanning electron microscopy (SEM), thermal stability using thermogravimetric analysis (TGA), heat flow using differential scanning calorimetry (DSC), and crystallinity using X-ray diffraction (XRD) coupled with energy dispersive X-ray spectrometry (EDX). The FT-IR analysis revealed that there was interaction between the polymeric material and all the fillers. The hydrogen bonding and N-H group interaction between all the materials and the polyurethane polymer composite (PCAD) showed compatibility between the polymeric materials and the fillers.

A microbiological and economic study of methane production from dairy cattle waste was performed. The profit potential of producing methane and other vendable products from dairy cattle wastes was studied using a computerized cost model. The unit gas cost ($/cu. ft. methane) was determined for refractory volatile solids (VS) concentrations between 52% and 28% (W/W). Reaction rate constants (RKO) between 5.92 x 109 and 1.24 x 1011 were used. Retention time (RT) was varied between 1 and 10 days. Total solids (TS) concentration was varied between 8% and 14%. Analyses were performed with and without a fertilizer plant option for upgrading digester effluent solids. Unit gas cost (UGC) decreased as RKO increased and as the refractory VS concentration decreased when determined without the fertilizer option. UGC decreased at short retention times as RKO increased when the fertilizer option was included. The unit gas costs were always above $8.00 per M. cu. ft. CH4 without a fertilizer plant, and were consistently lower than the current intrastate market price of $3.18 per M. cu. ft. CH4 when a fertilizer plant was incorporated into the system. Microbiological studies were conducted using a multistage multistream digester. The design consisted of a 1,700 liter central digester with a working volume of 1,200 liters and 10, 50 liter satellite digesters with a working volume of 40 liters each. The digester design allowed for the automatic addition of substrate to the central digester once per hour and three times per hour to the satellites. The digester was operated at 55┬░C and 10% TS with a 6 day RT in the central digester and 2 days RT in the satellites. Manure from a commercial dairy was utilized for substrate. Methane production was directly related to the type of cattle feed ration. It ranged between 1.27 and 0.3 liters CH4 per liter of reactor fluid per day at a 6 day RT. Alkalinity, volatile fatty acids (VFA) and ammonia concentrations were related to methane production. VFA concentrations were lower and methane production slightly higher in the satellite digesters. Analysis of the digester effluent for fertilizer value was investigated by drying for 10 days on a as and drying bed at an initial depth of 10 cm. Total nitrogen, phosphorous (as P2O5) and potassium (as K2O) concentrations were: 1.8%, 1.1% and 7.2% for undigested manure; 4.5%, 2.3%, and 9.1% for 6 day RT effluent; 2.0%, 1.1% and 7.5% for 8 day RT effluent. Our economic studies indicate that digester operating conditions should include a 3-5 day RT, 10-12% TS, minimal changes in feed ration and recovery of solids for upgrading to fertilizer.

Submitted in fulfillment of the requirements of the degree of Doctor of Philosophy in Chemistry, Durban University of Technology. Durban, South Africa, 2015. / Over decades synthetic composites have become an indispensable part of our lives with their various applications such as packaging, sporting equipment, agriculture, consumer products, medical applications, building materials, automotive industry, and aerospace materials among others. Although these polymers have the desired properties for the above applications, they are invariably costly. Furthermore, they cannot be easily disposed of at the end of their useful lives and simply pile up and cause significant damage to the environment. However, the dwindling supply of fossil fuel, increased oil prices, together with the growing public concern of greenhouse gas emissions and global warming, has forced scientists to search for new development of sustainable materials from renewable resources. Hence in recent years, there is an increased interest in biocomposite manufacturing with natural resources as environmental issues are addressed. The research work presented in this dissertation is to the best of the author’s knowledge a world-first overall investigation pertaining to the concept of synthesizing a banana sap based bio-resin (BSM) reinforced with banana fibres. In this work the chemical composition of banana sap was determined to investigate the chemical reactions taking place in the resin formulation. BSM was synthesized, characterized and proposed as a potential bio-resin to be used in the biocomposite manufacture for non-functional motor vehicle components. BSM, a hybrid bio-resin was synthesized with equimolar quantities of maleic anhydride and propylene glycol and 50% banana sap. A control resin without the banana sap was also synthesized for comparison purposes. It was proposed that the presence of sugars, esters and pthalates from the sap, determined by HPLC and GC-MS, contributed to the cross-linking of the polymer chain. The acid value and viscosity of BSM were determined and found to be within specification of an industry resin. The molecular weights of the BSM and control resins were 2179 and 2114 units respectively. These were within the required molecular weight of unsaturated polyester resins. The gel and cures times of the BSM were 60% lower than the control resin suggesting that the banana sap behaved as an accelerator for the curing process. The lower cure time meant that using the banana sap in the formulation was cost effective and time saving. The thermal properties of BSM showed improved degradation temperatures and degree of crystallinity compared to the control resin. A parametric study showed that increasing banana sap concentration in the resin formulation led to increased tensile and flexural properties with 50% being the optimum amount of sap to be added to the formulation. The synthesized bio-resin and control resin were applied to biocomposites and characterized in terms of physical, thermal, mechanical, morphological, chemical and biodegradable properties. Mechanical tests indicated a 15 % increase in tensile strength, 12 % improvement in tensile modulus and a 25 % improvement in the flexural modulus, when compared to structures produced without banana sap. Natural fibres present the challenge of poor adhesion to the matrix. Chemical treatment of the banana fibre was done to improve on the compatibility of resin to fibre. Fibre pull-out showed that treated fibres had a better bond than the untreated fibre. Parametric studies were also done to evaluate the effect of fortifying the BSM resin with nanoclay. A 5% clay loading resulted in a 24% increase in tensile strength and 28% increase in flexural properties. Finally biodegradation studies of the BSM bio-resin, BSM biocomposite, control resin and control composite were investigated and compared to a positive reference, cellulose. Results showed that over a period of 55 days the BSM biocomposite showed 17.6% biodegradation compared to 8% with the control composite. No difference in biodegradation between the BSM bio-resin and the control resin was recorded. BSM biocomposite was proposed as a potential replacement to synthetic composites that contribute to the environmental landfill problems. The main contribution of this research is the use of the reinforcement and matrix from the same natural source. An enriched understanding of the synthesis, characterization and performance of the banana sap based bio-resin and biocomposite for the use of non-functional motor vehicle components is the key outcome of this investigation.