Thesis (Ph. D., Biological and Agricultural Engineering)--University of Idaho, December 2007. / Major professor: Jon Van Gerpen. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (M.S.)--Rowan University, 2006 / Typescript. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.

Includes bibliographical references (p. 93-95).

Thesis (M.S.)--Oregon State University, 2005. / Printout. Includes bibliographical references (leaves 88-89). Also available on the World Wide Web.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.

Due to the numerous disadvantages associated with the use of fossil fuels, focus has been drawn on the environmentally friendly, renewable and carbon-neutral alternative, algalbased biofuels. Many microalgal species have been studied due to their ability to produce significant lipid yields which may be converted to biodiesel. In the present study three microalgal species were screened and a model organism that produced maximal lipid yields, had the greatest lipid productivity and showed potential to be used on a large scale basis, was selected. The selected species was identified, using both morphological and molecular methods, as Isochrysis galbana U4. Nitrogen (N) limitation and depletion studies showed that an internal N reservoir determines cell growth and eventual lipid accumulation in I. galbana when the external N reserves are deplete. Intracellular N depletion was associated with a decrease in the pyrenoid size and chlorophyll content, a breakdown of the chloroplast and the production of large lipid bodies which is advantageous in terms of lipid sequestration for biodiesel production. Cost reduction approaches for the mass culture of I. galbana were investigated. Factors that were proven to reduce costs, without altering the final lipid yield, included the use of urea as a N source and the supply of lower phosphorus (P) levels since this species is capable of growing optimally with as little as 0.25 ppm P. Furthermore, I. galbana cells demonstrated spontaneous flocculating abilities when cultured for prolonged periods. This is advantageous in the cost reductions of downstream harvesting processes. Both, 7 L and 16 L photobioreactors (PBR) were tested. Culture upscale resulted in the concomitant decrease in algal growth rate which was attributed to the limitations on the carbon dioxide and light supply in scaled up systems. Hence, it is suggested that multiple smaller units be used in an industrial setup. Overall, I. galbana is a promising candidate for biodiesel production, due to its ability to produce large amounts of lipid, its elevated growth rates and low P demand. The use of a two-phase PBR (The first phase being nutrient replete, promoting cell growth and division, and the second phase nutrient deplete, promoting lipid production) for the mass culture of this species in industry is recommended.

Thesis (M.S.)--University of Tennessee, Knoxville, 2009. / Title from title page screen (viewed on Oct. 23, 2009). Thesis advisor: David K. Irick. Vita. Includes bibliographical references.

No description available.

Solid basic metal oxides have been extensively studied for biodiesel production via transesterification, researches are now focused on attaining high catalytic activity and durability towards one-step alkali transesterification, as well as high stability towards high free fatty acids (FFAs) and water content in oils for simultaneous esterification and transesterification, to enable their commercialization in industry. This work encompasses the design and characterization of three mixed metal oxide systems, with a detailed evaluation of their potential application in catalyzing transesterification of camelina oil to yield biodiesel. Na0.1Ca0.9TiO3 nanorods were synthesized via a simple alkaline hydrothermal pathway with ethanol as a co-solvent. Owing to their high basic strength of 11<H_<15, 92.7% biodiesel conversion was reached at mild reaction conditions. However, the catalyst showed poor recycle performance, probably attributed to the leaching of active species during transesterification, as revealed by X-ray photoelectron spectroscopy (XPS). A new class of mesoporous Zn/MgO catalyst was synthesized by a simple alkaline hydrothermal method. Zn/MgO calcinated at 600 ℃ exhibited 88.7% biodiesel conversion at 120 ℃ with 3% w/w catalyst, 24:1 methanol to oil molar ratio for 8 h. The catalyst could be reused for five runs without significant loss of activity (≥84.0% biodiesel conversion). The excellent catalyst performance is possibly attributed to its high surface area and large mesopores. The higher surface basic sites density as compared to mesoporous MgO, as indicated by higher total basicity determined from benzoic titration and an increased lattice O2- percentage as revealed from XPS, attributing to its superior catalytic activity. A series of nano-sized MgO-ZnO catalysts with precise stoichiometry were successfully prepared by a simple EDTA complexing approach. Mg0.5Zn0.5 calcinated at 600 ℃ gave a maximum biodiesel conversion of 89.3% at 120 ℃ with 3% w/w catalyst, 24:1 methanol to oil molar ratio for 8 h. Its superior catalytic performance to MgO is mainly associated with the high basic sites density as determined from benzoic titration and XPS. The biodiesel conversion retained over 83.0% for five runs. The enhanced catalyst activity and stability might be contributed by the incorporation of Zn2+ for Mg2+ in MgO lattice and a high homogeneous distribution of MgO particles on ZnO, with the formation of Mg-O-Zn bond as evidenced by Fourier transform infrared spectroscope (FTIR) and XPS. The catalyst also demonstrated high tolerance to FFAs (10% w/w) and water (2% w/w) content, which make it desirable for direct conversion of oils with high FFAs level to biodiesel in a single-step process. Lastly, a Zn/La2O3 catalyst was synthesized by a simple hydrothermal pathway. It exhibits a higher basic strength than La2O3, as evidenced by the slightly lower O1s binding energy determined by XPS, leading to a higher catalytic activity. The enhanced catalytic activity and stability is likely contributed by the incorporation of Zn2+ for La3+ in the lattice. Using 1% w/w Zn/La2O3 as catalyst, the highest biodiesel conversion of 92.7% was obtained at 120 ℃ for 16 h with 36:1 methanol to oil molar ratio. The effective catalyst displayed a biodiesel conversion greater than 84.0% for four runs. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy