| dc.description.abstract | Microemulsions are thermodynamically stable dispersions of oil and water stabilized by a film of surfactants and/or co-surfactants. They have numerous applications in food, oilseed extraction, drug and cosmetic delivery, enhanced oil recovery, biofuels, etc. Microemulsion formation of vegetable oils at ambient conditions (temperature and pressure) and without the addition of co-oil and/or alcohols is challenging at best. Undesirable phases, such as macroemulsions, liquid crystals and sponge phases, are often encountered when formulating these microemulsions. The goal of this dissertation is to formulate vegetable oil microemulsions using a novel class of surfactants, called extended-surfactants combining with hydrophilic/hydrophobic linker system, and to explore their uses in oilseed extraction and bio-renewable fuel applications. Extended-surfactants are a relatively new type of surfactant with propoxylate (PO) and/or ethoxylate (EO) groups inserted between the hydrophilic head and the hydrophobic alkyl chain of the surfactant molecule. This unique structure of extended-surfactants enables them to produce ultralow interfacial tension with vegetable oils at ambient condition. Environmentally friendly vegetable oil microemulsions were successfully formed without the addition of co-oil/alcohol at ambient temperature. These microemulsions are particularly useful in food, drug and cosmetic applications. Owing to the ultralow interfacial tension reduction between the vegetable oil and aqueous extended-surfactant solution at relatively low surfactant concentration, we have demonstrated that the aqueous extended-surfactant-based method is a viable alternative for vegetable oil extraction as in batch study. The oil quality produced from the aqueous extended-surfactant based method was found to be comparable or even superior to that obtained from hexane-based extraction. Next, we have designed and investigated a semi-continuous pilot-scale study of the aqueous extended-surfactant-based method for vegetable oil extraction. The total oil recovery after two extraction stages was approaching the result obtained from the batch study; however, the free oil recovery was lower. We have shown that the aqueous surfactant based method for oilseed extraction is superior to that of aqueous extraction method and enzyme-assisted extraction method. The last part of the dissertation demonstrated the use of reverse micellar microemulsions of vegetable oil/diesel blend as an alternative to diesel fuel. With appropriate surfactant and co-surfactant systems, we were able to formulate canola and algae/diesel blend microemulsion fuels with fuel properties such as viscosities, cloud points and pour points that satisfy the ASTM standards. The global CO pollutant and radiation emissions of all formulated microemulsion fuels were superior to DF and biodiesel. NOx emissions were lower in the blend containing no nitrate additives, but were higher than DF in the presence of nitrate additives. Thus, these results show that microemulsification is a viable technology for producing biofuels without chemical reactions and that fuel properties can be adjusted via formulation variables. | |
