In Situ Production Of Biodiesel And Synthesis Of Polyol Ester As A Biolubricant Base Oil From Microbial Lipids

Microbial lipids have been intensively investigated during past decades as a promising candidate of biodiesel feedstock, owing to the high-lipid yielding capacity, rapid growth properties, environmental-friendly nature. However, microbial biodiesel production has been still limited due to the technical and economic obstacles associated with oleaginous microorganisms effective large-scale cultivation, harvesting, dewatering and lipid extraction and the difficult transesterification into biodiesel. In this study, there is a focus on microbial lipids analysis and transformation.Firstly, three lipid extraction methods of Bligh & Dyer, Soxhlet extraction and Solvent extraction were applied on Autotrophy C.vulgaris, Heterotrophy C.vulgaris and R.glutinis biomass to evaluate their effects on lipid yield and lipid composition. It had the highest lipid yields of 23.25%, 24.39% and 29.02% on Autotrophy C.vulgaris, Heterotrophy C.vulgaris and R.glutinis biomass, respectively. The lipid profiling analysis showed that palmitic, linoleic, and a-linolenic acids were the major fatty acids in the algal lipids, and palmitic and oleic acids were the major fatty acids in the yeast lipids. All three extractions on algae biomass were linked to higher glycolipids and phospholipids, while the extractions on yeast biomass were related to higher glycolipids.Then a in-situ (direct) transesterification process using 75% ethanol and co-solvent was studied to reduce the energy consumption of lipid extraction process and improve the conversion yield of the microalgae biodiesel. The addition of a certain amount of co-solvent (n-hexane is most preferable) was required for the in-situ transesterification of microalgae biomass. With the optimal reaction condition of n-hexane to 75% ethanol volume ratio 1:2, mixed solvent dosage 6.0 mL, reaction temperature 90?, reaction time 2.0 h and catalyst volume 0.6 mL, the in-situ transesterification process of microalgal biomass resulted in a high conversion yield up to 90.02±0.55 wt.%. Response surface methodology (RSM) based on Box-Behnken Design (BBD) was employed to design the experiments and analyze the effect of significant process variables on the conversion yield. The in-situ transesterification process resulted in a high conversion yield up to 90.24± 0.65 wt.%.In the final installment of this work, the biolubricants was synthesized from fatty acid ethyl esters (FAEE), including ethyl oleate and ethyl palmitate, by transesterification with trimethylolpropane (TMP) using lithium amide as catalyst. Model transesterification reactions were performed with FAEE to optimize the reaction conditions to obtain maximum yield of trimethylolpropane fatty acid triester (TFATE). With the optimal reaction condition of catalyst dosage 1.0%(w/w-FAEE), reaction time 150 min, reaction temperature 130?, TMP to FAEE molar ratio 1:4, FAEE-derived biolubricant with TFATE composition of 84.13±2.31% was obtained. Under similar reaction conditions, yeast biodiesel-derived biolubricant comprising of 78.13±5.50% of TFATE was obtained...