**7. Acknowledgement**

314 Biodiesel – Feedstocks and Processing Technologies

For a practical and economic feasible transesterification process, it is necessary to limit the reaction time at a certain period. Longer reaction time could also permit reversible transesterification reaction to occur, which eventually could reduce the yield of fatty acid alkyl esters. Thus, optimization of reaction time is also necessary. In this study, the reaction time was varied from 4 min, 6min and 8min. It was observed that the highest ME conversion (96%) was obtained for cottonseed oil at 6min reaction time. Whereas for heterogeneous catalyst, reaction times of 0.5,1, 1.5, 3, 3.5 and 4 hrs using catalyst Amberlyst-15 for Methanol to oil molar ratio 6:1, Reaction temperature of 60oC, Catalyst loading of 3wt.% were used and the highest ME conversion (85%) was obtained for cottonseed oil after 1.5 hrs reaction

The catalyst plays an important role in transesterification reaction. The type and quantity of catalyst usually depend upon the quality of feed stock and method applied for transesterification. Three values of catalyst loadings of 1, 1.5 and 2 wt% KOH were used for Methanol to oil molar ratio 6:1 at 60oC .The highest ME conversion (96%) was observed for

Similarly the second homogeneous catalyst NaOH also resulted in the same conversion for the same experimental conditions. Whereas the heterogeneous catalyst Amberlyst-15 was used in three catalyst loadings of 3, 4.5 and 6 wt% Amberlyst-15 for Methanol to oil molar ratio of 6:1, Reaction temperature of 60oC, Reaction time of 1.5 hrs, the highest ME conversion (90%) was obtained for cottonseed oil at 3wt% Amberlyst-15 catalyst loading. The transesterification was carried out at reaction temperatures of 55, 60 and 65oC for individual oils-castor, cottonseed and coconut oil and the highest ME conversions obtained for castor, cottonseed and coconut oil transesterification were 92%, 96% and 96% respectively for 60oC temperature using KOH catalyst. For homogeneous catalyst, moderate reaction temperature is enough to commence the reaction whereas for heterogeneous catalyst the operating temperature varies depending upon activation energy and conditions to produce the high yield of methyl esters. For NaOH catalyst the same optimum value of 60 oC temperature was obtained in batch transesterification process with maximum ME

The sufficient methanol vapors were generated only with reboiler temperature higher than 90oC. Depending upon the methanol concentrations, therefore, reboiler temperature in the experimental design was varied from 80oC to 120oC in order to produce smooth and consistent methanol vapor flow rates. It was found that the lower reboiler temperatures are favorable for better reactor performance. A possible reason is that with higher operating temperatures, the

It was found that cottonseed oil resulted into maximum yield of biodiesel. Usually crude cottonseed oil contains palmitic acid (22- 26%), oleic acid (15-20%), linoleic acid (49- 58%) and approximately 10% mixture of arachidic acid, behenic acid and lignoceric acid, as well as about 1% sterculic and malvalic acids. In this study, the used crude cottonseed oil contained 24.60% of palmitic acid, 17.09% of oleic acid, and 50.50% of linoleic acid. Since higher amount of free fatty acids (FFA) (>1% w/w) in the feedstock can directly react with the alkaline catalyst to form soaps, which are subject to form stable emulsions and thus prevent separation of the biodiesel from the glycerol fraction and decrease the yield, it is better to select reactant oils with low FFA content or to remove FFA from the oil to an acceptable level before the reaction. Nevertheless, the FFA (calculated as oleic acid) content of the crude cottonseed oil used in this experiment was only 0.8%, which was in an allowed level for being directly used for reaction with the alkaline catalyst to produce biodiesel.

rates of soap formation increase more rapidly than that of transesterification.

time. There was no significant rise in conversion rate after 1.5 hrs.

coconut oil at 1.5 wt% KOH catalyst loading.

conversion of 96%.

First of all, I wish to express my deepest gratitude to my supervisor Hon'ble, **Dr.V.S.Sapkal**, Vice Chancellor, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, whose guidance, encouragement, wisdom, motivation, and expectations are indispensable to my achievements and will serve as a continuous inspiration for my future career.

My deepest thanks also go to respected **Dr.R.S.Sapkal**, Head, Department of Chemical Technology, Sant Gadgebaba Amravati University, Amravati, who gave me a lot of helpful ideas, suggestions, and discussions that contribute to the remarkable success achieved in this work.

No thanks are enough to **Dr.N.B.Raut**, Assistant Professor, Faculty of Engineering, Sohar University (Affiliated to Queensland University), Sultanate of Oman, Oman for his valuable direction, motivation and constant support in accomplishment of my research.

 I would like to thank **Dr.C.V.Rode, Dr.M.G.Sane**, Senior Scientists from NCL, Pune for their technical support and guidance to my research. Thanks go to all the members in my laboratory as well as librarians of NCL, Pune, SGBAU, Amravati, SVIT, Nashik, KKW College of Engineering, Nashik for their help out in literature survey and analytical facilities in this research.

I also appreciate all my colleagues and other faculties at SVIT, Nashik, **Prof.R.N.Vaidya**, Brahma Valley College of Engineering, Nashik and **Prof.M.G.Shinde**, MET's Institute Of Engineering, BKC, Nashik for their precious direct and indirect assistance in this research work. I would thank lab assistants and staff of UDCT, Amravati for their kind cooperation during the experimentation phases. A special thanks goes to **Mr.P.R.Wankhade** for his valuable support during the experimentation phases at UDCT, Amravati.

Finally, I would like to thank my family and friends for their patience, motivation and admiration. My success is directly related to their love and strong support.
