Development and optimization of technology for the extraction and conversion of micro algal lipids

232 Pages·2015·4.13 MB·English

Development and optimization of technology for the extraction and
conversion of micro algal lipids to biodiesel

K Ramluckan

Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in
Chemistry in the Faculty of Applied Sciences at the Durban University of
Technology.

2015

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ABSTRACT

Fossil fuel reserves have been diminishing worldwide thus making them very scarce
in the long term. These fuel sources and their by-products which are used
commercially tend to produce large quantities of emissions. Some of them are
believed to be toxic to flora and fauna. It is primarily for this reason that researchers
worldwide have begun to seek out alternative sources of environmentally safe fuel.
Biodiesel from algae is one of these sources that have been examined over the last
few decades. Biodiesel has been produced from other plant-based material and waste
oils in countries like America and Japan. However, the use of food based crops for
biodiesel production has been challenged as it has an impact on food production on
an international scale. Algae have only recently been investigated for their feasibility
for biodiesel production on a large scale.

The aim of this study was to investigate and develop technologies for biodiesel
production from algae. The species of algae chosen were chlorella sp and
scenedesmus sp., since they are indigeneous to Kwazulu Natal in South Africa.
Samples were obtained from a local raceway pond and prepared for analysis. Drying
protocols used freeze, oven and sun drying for initial preparation of the samples for
analysis. Sun drying was the least energy intensive but most time consuming. At
laboratory scale, oven drying was chosen as the best alternative. Lipid extraction
methods investigated were the separating funnel method, the soxhlet method,
microwave assisted extraction (MAE) and the expeller press. Thirteen solvents
covering a range of polarities were used with the extraction methods to determine the
efficiency of the solvent with these methods. Optimization of the MAE method was
conducted using both the one factor at a time (OFAT) method and a design of
experiment (DOE) statistical method. The shelf life of algal biomass was determined
by ageing the samples for approximately three months. Direct and in-situ
transesterification of lipid extracts to produce biodiesel was investigated using both
acid and base catalysis. Qualitative and quantitative analyses were conducted using
Fourier transform infra-red (FTIR) and gas chromatography (GC). Chemical and
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physical characterization of the biodiesel produced from the algal lipid extracts were
compared to both local and international standard specifications for biodiesel.

In terms of extraction efficiency, it was found that soxhlet and microwave assisted
extraction methods were almost equally good. This was proved by the MAE method
yielding an average of 10.0% lipids for chloroform, ethanol and hexane after 30 mL
of solvent was used in an extraction time of 10 minutes, while the soxhlet method
yielded 10.36% lipids using an extraction volume of 100 mL of solvent with an
extraction time of 3 hours. Chloroform, ethanol and hexane were more efficient than
the other ten solvents used. This was shown by these three solvents producing lipid
quantities between 10% to 11% while all the other solvents produced lipid quantities
between 2 and 10 %. The best extraction efficiency was achieved by the binary
solvent mixture made up of chloroform and ethanol in a 1:1 ratio. Under the
conditions optimized, this solvent ratio yielded a lipid content of 11.76%.

The methods chosen and optimized for extraction are very efficient, but the actual
cost of production of biodiesel need to be determined. Physical methods like the
expeller press are not feasible for extraction of the type of biomass produced unless
algae are pelletized to improve extraction. This will impact on the cost of producing
biodiesel. The transesterification protocols investigated show that the base catalysis
produced biodiesel with a ratio of saturates to unsaturates conducive to a good fuel
product. The direct esterification method in this study proved to be better than the in-
situ method for biodiesel production. The in-situ method was also more labour
intensive. Chromatography was found to be a fast and efficient method for
qualitative and quantitative determination of biodiesel. Characterization tests showed
that the quality of biodiesel produced was satisfactory. It also showed that the
methods used in this study were feasible for the satisfactory production of biodiesel
which meets local and international specifications.

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DEDICATION

Dedicated to my beloved parents Ramluckan and Deomathie Unnur who would have
been proud of this achievement.
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ACKNOWLEDGEMENTS

My heartfelt thanks to my patient and loving wife, Sanitha, my son, Kishal, daughter,
Shetal and son-in-law, Vernon, without whose constant support and encouragement
this would not have been possible.

My sincere thanks to my supervisors, Prof F Bux and Prof K G Moodley for their
motivation and support. I cannot thank you enough for the time you have dedicated
to assist me.

Thank you to my special friends, Miss Arthi Ramrung, Mr Naresh Ramnarayan and
Dr Feroz Swalaha for always being there when I needed their assistance or input.
Thank you to Mr Narain Maharaj for his assistance with lectures and to all my
colleagues and friends in the Chemistry department.

Thank you to all my friends and colleagues at the Institute of water and waste water.
(IWWT) who assisted with sampling. Here a special thank you must go to Mr Bishan
Soni, Mr Abhishek Guldhe, Dr Bhaskar Singh, Mr Luveshan Ramannah, Mr Ismail
Rawat, Dr Nishani Ramdhani and Miss Virthie Bhola for their assistance during the
course of my study.

My sincere gratitude to my students, Miss Sarika Ramluckan and Miss Thaira Gany
for assistance rendered at the beginning of this project.

Thank you to my brother, sisters and other very special members of my family for
their support and encouragement.

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PREFACE
Aspects of the work covered in the following thesis can be found in the following
accepted publication and conference presentation:
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The following publication has been prepared and has been submitted for review:

Title
The evaluation and optimization of parameters for the Microwave assisted extraction
(MAE) method for the extraction of lipids from algal biomass.
Krishan Ramluckana, Kandasamy G Moodleyb, Feroz M Swalahac, Faizal Buxd,
abDepartment of Chemistry, Durban University of Technology.
cDepartment of Biotechnology, Durban University of Technology.
dInstitute for Water and Waste Water Technology, Durban University of Technology,
P O Box 1334, Durban, 4000.

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TABLE OF CONTENTS
TITLE………………………………………………………………………………... i
DECLARATION BY STUDENT……………………………………………………ii
ABSTRACT………………………………………………………………………....iii
DEDICATION………………………………………………………………………..v
ACKNOWLEDGEMENTS……………………………………………………….…vi
PREFACE…………………………………………………………………………….v
TABLE OF CONTENTS……………………………………………………………..x
LIST OF FIGURES………………………………………………………………...xvi
LIST OF TABLES…………………………………………………………………. xx
LIST OF ABBREVIATIONS…………………………………………………….xxiii

CHAPTER 1: INTRODUCTION…………………………………………..1

CHAPTER 2: LITERATURE REVIEW
2.1 Algae selection, cultivation and harvesting ………………………………...10
2.2 Sampling and sample preparation…………………………………………...13
2.2.1 Sampling methods…………………………………………………...13
2.2.2 Sample Preparation.............................................................................14
2.2.3 Drying of algae……………………………………………………...14
2.2.4 Storage of algae…………………………………………………......16
2.2.5 Qualitative analysis of lipids using Nile red………………………...17
2.3 Methods for extraction and optimization……………………………………18
2.3.1 Separating funnel extraction………………………………………...18
2.3.2 Soxhlet extraction…………………………………………………...19
2.3.3 Microwave-assisted solvent extraction (MAE)……………………..22
2.3.4 Expeller……………………………………………………………...26
2.3.5 Other methods……………………………………………………….26
2.3.5.1 Supercritical fluid extraction (SFE)…………………………26
2.3.5.2 Ultrasound/sonication………………………………………27

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