Faculty of Applied Sciences
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Item An evaluation of the efficacy of using selected solvents for the extraction of lipids from algal biomass by the soxhlet extraction method(Elsevier, 2013-08-14) Ramluckan, Krishan; Bux, Faizal; Moodley, Kandasamy G.The use of solvents for the extraction of lipids from algal biomass has been a method of choice for many years. The soxhlet extraction method was chosen because of its simplicity in operation, relative safety and potential for upscaling to industrial plant level. The source of algal biomass was a raceway pond. Chlorella sp. which is known to produce larger amounts of oil than other indigenous species was used for this investigation. Thirteen solvents spanning a range of polarities and solubilities were selected for this study. Extraction methodology involved the use of single solvents, selected binary solvent mixtures and time-based extractions which were varied from 1 to 5 h. Ultraviolet (UV) spectroscopy was used to determine chlorophyll content of the lipid extracts and gas chromatography was used for the identifica-tion and quantitation of the lipids. Analysis showed that ethanol, chloroform and hexane were generally more efficient in the extraction of lipids than the other solvents studied, producing lipid contents in excess of 10%. The time-based trials indicated that the optimum extraction time was 3 h for the solvents selected. The binary solvent mixture with the greatest extraction efficiency (i.e. >10% lipid extract) was obtained with the 1:1 mixture of chloroform:ethanol. Chlorophyll quantities varied for each solvent extract with chloroform and methanol producing the highest values at >1%. Chromatography was effec-tive in identifying lipids used in the production of biodiesel.Item Development and optimization of technology for the extraction and conversion of micro algal lipids to biodiesel(2015) Ramluckan, Krishan; Moodley, Kandasamy Govindsamy; Bux, FaizalFossil 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 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.Item The evaluation of liquid hydrocarbon contamination of soil around petrochemical tank farms at a Durban refinery(2004) Ramluckan, KrishanThe primary objective of this study was to determine the levels of liquid hydrocarbon contamination present in the soil within the SAPREF refinery. The secondary objective arising from this was the development of a gas chromatographic (GC) method using a fifty metre PONA (Paraffin, Olefin, Naphthalene and Aromatic) capillary column and the split injection technique, for the analysis. Toluene was the solvent selected, with the Standard method for the BÜCHI extraction system, to extract the hydrocarbons present in the soil samples taken at the five different tank farm sites in the refinery. The main purpose of the analysis and evaluation was to enable the refinery to establish environmental control measures to reduce the contamination of the soil in the area.