Biodiesel Fuel Production from Marine Microalgae Isochrysis galbana, Pavlova lutheri, Dunaliella salina and Measurement of its Viscosity and Density  

T. Sujin Jeba Kumar , C.K. Balavigneswaran , K.P. Srinivasakumar
Inbiotics, Parvathipuram, Nagercoil-629003, Kanyakumari District, Tamil Nadu, India
Author    Correspondence author
International Journal of Marine Science, 2013, Vol. 3, No. 5   doi: 10.5376/ijms.2013.03.0005
Received: 24 Dec., 2012    Accepted: 21 Jan., 2013    Published: 24 Jan., 2013
© 2013 BioPublisher Publishing Platform
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Kumar et al., 2013, Biodiesel Fuel Production from Marine Microalgae Isochrysis galbana, Pavlova lutheri, Dunaliella salina and Measurement of its Viscosity and Density, International Journal of Marine Science, Vol.3, No.5 33-35 (doi: 10.5376/ijms.2013.03.0005)


Biodiesel is a fuel derives from transesterification of fats and oils. It is renewable and non-toxic ecofriendly fuel with less CO2 and NO2 emissions. Microalgae are known to contain more lipid content than macroalgae and most other oil crops. In this study, we extracted biodiesel from three microalgae Isochrysis galbana, Pavlova lutheri, Dunaliella salina and also measured the density and viscosity of biofuel obtained from these microalgae. Pavlova lutheri yielded more oil than the other two algae with biomass left over Dunaliella salina was more. The density of biodiesel obtained from these microalgae was between 0.86 g/cmand 0.90 g/cm3 with viscosity in the range 3.92 mm2/sec to 4.5 mm2/sec showing high density than the other oils.

Marine microalgae; Biofuel; Transesterification; Viscosity; Density

The demand for energy is increasing continuously, because of increases in industrialization and population. The basic sources of this energy are derived petroleum, natural gas, coal, hydro and nuclear powers (Kulkurni, 2006). Biomass is one of the better sources of energy (Kulkurni, 2006). Large-scale utilization of biomass energy could contribute to sustainable development on several fronts, environmentally, socially and economic (Turkenburg, 2000). Biodiesel is one of such alternative fuel, which is obtained by the transesterification of triglyceride oil with monohydric alcohols. It has been well-reported that biodiesel obtained from canola and soybean, palm, sunflower oil, algal oil as a diesel fuel alternative (Lang et al., 2002; Spolaore et al., 2006). 
Biodiesel is a nontoxic and biodegradable alternative fuel that is obtained from renewable sources. The burning of an enormous amount of fossil fuel has increased the CO2 level and other greenhouse gases in the atmosphere, causing global warning. Biomass has been focused on as an alternative energy source. Since it is a renewable resources and it fixes CO2 in the atmosphere through photosynthesis. Algae produce 7 to 31 time greater oil than palm oil. It is very simple to extract oil from algae. Microalgae have an efficient photosynthetic system. Microalgae have much more oil than macro algae and it is faster and easier to grow (Shay, 1993). The most significant difference in algal oil is in the yield and hence its biodiesel yield. According to some estimates, the yield (per acre) of oil from algae is over 200× compared with the best-performing plant/vegetable oil (Sheehan et al., 1998). Several researches confirm the good biodegradability of biodiesel fuels in aqueous medium and soil. This is observed in mixtures of biodiesel and diesel fuel too (Pasqualino et al., 2006). Biodiesel of vegetable origin seems to improve the biodegradability more than that from used eatable oils (Pereira and Mudge, 2004). Biodiesel is produced through a reaction known as transestrification (Romos et al., 2009). Generally transesterification can be catalyzed by base or acid. However, in homogeneous catalysis, alkali catalysis is a much more rapid process than acid catalysis (Freedom et al., 1984).
Kinematic viscosity and density are the parameters required by biodiesel and diesel fuel standards because of being key fuel properties for diesel engines. In a diesel engine, the liquid fuel is sprayed into compressed air, and atomized into small drops near to the nozzle exit. Viscosity affects the atomization quality, size of fuel drop and penetration (Hewood, 1988; Lichty, 1967). Density is a key fuel property, which directly influences the engine performance characteristics. Many performance characteristics, such as cetane number and heating value, are analogus to the density (Tat et al., 2000).
1 Results and Discussions
The importance of microalgae oil production are high lipid yield and high biomass productivity which can affect production costs (Rodolfi et al., 2009). So, from Table 1 the three micro algae used for production of biodiesel maximum amount of oil were obtained from Pavlova lutheri which shows its high lipid content. There was no significant difference in pH between the biodiesel produced from these three micro algae. Our results prove that biodiesel from micro algae contains much more lipid content than macro algae as in different reports. In many studies, it was observed that biodiesel’s density has not changed a lot, because the densities of methanol and oil are close to the density of the produced biodiesel (Graboski et al., 1998). So in our results, the density of biodiesel varies between 0.86 g/cm3 and 0.90 g/cm3. This is depicted in Table 2. The viscosity values were in the range from 3.92 mm2/sec to 4.5 mm2/sec. It is higher than those of the diesel fuels. The algae are therefore, an economical choice for biodiesel production because of its availability and lost cost and capable of meeting the global demand for transport fuels. Like plants micro algae use sunlight to produced oils but they do so more efficiently than crop plants. Therefore, oil productivity of these micro algae greatly exceeds the oil productivity of the finest producing oil crops. Further research is going on these micro algae for biodiesel production, its chemical analysis and statistical significance. 


Table 1 Measurement of fresh and dry weight, extracted and biomass of algae


Table 2 Density and viscosity analysis of biodiesel


2 Materials and Methods
2.1 Algae culture
The algae namely Isochrysis galbana, Pavlova lutheri, Dunaliella salina were procured from CMFRI, Tuticorin. The algae were cultured in modified Walney’s medium. The algae were grown under low illumination up to 50 µmol•m-1•s-1 d and unlimited aerated condition for one week. Temperature was adjusted to (25±2)℃.


2.2 Biodiesel extraction
2.2.1 Oil extraction 
Algae were grounded with motor and pestle as much as possible. The ground algae were dried for 20 min at 80℃ in a incubator to remove water. Hexane and ether solution (1:1) were mixed thoroughly with the dried ground algae to extract oil. Then the mixture was kept for 24 h for settling.

2.2.2 Biomass extraction
The biomass was collected after filtration and weighed.

2.2.3 Evaporation
The extracted oil was evaporated in vacuum to release hexane and ether solutions using rotary evaporator.

2.2.4 Mixing of catalyst with methanol
0.25 g NaOH was mixed with 25 mL methanol and stirred properly for 20 min.

2.2.5 Biodiesel production
The mixture of catalyst and methanol was poured into the algal oil in a conical flask. The following reaction and steps were followed.

2.2.6 Transesterfication
The reaction process is called transesterification (Figure 1). The conical flask containing solution was shaken for 3 h by electric shaker at 300 rpm.


 Figure 1 The reaction process of transesterification


2.2.7 Shetteling
After shaking the solution was kept for 16 h to settle the biodiesel and sediment layers clearly.

2.2.8 Separation of biodiesel
The biodiesel was separated from sedimentation by flask separator carefully. Quantity sediment (glycerin, pigments, etc.) was measured.

2.2.9 Washing
Biodiesel was washed thoroughly by 6% water until it was become clean.

2.2.10 Drying and storage
Biodiesel were kept in a dryer and production was measured by using measuring cylinder. pH values were evaluated and stored for analysis.

2.3 Density Measurement
Density is defined as a mass of an object divided by its volume. ASTM standard D941 test method was used to measure the density of the biodiesel fuel. The measurements were done at 15℃ by using Anton Paar (DMA 35N). The measurement was conducted five times for each sample and the final results were the mean value. The measured densities and calculated value for each algal biofuel were tabulated in Table 1.

2.4 Viscosity Measurement
Viscosity is defined as the resistance to follow of a fluid. In order to measure the viscosities of the algal biofuels ASTM Standard D445 test method was used. The kinematic viscosity was determined at 40℃ by multiplying the constant of viscometer tube and the measured efflux time, which is the time for a known volume of liquid flowing under gravity to pass through a calibrated glass capillary viscometer tube. The measurements for viscosities were done five times for each sample and the results were the mean value. 
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