A research on production of biodiesel from lipid of phytoplankton
Some problems which are very critical for the development of the industrial world today have happened. One is the energy crisis that must be resolved and addressed. This is due to the fact that continuous exploitation is not responsible for the fossil fuels being nonrenewable energy. This will have an impact on the scarcity of fossil fuels, thereby increasing the price of fuel oil (BBM) world. Diversification of energy is one solution to solve the problem, but the problem of saving the environment should also be considered, because almost every sector of public life cannot be separated from the use of fuel, which in fact resulted in environmental pollution, especially air pollution caused by vehicle emissions [
This situation has made most of the countries in the world (one of them is Indonesia) seek sources of alternative fuel that can be developed from other basic materials that are renewable and environment friendly [
Indonesia is an archipelago with two-thirds of the area being the sea and the longest coastline in the world, which is 80791.42 km, is rich in aquatic biological resources, and which are very abundant both in kind and quantity. One of Indonesia’s natural potentials is microalgae or phytoplankton [
Research on microalgae as a raw material of biodiesel, especially marine phytoplankton, has been carried out. However, research on the culture of phytoplankton that produced fats for biodiesel used as base material is still less common, particularly marine phytoplankton
Marine phytoplankton
For biodiesel production, lipids and fatty acids of natural sources have to be extracted from dry biomass of them like microalga biomass. Extraction methods such as ultrasound and microwave assisted were also used for oil extraction from natural sources. Biodiesel is a mixture of fatty acid alkyl esters obtained by transesterification (ester exchange reaction) of vegetable oils or animal fats. Transesterification is a multiple-step reaction, including three reversible steps in a series, where triglycerides are converted to diglycerides; then diglycerides are converted to monoglycerides, and monoglycerides are then converted to esters (biodiesel) and glycerol (by-product) [
The main problem in the biodiesel production process is that alcohol and oil as the main raw materials are not intermingled (immiscible). Stirring is a technique commonly used so that alcohol and oils can be mixed with each other so that the reaction can be run up to the formation of biodiesel, but mixing requires a relatively large energy [
From several studies that have been conducted, the use of ultrasonic waves has proven to accelerate the reaction, reducing the amount of catalyst used and reducing the ratio of oil to alcohol use than the reaction without the help of ultrasonic waves. This is due to the fact that ultrasonic wave energy arises from acoustic cavitation process (acoustic cavitation) which consists of the formation, growth, and collapse (implosive collapse) of the bubble formed. Ultrasonic waves cause the mechanical effects on the reaction to enlarge the surface area through microgap formation on the surface, accelerating dissolution, or increase the rate of mass transfer [
The materials used in this research work include phytoplankton cultures derived from
The apparatus used in this research work included glass tools which are generally used in the laboratory, jars made
Seawater is collected in a container and then sterilized subsequently measured by using a salinometer salinity and filtered using filter paper. Conway media added into sterile seawater and conditioned with aeration process CO2 gas then phytoplankton added into of those. After that, density of phytoplankton are calculated.
Determination of phytoplankton growth pattern is done counting the number of cells per milliliter of medium every 24 hours. Samples are taken with a sterile pipette, dropped about 0.1–0.5 mL on haemocytometer, and then observed through a microscope [
Marine phytoplankton
Pure lipids from marine phytoplankton
Analyses of the physical properties are density and viscosity. Density analysis procedures were carried out by the method ASTM D1475 and viscosity analyses were carried out by the method ASTM D445.
Analyses of the chemical properties are content of free fatty acid (% FFA), saponification value, and iodine value. Procedures of free fatty acids (% FFA) were based on the AOCS method Ca 5a-40, saponification value was based on AOCS method Cd 3-25, and value iodine was based on Wijs method.
Observations of marine phytoplankton growth pattern
Chart patterns of marine phytoplankton growth
Based on Figure
Early stages of biodiesel production from phytoplankton were isolation lipid of phytoplankton
Extracted in the form of lipids dissolved in 96% ethanol and then separated by means of solvent is evaporated until all ethanol 96% were used separately in order to obtain the pure lipid. Lipid weight of
Synthesis biodiesel from phytoplankton lipid was done by transesterification using methanol (1 : 12). It was accelerated by the addition of KOH alkaline catalyst (9% of lipid weight). Time of transesterification reaction was around 180 minutes with a heating temperature of 50–60°C using an ultrasonic cleaner tool which is operated at a frequency of 40 kHz. Then, the reaction was left for 3-4 days to form two layers. The top layer was a layer of green biodiesel murky yellow, while the bottom layer is a layer of glycerol golden brown, which can be seen in Figure
(a) Lipid of phytoplankton
Having obtained the two layers, the upper and lower layers were separated. The top layer was then centrifuged to remove impurities and glycerol which may end up at the time of separation. The remaining methanol in the biodiesel that does not react is removed by heating in an oven at a temperature of 70°C. Subsequently obtained pure biodiesel can be seen in Figure
Biodiesel of phytoplankton
Weight of biodiesel is produced 9.15 grams with yield 35.35%. This is due to the fact that the fatty acids in the lipid component of phytoplankton have not reacted completely with methoxy ions in the transesterification reaction. Factors that could cause this are that the temperature and reaction time are not optimal. Biodiesel produced from phytoplankton also has a characteristic yellow color.
The next stage of the synthesis results of biodiesel from lipids phytoplankton
Result of density and viscosity analysis.
Density (g·cm−3) | Viscosity (cSt) | ||
---|---|---|---|
Result of research | Standard ASTM D6751 | Result of research | Standard ASTM D6751 |
0.88 | 0.82–0.90 | 1.14 | 1.60–5.80 |
Biodiesel produced from lipid phytoplankton
When compared to the standard ASTM D6751, the biodiesel from the phytoplankton species can be said to be included in the range of density values that have been set.
Viscosity is one of the standards in determining the quality of biodiesel and has a very important role in the process of fuel reinjection. Low viscosity value can lead to leakage of fuel injection pump and if too high can affect the work quickly and make carburetion injector fuel [
One of the causes of high and low viscosity grades is using the catalyst concentration and temperature. If concentration of catalyst is high, so the viscosity will decrease. This is because the concentration of excess catalyst will accelerate the breakdown of fatty esters triglyceride into three grades which will reduce the viscosity of 5–10%.
Kinematic viscosity results obtained in this research work were 1,14 cSt where the value which is smaller than the standard value of kinematic viscosity range recommended in ASTM D6751 is equal to 1.60 to 5.80 cSt. This is due to the persistence of residual methanol in the biodiesel that was contained in the viscosity value obtained which is rather small.
Characterization of the chemical properties test was based on ASTM D6751 biodiesel made after the physical properties test is completed. Chemical properties of biodiesel test include the analysis of free fatty acid content (% FFA), saponification value, and iodine value. Results of analysis of free fatty acid (% FFA), saponification value, and iodine value can be seen in Table
Results of analysis of free fatty acid (% FFA), saponification value, and iodine value.
Analysis | Result of research | Standard ASTM D6751 |
---|---|---|
Free fatty acid content (% FFA) | 0.43 | <0.45 |
Saponification value (mg KOH/g) | 5.42 | <500 |
Iodine value (g I2/100 g) | 20.90 | <115 |
Free fatty acid value of biodiesel results of this research in which the value of 0.43% met the standard levels of free fatty acids/FFA (%) biodiesel recommended in ASTM D6751 is 0.45%.
Levels of free fatty acids that can cause deposition in combustion systems are also an indicator that the fuel can serve as a solvent which can lead to a reduction in the quality of the fuel system.
The higher the free fatty acids, the lower the quality of diesel fuel. High free fatty acids may also reduce the life of the pump and filter.
Saponification number is defined as the milligrams of KOH required to neutralize one gram sample lipid or oil. The lower the molecular weight, the higher the saponification number and vice versa [
Saponification value results obtained of this research is 5.42 mg KOH/g where the value which is smaller than the standard value of saponification value in ASTM D6751 is less than 500 mg KOH/g. Based on these data biodiesel from
Iodine numbers in biodiesel showed unsaturation level of the building blocks of biodiesel. On the one hand, the presence of unsaturated fatty compounds improved the performance of biodiesel at low temperatures because this compound has a melting point (melting point) that correlated with a lower cloud point and pour point was also low [
Biodiesel with high iodine numbers will produce esters with the flow and solidification at low temperature. Biodiesel which has a higher degree of unsaturation is not suitable for use as biodiesel because unsaturated molecules will react with oxygen from the atmosphere, be converted into peroxide crosslinking, result in the unsaturated, and cause biodiesel polymerized to form a similar plastic material, especially if the temperature increases. As a result, the diesel engine will not work properly and be damaged [
Biodiesel produced from lipid phytoplankton
Lipid phytoplankton
The authors declare that there is no conflict of interests regarding the publication of this paper.