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Gedayev S.R.
Head of department Microbiology, virology and immunology, Oguz han Engineering and technology University Ashgabat, Turkmenistan Ashyrova G.H.
4rd year student of Biotechnology and ecology faculty, major Microbiology,
Oguz han Engineering and technology University Ashgabat, Turkmenistan
OBTAINING BIODIESEL THROUGH TRANSESTERIFICATION METHOD IN TURKMENISTAN
Annotation
Fossil fuel are used in many areas and has an important place in the national economy. Every day decline of fossil fuel leads to economic crisis. Also, fossil fuel can be cause of increasing in the environmental impact. There is increased interest in renewable energy sources, because of finding solutions to environmental problems which fossil fuel dependent. Which is a kind of biomass energy, biofuel, can be used in diesel engines as an alternative fuel. Biodiesel is produced from renewable resources such as vegetable and animal oil. Biodiesel is sustainable, environmentally friendly, no-toxic, an alternative fuel for diesel engines.
Keywords:
Biodiesel, bioenergy, biofuel, transesterification process, biomass.
Today, the most widely used fuel in motor vehicles is gasoline. With the shortening of the life of oil reserves, there are increases in oil prices. Considering the harm that petroleum causes to nature, it is inevitable to develop an energy source that will be an alternative to petroleum. The raw materials used in alternative diesel fuels are vegetable and animal oils. Biodiesel is chemically defined as a monoalkyl ester of the fatty acid chain obtained from animal or vegetable oils. The word "bio" indicates that the fuel is of biological origin (animal and vegetable oils), and "diesel" indicates its use in diesel motor vehicles. In order to enable animal and vegetable oils to be used as fuel, emphasis has been placed on work in two areas. The first of these is the improvement of the fuel properties of vegetable and animal oils, and the second is the change in the engine type of motor vehicles . The aim of the improvement studies carried out in order to improve the fuel properties of animal and vegetable oils is to reduce the viscosities of the oils. Two methods are used to reduce viscosities: chemical and thermal. In the thermal method, it is aimed to reduce the viscosity of the oils by preheating. However, due to the problems that occur during the application of the thermal method on a moving engine, chemical methods are more widely used.
The transesterification method is defined as the process of formation of fatty acid esters and glycerin by the reaction of triglyceride molecules with alcohol and base. Biodiesel, an alternative energy source, is obtained by the transesterification reaction. In stoichiometric calculations, the molar ratio of alcohol to oil for the transesterification reaction must be at least 3:1. If methanol (CH3OH, MeOH) is used as the alcohol in the reaction, 3 moles of fatty acid methyl ester and 1 mole of glycerin are obtained at the end of the reaction. Methanol use provides more efficient results than other alcohols on the market and is obtained at low cost. In addition, alcohols such as ethanol (C2H5OH), isopropanol (C3H7OH) and butyl alcohol (C4H9OH) are also used in biodiesel production. The use of different alcohols changes the reaction conditions and makes biodiesel production more difficult. Bases are used in transesterification reactions to increase the reaction rate. The bases used are usually sodium hydroxide (NaOH) and potassium hydroxide (KOH).
Tabl
Comparison of technical characteristics of diesel and biodiesel fuel
Fuel properties Unit Limit value Biodiesel Diesel
Formula C19H35O2 C12,226H23
Molecular weight g\mol 296 120-320
Specific gravity kg\l 0,875 -0,90 0,87-0,88 0,82-0,86
Kinematic viscosity- mm2\s 2-4,5 4,3 2,5-3,5
Coefficient of friction Cetane number 49-... >55 49-55
Quantity of water mg\kg ...-200 <300 <200
The biodiesel production steps in the laboratory are as follows:
1. Mixing Base and Alcohol. The commonly used bases are NaOH or KOH, known as caustic soda. The base is dissolved in alcohol with the help of a mixer.
2.Transesterification Step. After the vegetable or animal oil is heated to 55 °C or 60 °C in a magnetic heater, the alcohol-base solution (MeOH-NaOH/KOH) is added.
The transesterification reaction is left to wait for an average of 80 hours to complete. At the end of 80 hours, a two-phase mixture of biodiesel-glycerin is obtained.
3. Separation Process. The glycerin-biodiesel mixture is separated by density difference using a separation funnel. Since the density of glycerin is higher, glycerin is collected in the lower phase and fatty acid alcohol ester (biodiesel) is collected in the upper phase. Traces of alcohol are present in both phases.
4. Alcohol Removal. After the phases are separated, the excess alcohol in each phase is removed by distillation or flash evaporation. Excess alcohol from both phases is recovered.
5. Neutralization of Glycerin. Glycerin is collected as a by-product in crude glycerin tanks as it contains bases and soap residues. Crude glycerin is obtained by removing alcohol and water residues. The obtained glycerin is used in the pharmaceutical and cosmetics industry.
6. Methyl Ester Washing. After the biodiesel-glycerin mixture is separated, the traces of soap and base in the biodiesel are removed by washing with pure water. The reaction mixture is neutralized. As a result, a light yellow colored biodiesel with a viscosity similar to petrodiesel is obtained.
The transesterification method is the process of forming biodiesel by the reaction of animal and vegetable oils with short-chain alcohols. In general, MeOH and EtOH are used.
Advantages of the transesterification method:
• It is a relatively simple and inexpensive process.
• It can be used with a wide variety of feedstocks, including waste cooking oil.
• It produces high-quality biodiesel.
Disadvantages of the transesterification method:
• The reaction is slow and requires a catalyst.
• The reaction is sensitive to water and impurities.
• The glycerin byproduct can be difficult to dispose of.
Overall, the transesterification method is a promising technology for the production of biodiesel from renewable sources. References:
1. A. Bhatnagar, S. Chinnasamy, M. Singha, KC Das, 2010. Renewable biomass production by mixotrophic algae in the presence of various carbon sources and wastewaters, Applied Energy, 88(10); 3425-3431.
2. A Richmond 2004. Handbook of microalgal culture: biotechnology and applied phycology. Blackwell Science Ltd.
© Gedayev S.R., Ashyrova G.H., 2024
