Effect of Water Activity on Transesterification Kinetic Parameters of Coconut Oil with Ethanol.
ABSTRACT
This work is focused on determining quantitatively how water, even in its smallest amount, affects transesterification kinetic parameters of coconut oil with ethanol;
with the view of assessing whether it is preferable to use anhydrous ethanol with high price or ethanol containing a certain amount of water in biodiesel production process. Physicochemical properties of the coconut oil were also determined.
The coconut oil produced was yellow and had the following values for viscosity, 21.24 ± 0.22mm 2 /s, relative density, 0.92 ± 0.001, flash point, 1900 C, cloud point, +27, pour point, +25, refractive index, 1.45 ± 0.001 and moisture content, 0.1%.
The average acid, iodine, peroxide and saponification values of the coconut oil were 0.523 ± 0.03 mgKOHg-1, 9.33 ± 0.04 mgIodineg-1, 0.00 meq/1000g and 270.26 ± 0.05 mgKOHg-1 respectively.
The crude coconut oil was transesterified using serially diluted anhydrous ethanol with water activity 0.002, 0.022, 0.042, 0.062 and 0.102. NaOH was used at constant reaction conditions.
The ethyl ester produced (biodisel) was light yellow with the following values for viscosity 2.66 ± 0.22mm 2 /s, relative density, 0.86 ± 0.001, flash point, 1420 C, cloud point, +5, pour point, -3, refractive index 1.43 ± 0.001 and moisture content 1.7%.
INTRODUCTION
As energy demands extremely increase while the energy sources are limited, a number of current studies focus on development of alternative fuels (Jha et al, 2007). One of such alternative fuels for combustion in compression-ignition (diesel) engines is the biodiesel.
Biodiesel is defined as a fuel composed of mono-alkyl esters of long-chain fatty acids derived from renewable lipid feedstock such as vegetable oils or animal fats, for use in compression ignition (diesel) engines (National Biodiesel Board, 1996).
Furthermore, biodiesel is oxygenated, sulfur-less, non-toxic and biodegradable biofuel suggestively because their lipid sources possess these qualities. It is natural and renewable; producing less pollution than petro diesel (Wassell and Dittmer, 2006).
Biodiesel came to be established as an alternative fuel after it was discovered that vegetable oils originally used in the diesel engine were problematic (with poor fuel atomization, incomplete combustion, carbon deposition on the injector and piston etc) (Ramadhas et al., 2005).
These engine problems that were due primarily to high viscosities and low volatilities of the vegetable oil were however, resolved through several chemical processes such as micro-emulsion, preheating the oil, pyrolysis, blending, transesterification and the use of viscosity reducers (Srivastava and Prassad, 2000;
Peterson et al., 1991; Ma and Hanna, 1999; Muniyappa et al., 1996). Among these, transesterification was considered as the most suitable modification because technical properties of esters are nearly similar to diesel.
Transesterification is a chemical reaction involving oil or fat, and a short chain alcohol such as methanol or ethanol to yield fatty acid alkyl esters and glycerol ((Pinto et al., 2005; Thiruvengadaravi et al., 2009).
Through transesterification, these vegetable oils are converted to the alkyl esters of the fatty acids present in the vegetable oil. These esters are commonly referred to as biodiesel.
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StudentsandScholarship Team.
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