Production of bio-fuels from renewable resources is not a
choice, but is a necessity confronting humanity today. Increasing
oil prices, declining oil reserves and the adverse effects of growing
usage of fossil energy, has encouraged researchers to look for new
sources of energy. The environmental pollutants such as unburned
hydrocarbons, nitrogen compounds, carbon monoxide and dioxide
are major disadvantages of fossil fuels. The best way out is to
return to nature and sustainable supply of energy. Use of clean,
safe, renewable and sustainable biomass energies, such as biodiesel is one of the best and safest choice to supply sustainable human
energy needs.
Biodiesel is an oxygenated diesel engine fuel consisting of
mono-alkyl esters of long chain fatty acids that has become more
attractive recently, because of its environmental benefits and the
fact that it is made from renewable lipid feedstock, such as vegetable oils or animal fats by transesterification process. The main
environmental advantages of biodiesel fuel are related to –COO
chain in its chemical structure. The presence of oxygen in biodiesel
leads to more complete combustion processes, resulting in lower
emissions of CO, particulates and visible smoke[1].
Biodiesel is produced by transesterification reaction between
lipid feedstock (triglycerides) and a short chain alcohol, such as
methanol or ethanol, in the presence of catalyst (base, acid,
enzyme or without it) with glycerin as byproduct. Because the
two reactants (alcohol and triglycerides) are immiscible with each
other, this reaction is mass transfer limited initially. High-speed
stirring is generally used to improve the contact between the
two phases. This consumes a great deal of energy, and it is not
an efficient way of contacting the two phases[2].
Ultrasound is an effective method for mixing and supplying
activation energy. Hence, using ultrasonic energy, the reaction
yield can reach more than 99 percent in a short time (less than
5 min)[3]
Production of bio-fuels from renewable resources is not achoice, but is a necessity confronting humanity today. Increasingoil prices, declining oil reserves and the adverse effects of growingusage of fossil energy, has encouraged researchers to look for newsources of energy. The environmental pollutants such as unburnedhydrocarbons, nitrogen compounds, carbon monoxide and dioxideare major disadvantages of fossil fuels. The best way out is toreturn to nature and sustainable supply of energy. Use of clean,safe, renewable and sustainable biomass energies, such as biodiesel is one of the best and safest choice to supply sustainable humanenergy needs.Biodiesel is an oxygenated diesel engine fuel consisting ofmono-alkyl esters of long chain fatty acids that has become moreattractive recently, because of its environmental benefits and thefact that it is made from renewable lipid feedstock, such as vegetable oils or animal fats by transesterification process. The mainenvironmental advantages of biodiesel fuel are related to –COOchain in its chemical structure. The presence of oxygen in biodieselleads to more complete combustion processes, resulting in loweremissions of CO, particulates and visible smoke[1].Biodiesel is produced by transesterification reaction betweenlipid feedstock (triglycerides) and a short chain alcohol, such asmethanol or ethanol, in the presence of catalyst (base, acid,enzyme or without it) with glycerin as byproduct. Because thetwo reactants (alcohol and triglycerides) are immiscible with eachother, this reaction is mass transfer limited initially. High-speedstirring is generally used to improve the contact between thetwo phases. This consumes a great deal of energy, and it is notan efficient way of contacting the two phases[2].Ultrasound is an effective method for mixing and supplyingactivation energy. Hence, using ultrasonic energy, the reactionyield can reach more than 99 percent in a short time (less than5 min)[3]
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