(555c) Optimization of Ultrasound-Enhanced Intensification of Biofuel Synthesis Using a Multifrequency Reactor and Taguchi Statistical Experimental Design Methodology

The recent attempts in the applications of ultrasound for the intensification of biodiesel synthesis and conversion of lignocellulosic biomass to ethanol present an urgent need to optimize the process to reduce cost of operation and make it economically attractive for large-scale applications. Cavitation is the formation, growth and implosive collapse of gas- or vapor-filled microbubbles and can be induced acoustically or hydrodynamically in a body of liquid. Acoustic or ultrasonic cavitation involves the formation and subsequent collapse of microbubbles from acoustical wave-induced compression/rarefaction. The collapse of these bubbles leads to local transient high temperatures (5000 K) and pressures (1000 atm), resulting in the generation of highly reactive species including hydroxyl (?OH), hydrogen (H?) and hydroperoxyl (HO2?) radicals, and hydrogen peroxide. The cavitation event also gives rise to acoustic microstreaming or formation of miniature eddies that enhance the mass and heat transfer in the liquid. However, little fundamental research has been carried out to date on the catalytic / biocatalytic and enzymatic conversion of lignocelluosic biofuels and biodiesel from esterification/transferication of vegetable oil via cavitation enhanced homogeneous and heterogeneous catalysis. To aid the cost-effectiveness and commercialization of cavitation-enhanced biodiesel and lignocellulosic conversion processes, the fundamental understanding of the effects of various ultrasonic parameters (e.g., frequency, intensity, etc), the transport behavior and mass transfer parameters, and the mechanistic chemistry and kinetics of the cavitation-enhanced reactions must be understood and quantified. To accomplish these objectives, we have designed and constructed several novel ultrasonic reactors to be used to quantify the kinetics and mechanisms of the important catalyzed chemical and enzymatic reactions as they relate to the production of chemicals, biodiesel and lignocelluosic biofuels. We have recently demonstrated that high-frequency ultrasound can achieve > 90% conversions of soybean oil to biodiesel within 30 min with relatively low-energy inputs via base-catalyzed transesterification using methanol and potassium hydroxide as a catalyst. We also evaluated the effects of various parameters such as ultrasonic power/ frequency, oil/methanol ratio, catalyst loading and temperature in an attempt to optimize the process. This talk will present some of the new results of our studies using a multifrequency ultrasonic reactor and Taguchi statistical experimental design methodology with both food and nonfood feedstocks.

References:

(1)N.N. Mahamuni, Y.G. Adewuyi, ?Optimization of the Synthesis of Biodiesel via Ultrasound-Enhanced Base-Catalyzed Transesterification of Soybean Oil Using a Multifrequency Ultrasonic Reactor?. Energy & Fuels, 2009, 23, 2757 - 2766.

(2) N.N. Mahamuni, Y.G. Adewuyi, "A FTIR Method to Monitor SoyBiodiesel and Soybean Oil in Transesterification Reactions, Petrodiesel Blends and Blends Adulteration with SoyOil. Energy & Fuels, accepted, 2009, 23, 3773 - 3782.

(3)Y.G. Adewuyi, B.A. Oyenekan, "Optimization of a Sonochemical Process Using a Novel Reactor and Taguchi Statistical Experimental Design Methodology". Ind. Eng. Chem. 2007, 46, 411-420.