High Frequency Sound On Plant Matter To Create Biofuels - Iowa State University

Iowa State University researchers are employing high-frequency sound waves to break down plant substances for creation of bio-fuel. The research includes pretreating a wide range of feedstocks like witch grass, corn stover, and soft wood with constant ultrasound, thus enhancing the necessary chemical reactions needed to tansform the biomass into high-value biofuels and chemicals. All these findings shall be presented at the 21st International Congress on Acoustics (ICA 2013) being held from June2-7 in Montreal.

The researchers discovered that they could substantially up the efficiency of removing lignin (the substance that binds cellulose and hemicellulose together in plant cell walls) from biomass in solution. Generally enzymes or chemicals do the trick, but this time the researchers removed lignin by pretreating the plant matter with ultrasound. Once the lignin is removed via this technique, freed sugar gets dissolved within minutes for further processing into biofuel. The team also discovered that hydrolysis of corn starch could be greatly accelerated with ultrasonic. Traditionally, ground corn is steamed with jet cookers at high temperatures, to break down the corn and the remaining starch mash is then cooled and reacted with enzymes to release glucose for fermentation. Ultrasonically, the corn was grounded so small that it provided more surface area for enzymatic action. Economic rewards of this method are great, with less than an year payback period since installation.

A third application for ultrasound in biofuel production is the speeding up of transesterification, the major chemical reaction that transforms oil to bio-diesel. Ultrasounding soybean oil transformed it into bio-fuel within a minute, and not the regular time of 45 minutes.