Acceleration of the Enzymatic Hydrolysis of Cotton Waste Celluloses by Low Intensity Uniform Ultrasound Field

The cost-competitive production of bio-ethanol and other biofuels is currently impeded, mostly by high cost and low efficiency of enzymatic hydrolysis of feedstock biomass and especially plant celluloses. Despite substantial reduction in the cost of production of cellulolytic enzymes in recent times, the actual conversion of plant cellulose into sugars still remains an expensive and slow step. Our research has found that the introduction of a low energy, uniform ultrasound field into enzyme processing solutions greatly improved their effectiveness by significantly increasing their reaction rate. It has been established that the following specific features of combined enzyme/ultrasound bio-conversion of cotton waste celluloses are critically important: a) cavitation effects caused by introduction of ultrasound field into the enzyme processing solution greatly enhance the transport of enzyme macromolecules toward the substrate’s surface, and b) mechanical impacts, produced by the collapse of cavitation bubbles, provide an important benefit of “opening up” the surface of solid substrates to the action of enzymes. On a laboratory scale, introduction of low level, uniform ultrasonic energy in the reaction chamber during enzymatic hydrolysis of cotton lint and cotton gin waste celluloses resulted in a significant improvement in enzyme efficiency. The combined enzyme/sonication hydrolysis of cotton lint and cotton gin trash and similar plant celluloses could significantly accelerate this critical step in the overall conversion of agricultural waste biomass into biofuels.