The Application of Ultrasound in the Enzymatic Hydrolysis of Switchgrass

Abstract

In a series of experiments, untreated and ammonium hydroxide pretreated Klenow lowland variety switchgrasses are converted to reducing sugars using low-frequency (20 kHz) ultrasound and commercially available cellulase enzyme. Results from experiments using untreated and pretreated switchgrasses with and without ultrasound are presented and discussed. In untreated switchgrass experiments, the combination of ultrasound and enzymes resulted in an increase of 7.5% in reducing sugars compared to experiments using just enzymes. In experiments using ammonium hydroxide pretreated switchgrass, the combination of ultrasound and enzymes resulted in an increase of 9.3% in reducing sugars compared to experiments using just enzymes. Experimental evidence indicates that there is a synergistic effect from the combination of ultrasound and enzymes which lowers the diffusion-limiting barrier to enzyme/substrate binding and results in an increase in reaction rate. Scanning electron microscopic images provide evidence that ultrasound-induced pitting increases substrate surface area and affects reaction rate and yield.

Intensification of enzymatic hydrolysis of waste newspaper using ultrasound for fermentable sugar production

“…The ultrasound applied in the enzyme catalysis process accelerates the contact of the enzyme and the substrate in the reaction process. The combined effect of cavitation phenomenon, mechanical and thermal energy produced by the ultrasonic waves causes a certain degree of impact on the substrate and the enzyme molecules, which increases their contact surface area, resulting in an increased reaction rate and a faster rate of release of products [21]. Therefore, the catalysis effect of cellulase enzyme was improved, that is, the saccharification rate was increased.…”

Mechanochemical production of lignin-containing powder fuels from biotechnical industry waste: A review

“…Several processing methods of plant raw materials have been developed to obtain soluble carbohydrates [1,2]: -dissolution of lignin by chemical reagents such as caustic alkalis, ammonia, chlorites, sulfur dioxide, amides, dilute and concentrated acids, which is widely used in the production of pulp and paper [3], -explosive autohydrolysis [2,4], -enzyme treatment or treatment by enzyme-producing fungus strains [5], -microwave radiation [6], -ultrasound treatment [7], -electron beam treatment [8], and -g-radiation [9].…”

Ultrasound irradiation in the production of ethanol from biomass

“…Easson et al [59] reported that ultrasound-induced pitting increases substrate surface area of switchgrass and affects the reaction rate and yield. The structure of sweet sorghum exposed to the ultrasound irradiation was also opened up to resemble more sponge-like structures, which could also provide higher surface areas [46].…”

“…In another study, it was found that the ultrasonic treatment of switchgrass resulted in an increase of 7.5% in releasing fermentable sugars, but 9.3% in experiments using ultrasound on switchgrass soaked in ammonium hydroxide [59]. However, the net energy balance was not favorable and further investigations on re-evaluating the design and conditions were recommended in order to improve ultrasonic treatment of lignocellulosic materials.…”