Sugarcane bagasse (SCB) was treated in three stages using ozone oxidation (O), washing in an alkaline medium (B) and ultrasonic irradiation (U). The impact of each pretreatment stage on the physical structure of the SCB was evaluated by its chemical composition, using an infrared technique (FTIR-ATR), and using thermogravimetric analysis (TGA/DTG). The pretreatment sequence O, B, U provided a significant reduction of lignin and hemicellulose, which was confirmed by changes in the absorption bands corresponding to these compounds, when observed using infrared. Thermogravimetric analysis confirmed an increased thermal stability in the treated sample due to the removal of hemicellulose and extractives during the pretreatment. This pretreatment released 391mg glucose/g from treated SCB after the enzymatic hydrolysis, corresponding to a yield of 94% of the cellulose available.

Modifications in sugarcane bagasse (SCB) from ozonolysis (O) NaOH (B) and ultrasound (U) (OBU) treatment for cellulosic ethanol production by enzymatic hydrolysis, were evaluated when increasing the exposure time of SCB to ozone. The lignin, cellulose, and hemicellulose after treatment were quantified: lignin removal and a consequent increase in cellulose content were shown using an infrared spectroscopic technique (ATR-FTIR) and chemical characterization. X-ray diffraction analysis (XRD) proved that OBU treatment does not affect the crystalline cellulose portion and electron microscopy techniques established that the fiber region most affected by the OBU treatment was the secondary cell wall, where the greatest lignin content is located. For OBU-60 treatment the lignin content was reduced and consequently there was a significant increase in cellulose content. After enzymatic hydrolysis, this pretreated SCB released 418mgglucose/g, corresponding to six times more than untreated SCB and a yield of 93% of the cellulose available.

Hydrophobic carriers can be used to improve the activity, stability and other properties of enzymes. Physical agents, like ultrasound, may also contribute to improving the dispersion and collision of the reagent molecules, decreasing the reaction time and intensifying the catalytic process. However, its effect on the enzyme activity and reaction selectivity is still not entirely understood. Here, enzyme modulation of immobilized lipases was studied under pulsed ultrasound irradiation in fatty acid ethyl ester (FAEE) synthesis for biodiesel production. Novozym 435® and two commercial lipases from Thermomyces lanuginosus and Rhizomucor miehei, immobilized on Octadecyl-Sepabeads were used as a biocatalyst in the transesterification reaction of vegetable oils and ethanol. The use of ultrasound associated with catalysis by the Novozym 435 increased the production of FAEE by about three times (from 8.9 to 26.4%) using soybean oil and changes were observed in the profile of the products. From the sonicated reaction, ethyl-palmitate production decreased from 23.4 to 11.7%, while the ethyl-linoleate content rose from 47.5 to 59.2%. On the other hand, the T. lanuginosus lipase was less affected by sonication with the overall production of FAEE increasing from 17.2 to 24.1%, with ethyl-palmitate and ethyl-linoleate content changing from 16.2 to 17.5% and 55.0 to 47.8%, respectively. Although the changes in the production yield are not too high, the main idea here was to show that ultrasound modulates the lipase activity as well as its respective selectivity. Thus, ultrasound, is responsible for changing the ethyl ester production, which can be applied to many other biochemical processes to improve or modulate their synthesis yield.