Ultrasound-assisted acid hydrolysis of palm leaves (Roystonea oleracea) for production of fermentable sugars

This work is focused on the ultrasound-assisted hydrolysis of palm leaves to obtain fermentable sugars using phosphoric acid as catalyst. The effects of phosphoric acid concentration (5.0–20 wt%) and temperature (30–65 °C) on the hydrolysis and kinetic parameters were evaluated. The maximum amounts of fermentable sugar obtained were 0.55 and 0.59 g sugar g−1 dry material, leading to maximum efficiencies of hydrolysis of 68.8 and 74.0% in the absence and presence of ultrasound, respectively. The kinetic parameters obtained from the overall reaction curves showed that the ultrasound intensified the releasing of fermentable sugars in the period of constant reaction rate, since 51% of total fermentable sugar was released in this period in comparison with 45% in the absence.

► Ultrasound intensified the releasing of fermentable sugars in the period of constant reaction rate.
► High efficiency of hydrolysis under ultrasound-assisted hydrolysis.
► It was demonstrated that 83% of total fermentable sugar was released in the period of constant reaction rate.
► Ultrasound-assisted acid hydrolysis using phosphoric acid showed to be a promising procedure to be applied industrially for hydrolysis of biomass.