Alkaline hydrogen peroxide-pretreated sugarcane tops for bioethanol production—a process optimization study

In the present work, sugarcane tops (SCT), an agricultural residue, were subjected to alkaline hydrogen peroxide (AHP) subsequently followed by acid hydrolysis for the maximum release of fermentable sugars for bioethanol production. The process parameters that affect the AHP pretreatment efficiency include AHP concentration (%, v/v), SCT loading (%, w/v), pretreatment time (h), pretreatment temperature (°C), and agitation speed (rpm) were studied for effective delignification. Furthermore, central composite design (CCD) based on response surface methodology (RSM) was applied for optimizing various process parameters of acid hydrolysis such as sulfuric acid concentration (%, v/v), reaction time (min), and reaction temperature (°C). The optimal hydrolysis conditions yielded 6.911 g/L of xylose and 4.106 g/L of glucose. The hydrolyzate containing fermentable sugars was fermented using Saccharomyces cerevisiae, and about 9.9 vol% ethanol was obtained at the end of 24 h fermentation. The native, pretreated, and hydrolyzed SCT were also characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques.