Improved bioethanol production from corn stover by alkali pretreatment with a novel pilot-scale continuous microwave irradiation reactor

A novel continuous microwave irradiation (MWI) pilot-scale reactor was designed specifically for biomass pretreatment. To test the efficiency of this reactor, MWI-assisted alkali pretreatment of corn straw (CS) was investigated using a central composite design for the response surface methodology. With a processing capacity of 0.28 kg CS (dry matter, DM)/h, the optimal conditions were as follows: 4.50 kW, 30 min, and 3.50% NaOH (w/v). The glucose and ethanol production from the pretreated CS were 63.22 and 31.29 g/100 g DM, respectively. These values were 4.42 and 3.79 times higher, respectively, than those from untreated CS. Structural changes in the untreated/pretreated CS were identified by analyzing its chemical composition using X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). In addition, the solid residue recovery ratio was demonstrated to be an indicator of the biomass bioconversion potential.