Biphasic Approach for Bioethanol Production: Simultaneous Oxalic Acid Pretreatment, Saccharification, and Co‐Fermentation.

The physiochemical pretreatment was performed using different concentrations of oxalic acid (OA) as a simultaneous pretreatment and saccharification (SPS) process on rice straw to obtain reducing sugar from two‐phasic SPS process using enzymatic and acidic hydrolysis to subsequently ferment to bioethanol in order to maximize the yield of bioethanol. The optimal condition for pretreating rice straw using 0.5, 0.75, 1, and 1.5 M OA at 120°C for 1 h was evaluated. The morphological and structural changes after simultaneous pretreatment and SPS process were evaluated using Fourier‐transform infrared (FTIR), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and field‐emission scanning electron microscopy (FESEM) analysis. It was evaluated that optimum pretreatment conditions using a lesser concentration of OA had resulted in 30.37% of xylan removal from pretreated rice straw obtained after simultaneous pretreatment and SPS process. The ethanol production yield ranged from 0.42 to 0.37 g/g with fermentation efficiency of up to 57.18% and an overall ethanol production yield of 42.84% from the obtained hydrolysate of the two‐phasic SPS process. The highest ethanol concentration from the obtained hydrolysate was produced at 120°C for 1 h with 0.75 M OA; under this condition, maximum degradation of utilized lignocellulosic biomass takes place. [ABSTRACT FROM AUTHOR]