Comparative Study of Three Chemical Pretreatments and Their Effects on the Structural Changes of Rice Straw and Butanol Production

Abstract

In this study, the optimal conditions for the ionic liquid pretreatment of rice straw by microwave irradiation was identified by Response Surface Methodology (RSM). The maximum level of sugar concentration of 19.59 g/L was derived when rice straw was pretreated at 162 °C for 48 min and further hydrolyzed by enzymatic saccharification. The comparison of chemical pretreatment was performed using ionic liquid, alkaline, and acid to evaluate the effectiveness and effect structural changes of rice straw. Nevertheless, the total sugar yield from this ionic liquid pretreatment was 13% lower than alkaline (NaOH) pretreatment. All hydrolysates from chemical pretreatment were subjected for use as a culture medium for Clostridium beijerinckii TISTR 1461 in acetone–butanol–ethanol (ABE) fermentation. The results suggested that residue ionic liquid affects microbial growth, so a detoxification step was cautiously considered. Additionally, using hydrolysate of the rice straw pretreated by NaOH as a substrate, isobutyraldehyde was found in the fermentation broth, suggesting that C. beijerinckii TISTR 1461 can produce isobutanol in proper conditions. © 2019, Springer Nature B.V.