Effects of Modified Activated Carbon on Microwave-Accelerated Organosolv Fractionation of Rice Husk

Abstract

Organosolv fractionation is a promising approach for the separation of lignocellulosic components in integrated biorefineries where each component can be fully valorized into valuable platform chemicals and biofuels. In this study, microwaveaccelerated organosolv fractionation was developed for the modification of lignocellulosic fractionation of rice husk. The fractionation condition was optimized for 1 h with the microwave irradiation at 300 W using a ternary solvent mixture composed of 24%:32%:44% water/ethanol/methyl isobutyl ketone. The effects of mineral acids (HCl, H 3 PO 4 , and H 2 SO 4 ) and heterogeneous acid promoters (HCl, H 3 PO 4 , and H 2 SO 4 impregnated over activated carbon) on the efficiency and selectivity of product yields (i.e., glucan, hemicellulose-derived products, and lignin) were also investigated. It was found that the use of H 3 PO 4 −activated carbon as the promoter showed superior performance on the fractionation of rice husk components, resulting in 88.8% recovery of cellulose, with 63.8% purity in the solid phase, whereas the recovery of hemicellulose (66.4%) with the lowest formation of furan and 5-hydroxymethyl furfural and lignin (81.0%) without sugar cross-contamination was obtained in the aqueous ethanol phase and organic phase, respectively. In addition, the morphology structure of fractionated rice husk presented 2.6-fold higher surface area (5.4 m 2 /g) of cellulose-enriched fraction in comparison with the native rice husk (2.1 m 2 /g), indicating the improvement of enzyme accessibility. Besides, the chemical changes of isolated lignin were also investigated by Fourier-transform infrared spectroscopy. This work gives pieces of information into the efficiencies of the microwave strategy as a climate neighborly elective fractionation method for this serious starting material in the biotreatment facility business.

Mitigating biomass recalcitrance for plant‐based bioenergy production

“…9 An estimated 10 metric tons of feedstock is produced per hectare annually, suggesting that its abundant availability could make it feasible for meeting global renewable energy demands. 4,10,11 Notwithstanding the availability and potential of lignocellulosic materials for bioenergy and other industrial applications, their composition and network structure in SCW impede digestibility through chemical or enzymatic methods. The lignocellulosic barrier is estimated to impede biomass conversion by 20% or more; therefore, the corresponding production cost increases by nearly 20%-30%.…”