Enhancement of lignin removal and enzymolysis of sugarcane bagasse by ultrasound-assisted ethanol synergized deep eutectic solvent pretreatment

A low-cost and green biorefinery will increase the economy and revenue from lignocellulosic biomass. This study demonstrated the effect of two-pot sequential pretreatment, comprising of ultrasound ethanol (USEL) synergized ternary deep eutectic solvent (TDES, choline chloride: glycerol: FeCl3 center dot 6H(2)O), with the aim to investigate the effects of USEL, TDES, and USEL thorn TDES pretreatments on enhancing delignification of sugarcane bagasse (SCB). The results showed that under the optimum TDES pretreatment conditions (FeCl3 center dot 6H(2)O, 120 degrees C, 3 h), the cellulose content and lignin removal rate (LRR) of SCB reached 47.67 and 82.71%, respectively. Under the optimum synergy conditions (USEL conditions: 100% ethanol, 20 + 28 + 40 kHz, 240 W, 60 min; TDES conditions: FeCl3 center dot 6H(2)O, 120 degrees C, 3 h), the cellulose content and LRR of SCB reached 66.17 and 86.39%, respectively. After enzymatic hydrolysis, the SCB pretreated with USEL + TDES shows a saccharification rate of 90.31%, which was substantially higher than that of the SCB pretreated with TDES alone (85.68%). X-ray diffraction, particle size, brunaueremmet-teller, scanning electron microscopy, and optical microscopy analyses were conducted to confirm the efficiency of USEL + TDES on pretreating SCB. Meanwhile, 2D-HSQC NMR analysis revealed that regenerated lignin exhibited well-preserved structures (beta-O-4, beta-beta linkages), making it suitable for depolymerization into monoaromatic compounds. Overall, this work demonstrated that biomass pretreatment with the USEL + TDES was promising for a low-cost biorefinery to efficiently fractionate lignocellulosic biomass into glucose and high-quality lignin with tailored chemical structures. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study demonstrated that the sequential pretreatment of ultrasound ethanol and ternary deep eutectic solvent effectively enhanced delignification and saccharification of sugarcane bagasse, showing promise for low-cost biorefinery development.