Enhancing enzymatic hydrolysis of waste sunflower straw by clean hydrothermal pretreatment

Hydrothermal pretreatment is an effective way to change the lignocellulose structure and improve its sacchar-ification. An efficient hydrothermal pretreatment of sunflower straw was conducted when the severity factor (LogR0) was 4.1. 58.8% of xylan and 33.5% of lignin were removed at 180 degrees C for 120 min with a solid-to-liquid ratio of 1:15. A series of characterizations (such as X-ray diffraction, Fourier Transform infrared spectroscopy, scanning electron microscopy, chemical component analysis, cellulase accessibility) proved that hydrothermal pretreatment destroyed sunflower straw surface structure, enlarged its pores, and enhanced the accessibility to cellulase (371.2 mg/g). After the enzymatic saccharification of treated sunflower straw for 72 h, 68.0% yield of reducing sugar and 61.8% yield of glucose were achieved, and 3.2 g/L xylo-oligosaccharide was obtained in the filtrate. Overall, this easy-to-operate and green hydrothermal pretreatment could effectively destroy the surface barrier of lignocellulose, help remove lignin and xylan, and increase the enzymatic hydrolysis efficiency.

Automated summary

Hydrothermal pretreatment is an effective method to improve the saccharification of lignocellulose. In this study, an efficient hydrothermal pretreatment of sunflower straw was conducted, resulting in the removal of 58.8% xylan and 33.5% lignin at a treatment temperature of 180 degrees C for 120 min and a solid-to-liquid ratio of 1:15. Various characterizations confirmed that hydrothermal pretreatment altered the surface structure and increased the accessibility to cellulase. The enzymatic saccharification of the treated sunflower straw achieved a high yield of reducing sugar and glucose and also produced xylo-oligosaccharide in the filtrate.