Optimizing corncob pretreatment with eco-friendly deep eutectic solvents to enhance lignin extraction and cellulose-to-glucose conversion

Author(s)

Rodrigues, Bruna Green ; Jose, Alvaro H. M. ; Prado, Carina Aline ; Rodrigues Jr, Durval ; Rodrigues, Rita C. L. B.

• Document type: Journal article
• Source: International Journal of Biological Macromolecules; v. 283, p. 12-pg., 2024-12-01.

Abstract

Deep eutectic solvents (DES) are an eco-friendly, cost-effective alternative to traditional ionic liquids for biomass pretreatment, with unique characteristics encompassed by hydrogen bond donor (HBD), the molar ratio of hydrogen bond acceptor (HBA) to HBD, temperature, and time affecting efficiency. Despite its potential, a comprehensive study exploring the interplay of these factors is limited. This study explores the optimization of pretreatment variables using choline chloride/lactic acid (1:5) via the response surface method (RSM). It aims to evaluate the effects of time and temperature on lignin extraction, cellulose-to-glucose conversion, and hemicellulose removal. Employing a 22 central composite design with temperature (80-140 degrees C) and time (2-6 h) as variables, optimal conditions were 123 degrees C for 6 h. Results include 90.08+1.42 % lignin extraction, 68.77+6.9 % cellulose-to-glucose conversion, and 77.34+0.85 % hemicellulose removal, with 52.52+8.07 % lignin recovery. The fractions of pretreated CC and lignin recovered in the optimal condition found were characterized by X-ray diffraction (XDR), Fourier transform infrared spectroscopy (FTIR), 1 H, 13 C, 2D-HSQC NMR spectroscopy, Thermogravimetric analysis (TGA/DTG), Gel Permeation Chromatography (GPC) to elucidate chemical characteristics of the materials obtained and facilitate downstream valorization. High efficiency was achieved in lignin extraction and cellulose conversion, and addressing solvent viscosity and DES recycling will further enhance the potential for industrial scalability. (AU)

• FAPESP's process: 22/03904-7 - Obtaining renewable chemicals by valuing sustainable carbon from corncobs
• Grantee: Rita de Cássia Lacerda Brambilla Rodrigues
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Regular Program Grants