Integrated biorefinery routes to transform furfural waste into 2G biofuels and PFOA-adsorbing biochar

Abstract

This study presents a cutting-edge decentralized biorefinery approach that valorizes furfural residues (FRs) into high-value products, including ethanol, bio-oil (emphasizing bio-phenols), and perfluorooctanoic acid (PFOA)-adsorbing biochar. Employing an advanced acid/glycerol pretreatment with fatty alcohol polyoxyethylene ether (AEO), surfactant significantly enhances FR fractionation of FRs. The AEO plays a crucial role in pretreatment by weakening cellulose-lignin interactions, enhancing pore characteristics, and preventing pseudo-lignin formation in FRs. These modifications increase cellulose hydrolysis efficiency, facilitating the conversion of cellulose-rich residues into 198 g kg⁻¹ ethanol through hydrolysis and fermentation. The remaining lignin undergoes pyrolysis, producing 184 g kg⁻¹ bio-oil, with a phenol content of 77.5% and 237 g kg⁻¹ biochar. The biochar's potential for adsorbing PFOA is evaluated, costing just 1.5–1.8 cents per gram, offering a sustainable method for environmental remediation. Detailed physicochemical and computational analyses reveal that PFOA adsorption on biochar surfaces involves electrostatic interactions, hydrogen bonding, and hydrophobic interactions. The study further evaluates this approach's economic and environmental viability, highlighting a minimum biochar selling price of US$ 41.81 per ton FRs and CO₂ emissions of 936 g CO₂ per kg biochar. This research reaffirms the potential of FRs as a sustainable feedstock for biofuel and bioproduct production, advancing circular bioeconomy principles.