One-Pot Electrocatalytic Lignin Depolymerization with In-Situ Extraction: A Feasible Approach Toward Biomass-Based Oils

Abstract

This investigation presents a one-pot electrochemical depolymerization of lignin, coupled with in-situ extraction, to enhance product recovery and process efficiency. Kraft lignin was dissolved in an aqueous sodium carbonate solution and covered with a methyl isobutyl ketone (MIBK) layer. The electrocatalytic reaction, conducted at −350 mA, facilitated lignin depolymerization, yielding a lignin-based bio-oil (LO) composed of a mixture of aromatic compounds, smaller aliphatic molecules such as alcohols, ketones, and acids, as well as sugar derivatives. Size exclusion chromatography confirmed a substantial reduction in molecular and dispersity, indicating effective and controlled lignin depolymerization. MIBK was chosen as an effective solvent for in-situ extraction due to its proven efficacy, reusability, and compliance with sustainable solvent guidelines. Preliminary tribological assessments demonstrated that, despite a higher coefficient of friction (COF) compared to conventional ester oils, LO provided comparable wear resistance, with minimal surface damage observed. Wear imaging further revealed stronger, more resilient surface interactions, suggesting LO’s potential as an eco-friendly lubricant with enhanced durability. These findings mark a critical advancement in lignin valorization, successfully overcoming challenges in product recovery from depolymerization processes and demonstrating its viability as a sustainable alternative to petroleum-based lubricants. Future studies will focus on optimizing formulation and fine-tuning performance to expand LO’s application potential in industrial lubrication.