Green chemistry design of one-step extraction of multi-functionalized lignin-precursors directly from biomass

Abstract

The reliance on non-renewable fossil fuel-based polymers presents significant environmental and humanitarian challenges, including climate change and pollution. Urgent replacement with sustainable alternatives is imperative to mitigate these issues and ensure a carbon-neutral footprint. Lignocellulose, derived from biomass, emerges as a promising substitute due to its abundance and non-edible nature. Comprising lignin, cellulose, and hemicellulose, lignocellulose offers a structural basis for plant biomass, with lignin particularly standing out for its unique properties such as mechanical strength and rigidity due to its aromatic backbone. Despite its potential, effective valorization of lignin remains limited, with a significant portion still used primarily as a fuel source due to its heterogeneity and extensive condensation of lignin structure during existing pulping processes. This study aims to address this challenge by developing a one-step process for synthesizing multi-functionalized lignin precursors directly from biomass, aligning with green chemistry principles. By utilizing lignin as a biobased alternative and implementing a one-step process, this study aims to enhance the sustainability of polymer production while minimizing waste and eliminating the use of toxic chemicals. The novelty of the current study involves sourcing reactants from renewable resources and employing organic carbonates and organic acids to alter lignin's chemistry during extraction, paving the way for a safer and more sustainable synthesis of multi-functionalized precursors in one-step from biomass. This study also includes an environmental impact analysis and industrial scalability assessment of the one-step lignin extraction process. The analysis compares the environmental footprint of the one-step process with conventional methods like Kraft and Organosolv pulping, as well as sustainable methods such as Gamma-Valerolactone (GVL) and Deep Eutectic Solvent (DES) extraction. Key metrics such as the Waste E factor and Greenhouse Gas (GHG) emissions are calculated to evaluate waste and carbon emissions. Additionally, the scalability assessment explores the feasibility of implementing the one-step process at an industrial scale, focusing on efficiency, cost, and sustainability.