Monolithic, hybrid and particulate lignin-based hydrogels for sustainable CO2 capture†

Abstract

Amine-infused hydrogels (AIHs) represent a promising platform for developing solid absorbents with improved CO₂ absorption capacity. However, most of them rely on petroleum-based and toxic monomers. Lignin nanoparticles (LNPs) are becoming prominent players at the interface between sustainable nanomaterials technology and chemical science due to their high surface-area-to-mass ratio, which allows them to interact with multiple active compounds. Capitalizing on this spherical morphology and high surface area, the present work presents a strategy to prepare hybrid and particulate lignin-based hydrogels that can act as amine carriers for CO₂ capture. The entire process is based on the internal stabilization of LNPs via intraparticle cross-linking process and subsequent base-catalyzed ring-opening reaction between LNPs and poly(ethylene glycol) diglycidyl ether in aqueous media. Upon swelling the hydrogel with an amine solution, hybrid and particulate lignin-based AIHs rapidly capture CO₂ with a higher overall uptake compared to commonly used aqueous amine solutions under similar experimental conditions, while also stand and in some cases surpass the performance of other AIHs reported in the literature. Additionally, these new materials can be easily regenerated multiple times with minimal decrease in CO₂ absorption capacity, demonstrating their potential application in decarbonization capture technologies.