Amine-functionalized lignin for CO2 capture. 1: Phenolation- enhanced amine grafting

To address the growing need for the development of a sustainable platform for CO 2 capture, this study investigates the utilization of lignin as a biodegradable support for the fabrication of amine-containing CO 2 adsorbents. The synergetic effect of phenolation followed by the Mannich amination on lignin has been extended to CO 2 adsorption. Lignin was first subjected to phenolation (PL) to enhance its ability for attaching a greater number of amine-containing species. Extensive screening was conducted using five different polyamines to determine the optimum formulation for the Mannich process. The performance of diethylenetriamine-functionalized lignin (AL) and aminated PL (APL) was comprehensively evaluated under various operational conditions, including dry and humid CO 2 environments, different CO 2 concentrations, working temperatures, and cyclic CO 2 adsorption-desorption. In the presence of 15 % CO 2 /N 2 at 25 °C, APL was found to capture more CO 2 compared to AL under both dry and wet conditions, with a maximum CO 2 uptake of 1.45 mmol/g at 35 % relative humidity (RH), representing a 46 % increase compared to dry condition. • Biodegradable lignin was used as a sustainable support for amine-based CO 2 adsorbents. • Lignin was functionalized with five polyamines via Mannich reaction to optimize CO 2 capture performance. • Phenolation improved lignin's capacity to anchor more amine-containing species. • Amine functionalization after lignin phenolation showed superior CO 2 uptake. • Amine-functionalized phenolated lignin exhibited stable cyclic CO 2 adsorption.