HEMA-based macro and microporous materials for CO2 capture

Abstract

New polymeric macroporous materials based on poly 2-hydroxyethyl methacrylate (pHEMA) were synthesized and tested to adsorb CO2. To this purpose, bio and affordable amine-based molecules such as lysine (LYS) and histidine (HIS) were selected as CO2 active sites and used to functionalize HEMA monomer before its crosslinking polymerization. The as-prepared monomers and polymers were characterized by using Nuclear Magnetic Resonance (NMR), Fourier Infrared Spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX). Compared to materials reported in the recent literature, all produced ones provide exceptional adsorption capacity in the 162–193 ppm range. In particular, H-HEMA-LYS exhibits the best adsorption grade, well-fitting the Linear Driving Force (LFD) model. H-HEMA-LYS reusability was also tested for up to 5 cycles without significant loss in capture performance. Finally, to get insight into the role of morphology in CO2 adsorption, two diverse macroporous structures were synthesized (hydrogels and cryogels) for both HIS and LYS-based materials. As it turns out, hydrogel formulations of an average area ranging from 15.5 to 230 μm2 adsorb 12% more than cryogels with higher values (266–605 μm2).