Amine-Functionalized Clays as Solid Sorbents: High-Pressure CO₂ Sorption Testing and Characterization

In this work, the CO₂ sorption capacity of both raw and amine-functionalized clays was investigated. For this purpose, samples of clay-based materials intended for industrial and artisanal applications were collected in the province of Imbabura, Ecuador. These raw materials were functionalized with monoethanolamine (MEA) and ethylenediamine (EDA) mixtures to enhance the affinity for carbon dioxide. CO₂ sorption testing was conducted in a high pressure, nonstirred system with an initial pressure of 3550 kPa and room temperature (25 °C). CO₂ sorption capacity was quantified by monitoring the pressure drop resulting from CO₂ uptake. Comprehensive characterization of the clay-based materials was carried out using nitrogen physisorption analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray fluorescence (XRF) to determine the textural properties, crystalline phases, physicochemical properties, and functional groups present in the samples. The results demonstrated that amine-functionalized clays exhibited higher CO₂ sorption capacity, with improvements of up to 442.85% compared to raw materials. Notably, the amine-functionalized clays intended for artisanal usage achieved a maximum capacity of 3.125 mmol CO₂/g. These findings confirmed that amine functionalization favors CO₂ capture, offering a viable and scalable alternative to mitigate the impacts of the rising atmospheric CO₂ emissions.