Synthesis of cerium oxide-magnesium oxide adsorbent using egg-shell membrane bio-templating for carbon dioxide capture

Abstract

Increased CO2 atmospheric concentration is majorly contributed by the uncontrolled greenhouse gasses emission from rapid industrialisation. This phenomenon could lead to irreversible environmental problems such as climate change, global warming, ocean acidification and other environmental related issues. Thus, to keep this under control, several approaches have been proposed and conducted. Currently, carbon capture via metal oxide solid adsorbent adsorption is one of the approaches that is progressively studied. However, commercialised metal oxide adsorbents such as magnesium oxide (MgO) and cerium oxide (CeO2) have several drawbacks such as poor structural and textural properties and low surface basicity, leading to low CO2 adsorption. Therefore, the purpose of this study was to prepare mesoporous composite CeO2-MgO (CM-BT) adsorbent via the utilisation of egg-shell membrane (ESM) as a template. The prepared adsorbents were characterised using field emission scanning electron microscopy-energy dispersion X-ray spectroscopy, transmission electron microscopy-energy dispersion X-ray spectroscopy, X-ray diffraction, nitrogen (N2) physisorption, Fourier-transform infrared spectroscopy, thermogravimetric analysis and CO2-temperature-programmed desorption (CO2-TPD). The CO2 uptake performance was evaluated at 1 atm and 300 K. It was found that mesoporous CM-BT adsorbent exhibited an enhancement in structural properties, with higher surface area (42 m2/g) and pore volume (0.185 cm3/g) compared to composite CeO2-MgO prepared via thermal decomposition (CM-TD). CM-BT exhibited a high CO2 uptake capacity of 5.7 mmol/g, which was 2.5-times higher than CM-TD. This was due to the increased surface basicity of CM-BT, which was associated with abundant adsorption sites of weak, medium and strong base-site. This study revealed that ESM bio-templating is a promising approach in synthesising mesoporous material adsorbent with enhanced adsorbent's physicochemical properties, resulting in increased CO2 uptake capacity.