Integrated basic treatment of activated carbon for enhanced CO2 selectivity

We attempted the use of three chemical agents viz nitric acid (HN), calcium nitrate (CaN) and calcium ethanoate (CaEt) to achieve enhanced CO2 selective adsorption by activated carbon (AC). In dry phase treatment, microporous coconut shell-based carbon (CS) exhibits higher CO2 capacity than coal-based. However, upon wet-phase pre-treatment, modified CS samples showed lesser CO2 adsorption efficiency. Surface characterization with X-ray photoelectron spectroscopy confirms the presence of calcium and amine species on the samples with integrated treatment (A-CaN). These samples recorded the highest low-level CO2 capture despite calcinated CaEt-doped samples (C-CaEt) showing the highest value for pure and high level CO2 adsorption capacities. The slope and linearity values of isobaric desorption were used to estimate the proportion of CO2 chemisorbed and heterogeneity of the adsorbents’ surfaces respectively. Consequently, integrated basic impregnation provides the most efficient adsorbents for selective adsorption of both indoor and outdoor CO2 levels.