The presence of carbon dioxide (CO2) pollutant in the atmosphere has resulted in catastrophic damage to environmental sustainability. Adsorbents such as activated carbon (AC), zeolite, and silica have been studied for the adsorption of CO2,and AC has gained much research traction as AC offers high surface area, high porosity, high removal capacity and fast kinetic in removing pollutants. Biomass wastes are abundant, cheap, and high in carbon content, making them ideal for AC production. Sugarcane bagasse (SB), coconut shell (CS), and empty palm oil fruit bunch (FB) biomass wastes were used to make AC adsorbent in this study. The wastes were converted into carbon through a carbonisation process, followed by chemical activation using triethanolamine (TEA). The physicochemical characteristics of the AC adsorbents were characterised for their surface morphologies, elemental composition, surface area and porosity, and measurement of their effectiveness towards removing CO2gas. The result of characterisation analysis shows AC from SB and CS have excellent pore formation compared to AC from FB on their surfaces. The elemental composition shows AC-CS have the highest surface area of 684.82 m2/g with the highest elemental carbon content of 90.00 among the AC adsorbents. The CO2adsorption measurement shows AC-CS had the highest adsorption capacity of 2.5595 mmol/g, followed by AC-SB (Q = 1.9193 mmol/g) and AC-FB (Q = 1.5745 mmol/g). The high adsorption capacity and excellent physicochemical characteristics of AC-CS indicate promising capabilities of the AC adsorbent for further utilisation in the industrial application of CO2removal. © 2024 Elsevier Ltd. All rights reserved.