Preparation of low-cost activated carbons from amazonian nutshells for CO2 storage

Abstract

Low-cost carbonaceous adsorbents with microporous structures and a moderate specific surface area (up to 1630 m2 g−1) were prepared from different amazonian nutshells by one-step chemical activation with KOH for CO2 storage. In-depth micropore structure analysis and surface characterization were performed using adsorption isotherms at 298 K and carbon dioxide isotherms at 273 K. The Brazilian nutshell and Cascara Capuassau exhibit a remarkable CO2 uptake capacity of 5.14 mmol g−1 and 5.13 mmol g−1 at 273 K, respectively up to 1 atm. The highest CO2 adsorption at 298 K equal to 3.67 mmol g−1 was observed on activated carbon produced from Cascara Capuassau. The low-pressure CO2 capacities are well correlated with the volume of small micropores (<0.7 nm) rather than the total micropore volume and surface area. The great mesoporosity of activated carbons is beneficial to ensure higher CO2 capture at high uptake pressure. © 2020 Elsevier Ltd