Olive Mill Waste-Derived Activated Carbon for CO<sub>2</sub> Capture Using Realistic Conditions
Pamela B. Ramos, Arminda Mamaní, Fabiana Sardella, Amaya Arencibia, R. Sanz, Eloy S. Sanz-Pérez, Marcela A. Bavio, María Erans
Abstract
Olive mill waste (OMW) is a solid residue largely generated in the production of olive oil, whose haphazard dumping causes soil and water contamination due to its high content of organic compounds and characteristic acidic nature. This agroindustrial waste source can be used as a potential sustainable precursor for the production of activated carbon that can be used as an outstanding sorbent for CO 2 capture. In this work, OMW was utilized as the activated carbon precursor, and KOH was used as the activating agent. Activation temperature, time, and KOH/carbon ratio were investigated in order to produce suitable activated carbons for CO 2 capture. Textural and chemical characterizations were made by scanning electron microscopy (SEM), adsorption–desorption N 2 isotherms at 77K and CO 2 isotherms at 273 K, and Fourier transform infrared spectroscopy (FTIR). CO 2 adsorption isotherms between 0 and 6 bar at 25 °C were obtained, and CO 2 uptake was also measured at 30 °C in 100 mL/min of 15% vol CO 2 for 180 min. The adsorption kinetic curves were fitted with pseudo-first-order (PFO) and pseudo-second-order (PSO) models. Also, the cyclic performance of the best adsorbent was explored for 10 adsorption/desorption cycles. The highest CO 2 uptake was observed for the activated carbon synthesized with a KOH/precursor ratio of 2:1 and activated at 650 °C for 45 min, which had a CO 2 uptake of 105.7 mg/g (2.4 mmol/g) in pure CO 2 and 37.2 mg/g (0.84 mmol/g) in 15% vol CO 2, as measured in a TGA at 30 °C.