CO 2 Capture from Porous Carbons Developed from Olive Pruning Agro-Industrial Residue

Abstract

This work studied the synthesis of activated carbons from olive tree pruning waste since the recovery of this abundant residue for producing activated carbon is a sustainable and environmentally friendly alternative. The physical and KOH-chemical activation processes were compared and analyzed to obtain an appropriate carbon for the adsorption of CO2. Highly microporous carbons were obtained after KOH chemical activation, that exhibit high surface area (3526 m2 g-1), micropore volume (1.20 cm3 g-1), and total volume (1.79 cm3 g-1). The equilibrium and kinetic behaviour of carbons for CO2 adsorption were studied using Langmuir, Freundlich, and Temkin models for the isotherms and pseudo-first order, and pseudo-second-order models for the kinetics. The chemically activated carbon was found to be the most appropriate for CO2 capture at low and high CO2 pressures, showing an adsorption capacity of 5.1 mmol g-1 at 0°C and 1 bar. The estimated isosteric heat indicates that the CO2 adsorption process was feasible and confirms the pure physical adsorption of CO2. The chemically activated carbon allowed ten reuse cycles, maintaining the capture capacity. These results confirm that activated carbons from olive tree pruning residue have a suitable capacity and stability for application as CO2 adsorbents.