Valorization of coffee grounds into activated carbon using physic—chemical activation by KOH/CO2

Abstract Coffee grounds were employed for the synthesis of activated carbons (ACs) by combined activation with CO 2 and KOH. The influence of CO 2 on the morphological properties and the sorption capacities of adsorbents prepared for phenol (phOH) and methylene blue (MB) was studied. The powders were investigated by infrared spectroscopy, N 2 isotherms and scanning electron microscopy. The activation by KOH under CO 2 flow slightly improves the porous structure (pore volume and specific surface area). The Langmuir isotherm provides a good correlation for both phenol and methylene blue and the adsorption kinetics obey a pseudo-second-order kinetic.