Calorimetric study of activated carbons impregnated with CaCl2

Abstract

Activated carbon monoliths with different surface characteristics were prepared by impregnating oil palm stone with diluted aqueous CaCl2 solutions (with concentrations between 2 and 7% w/v) without binders. The solids were characterized by determination of nitrogen adsorption isotherms at 77 K and carbon dioxide adsorption isotherms at 273 K using volumetric adsorption equipment. Surface area and micropore volume values were calculated from the nitrogen isotherms using the BET and DR models, respectively, obtaining solids with low percentages of mesoporosity. Immersion enthalpies of the activated carbon monoliths were determined in benzene, with values between -173 and -104 J g-1, and water, with values between 61 and 30 J g-1, indicating that the monoliths have a hydrophobic character.