Characterisation of granular activated carbon prepared by activation with CaCl2 by means of gas adsorption and immersion calorimetry

The textural characteristics of granular activated carbons obtained by chemical activation of African palm stone with CaCl2 were established with nitrogen adsorption at 77 K, carbon dioxide adsorption at 273 K, and immersion calorimetry in benzene. A comparison was made between the fit of N-2 adsorption experimental data with the calculated isotherms using two models: non-local density functional theory and quenched solid density functional theory. The calorimetric technique allowed measurement of the immersion enthalpies in benzene and subsequent calculation of the accessible areas of the carbons. A correlation was established between the enthalpic parameters and it was found that immersion enthalpy in benzene increased with the increasing surface area and pore volume of the carbons. Also the samples were characterized chemically using Boehm titrations.