Adsorption of Dibenzothiophene (DBT) on Activated Carbon from Dates’ Stones Using Phosphoric Acid (H3PO4)

Samples of Granular Activated Carbon (GAC) were produced from dates stones by chemical activation using phosphoric acid (H3PO4) as an activator. Textural characteristics of GAC were determined by nitrogen adsorption at 77 K along with application of BET equation (Brunauer, Emmett and Teller) for determination of surface area. Pore size distribution and pore volumes were computed from N2 adsorption data by applying the non localized density function theory (NLDFT). GAC samples were used in desulfurization of a model diesel fuel composed of n-decane (n-C10H22) and dibenzothiophene (DBT) as sulfur containing compound. The adsorption data were fitted to both Freundlich and Langmuir models with better predictions using Freundlich model. The optimum operating conditions for GAC preparation based on high adsorption capacity are Tcarb = 600ºC, θcarb = 3.0 hours and solid to activator weight ratio, R = 2.0 with adsorption capacity of 41.32 mg S/g of dry GAC. Finally, linear regression was done for the average pore diameter and the experimental data of micropore volume divided by the surface area using carbon slit pore model. The resulted linear empirical equation predicts reasonably the critical pore size diameter of DBT at which adsorption is hindered.