Adsorptive removal of dibenzothiophene from diesel fuel using microwave synthesized carbon nanomaterials

Microwave synthesized carbon nanotube (M-CNT), and carbon nanofiber (M-CNF) were tested for removal of dibenzothiophene (DBT) from a model diesel fuel (MDF) by adsorption process. M-CNT showed relatively higher DBT removal capacity over M-CNF. The maximum DBT adsorption by M-CNT and M-CNF were 43% and 35%, respectively, for an adsorption condition of 0.25 g of adsorbent, 250 mg/l of DBT in MDF, 30 degrees C, 60 min and 250 rpm. The Sips and Freundlich adsorption isotherm models were used to correlate the adsorption equilibrium experimental results of DBT on M-CNT and M-CNF. The negative values of Delta G degrees, Delta H degrees, and Delta S degrees from the thermodynamic studies confirm the spontaneity and feasibility of the system, exothermic nature and non-random behavior of DBT molecule on M-CNT respectively. The adsorption kinetic results show that the adsorption systems of DBT-M-CNT and DBT-M-CNF obey the pseudo-second order and pseudo-first order kinetic model, respectively. Further it was also found that the surface diffusion is the rate controlling step for DBT adsorption on both M-CNT and M-CNF.