Synthesis and characterization of AFe 2 O 4 (A: Ni, Co, Mg)-silica nanocomposites and their application for the removal of dibenzothiophene (DBT) by an adsorption process: kinetics, isotherms and experimental design.

The kinetics, equilibrium, and statistical aspects of the sulfur removal process from hydrocarbon fuels by AFe 2 O 4 -silica nanocomposites (A: Ni, Mg, and Co) have been investigated in the present study. Nanocomposites were prepared via the auto-combustion sol-gel method and then employed in the adsorptive desulfurization (ADS) process. Next, the prepared samples were characterized by different analytical methods including XRD, SEM, TEM, FT-IR, TGA, and BET. The contributions of conventional parameters including adsorbent dosage and contact time were then studied by central composite design (CCD) under response surface methodology (RSM). Based on the statistical investigations, optimum conditions for ADS were an adsorbent dosage of 7.82 g per 50 ml of the model fuel and a contact time of 32 min. The adsorption amounts reached 38.6 mg g -1 for DBT. The quadratic model was applied for the analysis of variance. Based on the experimental data, the pseudo-first-order (PFO) model could explain the adsorption kinetics of the compounds. Furthermore, the Langmuir isotherm demonstrated considerable agreement with the experimental equilibrium data. According to the results, the NiFe 2 O 4 -SiO 2 nanocomposite showed the best performance compared to other compounds. The sulfur removal efficiency increased from 63 to 94% upon increasing the NiFe 2 O 4 -SiO 2 dosage from 3 to 9 g per 50 ml of the model fuel.