Temperature Effect on Quinoline Adsorption in Dibenzothiophene Presence Using Mesoporous SBA-15 and Zn/SBA-15 Materials

SBA-15 and Zn/SBA-15 mesoporous materials were synthesized by coprecipitation and incipient impregnation methods, respectively. Both materials were tested as adsorbents of quinoline (Q) adsorption in the presence of dibenzothiophene (DBT), changing temperature and nitrogen concentration. The textural and structural adsorbents results revealed that the Zn incorporation reduced the pore volume and the surface area by 23% and 27%, respectively, compared to the SBA-15 adsorbent. However, both adsorbents presented a hexagonal structure in the form of cylindrical channels of ordered porosity with a domain of (100), (110) and (200) crystalline planes. SEM micrographs of the SBA-15 adsorbent showed rod-shaped particles with 1.20 x 0.65 mu m dimensions. Zn incorporation did not significantly change the final SBA-15 morphology. In general, the Q removal percentage in the presence of DBT for the SBA-15 adsorbent at different nitrogen concentrations was between 10 and 20% higher than for the Zn/SBA-15 adsorbent at 308, 315, 323, and 336 K, associated with the basic nature of Q. However, the highest sulfur removal was observed at 308 K, where the Zn/SBA-15 adsorbent showed 2.5 times more sulfur removal compared to the SBA-15 adsorbent. For both adsorbents, the pseudo second-order kinetic model better fitted the Q adsorption data in the presence of DBT compared to the first-order model. Langmuir and Freundlich models were studied to describe the adsorption parameters of Q at different concentrations and temperatures, the experimental data were adjusted to a Langmuir-type isotherm at temperatures from 308-328 K using mesoporous adsorbents. Additionally, thermodynamic parameters of Q adsorption in the presence of DBT were determined and the parameters like a Gibbs free energy (Delta G0), adsorption enthalpy (Delta H0) and adsorption entropy (Delta S0) were estimated. The results of thermodynamics study and adsorption parameters indicated that the removal of Q in both adsorbents was a spontaneous and exothermic process, and the SBA-15 adsorbent at various nitrogen concentrations and low temperatures obtained high capacities and rates of Q adsorption in DBT presence.Graphical AbstractParticle size distribution and separation factor for SBA-15 and Zn/SBA-15 adsorbents in Quinoline (Q) adsorption as a function of operating temperature.