Study on the adsorption behaviours of naphthalene on MCM-41 and SBA-15 mesoporous molecular sieves

In this paper, the adsorption behaviours of naphthalene on two popular mesoporous molecular sieves, SBA-15 and MCM-41 were studied. The adsorption isotherms were obtained, and fitted with isotherm models of Langmuir, Freundlich and D-R. The breakthrough curves of naphthalene at different initial concentrations were measured, and well predicted by the constant-pattern wave model. Results show that the Langmuir model can well describe the adsorption isotherms of naphthalene at low concentration with R² higher than 99%. The adsorption ability of SBA-15 with a microporous structure is stronger than that of MCM-41 which contains only mesoporous structures. The predictions on breakthrough curves by the constant-pattern model exhibited higher correlation coefficient for SBA-15 than for MCM-41.The overall mass transfer coefficient K_a of naphthalene on SBA-15 is higher than that on MCM-41, indicating that there is a lower mass transfer resistance and the mass transfer equilibrium can be achieved faster over SBA-15.