An investigation of anomalous time-fractional diffusion of isopropyl alcohol in mesoporous silica

Anomalous behavior of Isopropyl alcohol transport in mesoporous silica is experimentally and theoretically investigated. Fitting of the experimental data by the solutions of the second Fick's law with various pore geometries shows no coincidence between the experimental data and theoretical curves. We demonstrate that experimental data are in an excellent correspondence with the solution of the time-fractional diffusion equation with fractional order value ranging from 1.07 to 1.3, obtained for boundary conditions that correspond to the experimental conditions. These findings reveal that isopropyl alcohol in mesoporous silica may exhibit anomalous mass transfer behavior because of geometrical restrictions of silica pores.