With the aim to investigate how the diffusion of the MB
molecules onto ACb takes place, the intraparticle diffusion model
proposed by Weber and Morris [45] was applied. The qt versus t0.5
plots, for all studied concentrations, are shown in Fig. 6 and the
obtained parameters are listed in Table 5. The straight line slope
gives the value of intraparticle diffusion constant, kdi, while the
intercept corresponds to the approximate value of boundary layer
thickness, Ci.