The porous and hydrated structure of hydrogels corresponds to the convection and diffusion mass transport of solutes through the hierarchical structure of hydrogels that include free spaces at different length scales, i.e. from (sub)nano to microscale . Different theoretical models, such as the hydrodynamic theory, free volume and the obstruction theory have been developed to predict diffusivity in hydrogels, but with limited success . The chemical structure of polymers constructing the HMs and the nature and density of crosslinking agents can significantly affect the diffusion and equilibrium adsorption of analytes.