The effect of speciation on the apparent diffusion coefficient of an ion can be dramatic in a nonreactive porous material. For the systems studied, the effect of concentration was to change the apparent diffusion coefficient by no more than 20 %. By contrast, the effect of speciation on these nonreactive systems studied was to vary the apparent diffusion coefficient by nearly a factor of two at relatively short time. At long time the apparent diffusion coefficient became strongly time-dependent for some species. Such systems cannot be modeled using Fick's law and a constant apparent diffusion coefficient. Further, for one system studied, the apparent diffusion coefficient diverged to infinity, and then became negative for a period of time, due to the diffusion potential. The long time behavior of all the systems studied could be accurately characterized by an electro-diffusion equation containing only two time-independent parameters: the porosity and the formation factor.