Anomalous Diffusion of Electrically Neutral Molecules in Charged Nanochannels

Confined and free diffusion of phenol occur in the electric double layer (EDL) and extra‐EDL region in the nanochannels of porous anodic alumina (see picture). The inductive effect of the EDL electric field on the phenol molecules slows their diffusion, but it is negligible in the free‐diffusion region. The extent of the two regions depends on EDL thickness, and hence the diffusion flux increases with increasing ionic strength of the electrolyte.