Hydronium ions pass through the proton exchange membrane, which is a solid electrolyte in electrochemical cell.
The low Cd biosorption at pH less than 4 has been suggested to the competition among metal ions from
hydronium ions for the available biosorption sites.
No adsorption was observed at low pH values due to opposition of
hydronium ions with the metal ions.
One of the main effects of the medium's pH over the sorption process is related to presence of
hydronium ions which may cause the protonation of the adsorption sites (obviously this process is more evident at low pHs).
At low pH, the surface of the adsorbent was surrounded by
hydronium ions that compete with metal ions, which prevented the metal ions approaching the binding sites on the adsorbent.
These nitrogen radicals then interact with moisture in the atmosphere to create
hydronium ions.
