A backtitration technique was used to collect proton isotherm data for an Al oxide, and was found to be stoichiometrically related to the cation and anion isotherm behavior. The adsorption of various ions by the Al oxide surface was modeled based on: (i) two surface sites, (ii) pH+salt-dependent reactions (H and Cl~, 2OH~, or Na and OH"), (iii) competitive salt-dependent reactions (Na or Cl~), ...
