Polarographic study of the interaction between humic acids and other surface-active organics in river waters

The surface activity of river water humic acids (HA) has been studied using the principle of suppression of polarographic streaming maxima by organics that adsorb on the mercury electrode. HA isolated from river water by hydrophobic adsorption onto Amberlite XAD-2 were found to be almost four times more effective at maximum suppression than natural river water organics as a whole. Ultraviolet and fluorescence measurements indicated that 25–30% of total dissolved organics were in the hydrophobic HA fraction. HA's were found to interact interfacially with other more hydrophilic organic components with a 50% decrease in their surface activity. Similar interactions were found with synthetic surface-active materials.