ADSORPTION OF AMINES ON A DROPPING MERCURY-ELECTRODE

Adsorption of hexamethylenetetramine (HMTA), triethanolamine (TEA) and triethylenetetramine (TETA) on a dropping mercury electrode has been studied by the electrocapillary curve method, the tensammetry and the impedance-bridge method. The potential ranges of adsorption were from 0 V to - 1.50 V for HMTA, from 0 V to - 1.40 V for TEA and from 0 V to - 1.75 V for TETA, respectively (0.1 mol/dm3). Adsorptive force was stronger in the order of HMTA < TEA < TETA. In the low concentration ranges, the adsorption of TEA and TETA obeyed the Langmuir isotherm. On the other hand, in the high concentration ranges, the adsorption of TEA and TETA did not obey the Langmuir isotherm, and the parameter ''a'' which is a quantity characterizing the interaction between the adsorbed species in the Frumkin isotherm were negative values, indicating that repulsive forces act between the adsorbed species. Further, the adsorption of HMTA did not obey the Langmuir isotherm and ''a'' was a negative value of about - 1.2.