Electrosorption of tri(n)octylphosphine oxide from methanol and water-methanolic solutions on a polarized mercury electrode

✍ Scribed by A. Pappa-Louisi; P. Nikitas; D. Jannakoudakis

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 391 KB
• Volume: 29
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(84)87102-9

✦ Synopsis

The adsorption of tri(n)octyIphosphine oxide on the mercury electrode in methanolic and water-methanolic solutions of LiCl has been examined from electrocapillary measurements. In methanolic solutions this substance shows the typical characteristic f-turns of an organicadsorbate.

The isotherms are congruent only with respect to potential on the negative side of the electroeapillary maximum and in this region a Frumkin isotherm is obeyed with an interaction parameter equal to Q = 0.3 corresponding to intermolecular attraction. On the positive side the isotherms are non congruent with respect to both the electrical variables, while the system may be described by a Frumkin isotherm either with constant I-, = 1.03

x lO_" mole cm-' and 01 decreasing with the increase of the positive charges on the electrode or with constant LY = 0.3 and decreasing I-,.

In water-methanolic solutions the adsorption of tri(n)octylphosphine oxide increases, due mainly to the decrease of its solubility. In parallel a clear dependence of r, on the amount of water in solutions is detected. r, is seen to increase with the water content of the solutions probably due to a partial overlap of the hydrocarbon chains of this substance.