Time dependent interfacial behaviour of tributylphosphine oxide at the mercury-solution interface

Abstract

A series of methods are used for the quantitative description of the time dependent interfacial behaviour of tributylphosphine oxide (TBPO). These methods include measurements of the interfacial tension by a capillary electrometer as well as differential capacitance measurements with a dropping mercury electrode (D.M.E.) of short drop times (⪬5 s), a D.M.E. of large drop times (~20 s) and a hanging mercury drop electrode (H.M.D.E.). The capacitance measurements with large drop times reveal the existence of peculiarities during the development of the adsorption film. The adsorption equilibrium of TBPO, at the vicinity of the adsorption maximum, is generally established within times shorter than 10 s. At the region of the adsorption pseudocapacity, time intervals ranging from 200 to 400 seconds are required for the equilibrium. The adsorption parameters derived with the large drop time D.M.E., are in reasonable agreement with those obtained by electrocapillary measurements.