adsorption of quinoline at the mercury solution interface

Little work has been carried out on the adsorption of quinoline at metal surfaces. Lovercek and Cipris [1] reported that the increase of quinoline concentration in 0.1N - HC1 brought about a decrease in the electro-capillary curves. The study was of a semi-qualitative nature, and no detailed data were given. On the other hand, Bordi and Papeschi [2] examined in detail the adsorption of quinoline on Hg in l.0 M KNO[3], using the electrocapillary technique. Two families of curves representing the lowering in the interfacial tension were given corresponding to two plateaux for the F/c relationship. These were assumed to be due to the adsorption of quinoline in the planer and vertical orientation. Quinoline is frequently used as additive to improve etching and to decrease corrosiveness in Ni electroplating baths [3], and to inhibit the corrosion of Fe by HC1 [4]. Accordingly, a thorough understanding of the factors affecting the adsorption and orientation of this additive at metal interfaces should be of value. In this work, the results of measurements of the parameters of the electrocapillary maximum of mercury, sigma max and E max, are reported for molar aqueous solutions of KNO[3], KCI and HC1 and in 0.5M Na[2]SO containing increasing concentrations of quinoline

Adsorption behaviour of quinolin at the mercury-solution interface II: Measurement of differential capacitance and characteristics of the adsorption isotherms

The adsorption of quinoline at the mercury electrode was studied by Lovercek and Cipris [1] and by Bordi and Papeschi [2]. Differential capacitance measurements [1] in 0.1 N-HC1 produced curves with two minima at c[a]-400 and -900 mV [sec]. The corresponding capacitance values were about 15 and 4 micro F cm [-2], respectively. Adsorption in the anodic potential side was said to be due to influence of the u-electrons, while adsorption on the cathodic side was attributed to the presence of organic cations. Electrocapillary measurements [2] in N-KNO[3] provided information related to the reorientation of the adsorbed molecules. In the present investigation, an attempt is made to study the various factors affecting the adosrption and reorientation of quinoline at the mercury electrode in different electrolytes, with or without specific anion adsorption. The results of differential capacitance measurements were correlated to those previously reported using electrocapillary measurements [3]. Characterization of the adsorption isotherms was also attempted