Effect of Supporting Electrolytes on the Tensammetric Waves of t-Pentyl Alcohol

Abstract

It is widely recognized that supporting electrolyte has an important effect on adsorption, but few syStematie studies have been done hitherto. The authors investigated the effect of supporting electrolyte on the adsorption of organic compounds at electrode. Tensammetriq waves were measured by Yanagimoto Polarograph PA-102, and drop time-potential curves, were used for analyses of the effect.Tensammetric waves of O.05 mol/l of t-pentyl alcohol (constant coneentratlQp). were measured varying the supperting electrolyte conentration. ln such a case, two effects are considered. One is salting out effect which increases the adsorption of organic compounds on electrode. The other is ionic specific adsorption which either reduces the adsorption of organic compounds on electrode or narrows the adsorption potential region-potential region between two adsorption desorption peak, poten-tLigls (E, r, E-p)In the solution of KF or NH2SO4, salting out effect outweighed the other, so that the adsorption potential region and adsorptio:n-desorption peak heights lp, Ip increased with the elevation of electrolyte concentration (Fig. 1, Fig. 2 and Fig. 4). ln the solution of KI or KSCN, ionic specific adsorption outweighed the other, so that the adsorption potential region and peak heights decreased with the elevation of electrolyte concentration (Fig. 5, Fig. 6 and Fig. 7). ln the solution of KCI or KBr, both effects existed. Up to about 1 N solution, ionic specific adsorption narrowed the adsorption potential region (Fig. 8 and Fig.9), while salting out effect increased the surface excess in the adsorption potential region (Fig.10). Above 1 N solution, salting effect outweighed the other and both surface excess and adsorption potential region increased.