Adsorption behaviour of dihydrogen phosphate ions on mercury from constant ionic strength solutions

✍ Scribed by E.R. Gonzalez; A. Carubelli; S. Srinivasan

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 661 KB
• Volume: 30
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(85)80081-5

✦ Synopsis

The adsorption bhaviour of &PO; anions on mercury has previously been analysed from capacitance-potential relations at the interface of mercury with K&PO,. It is not possible to determine unambiguously the adsorption characteristics of I&PO, ions from siagle salt solution experiments because of the possible existence of a layer of water molecules between the elecmxle and the adsorbed ions. In this work, the adsorption behavior of H*PO; ions on mercury is analysed from experimental measurements of the capacitance as a function of potential at the interface of mercury with constant ionic strength solutions of compositions x M KH,PO, -t (1 -x) M KF. It is shown that the Qlculated amounts of adsorbed ions do not depend on the position of these ions relative to the solvent molecules. The double layer parameters were calculated taking into account the variations of activity coefficients of KH,PO, and KF with solution composition. In constant ionic strength solutions, the plot of adsorbed charge vs &&rode charge exhibits a maximum due to competition between the adsorbed H,PO; anions with the solvent or other ionic species. This result is shown to be important in determining the properties of the double layer characteristics in the presence of adsorbed H,PO; ions.