Silver Ion Response as a Test for the Multilayer Model of Glass Electrodes

✍ Scribed by A. A. Belyustin

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 141 KB
• Volume: 11
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/(sici)1521-4109(199907)11:10/11<799::aid-elan799>3.0.co;2-x

✦ Synopsis

The model of an inhomogeneous altered surface layer of the glass, formed due to its interaction with water solutions containing potentialdetermining ions, is presented. An ion interdiffusion over sublayers involves the appearance of some quasi-steady state potential levels of the glass electrodes (GEs) which correspond to a local equilibrium at intermediate boundaries between sublayers. When the interdiffusion reaches the sublayer being transient to the glass bulk, the steady state potential is established. We studied the GE potential dynamics and the composition of surface layers of some alkali aluminosilicate glasses after transfer of the GEs from HNO 3 or MeNO 3 solution into AgNO 3 solution and vice versa. A great selectivity to the Ag ion was found. When the direction of the exchange was Me 3 Ag , the steady state was reached in a few hours; at the inverse direction this took days and even months for H ion. At an intermediate time the potential changes or quasi-steady state potential levels were observed. The dynamics of GEs potentials correlated with the changes in the ionic composition of the glass surface layers.