Naslov
Inner surface potential measurements and interpretation of equilibrium at electrical interfacial layer

Autori
Preočanin, Tajana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Interfaces against pollution / Puy, Jaume - Lleida : University of LLeida, 2016, 72-72

ISBN
978-84-608-9990-7

Skup
Interfaces against pollution

Mjesto i datum
Lleida, Španjolska, 04.09.2016. - 07.09.2016

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Electrical interfacial layer ; surface charging ; surface potential measurements ; colloid particles

Sažetak
The accumulation and binding of ions at the solid/aqueous electrolyte solution interface is the basis of most surface chemical processes [1]. The electrical charging at a metal oxide surface in aqueous environment, assuming formation of charged surface groups and their partial association with counterions, has been commonly described by the Surface Complexation Model (SCM). According to the SCM the state of charged surface sites is affected by the inner surface potential so that numerous attempts were made to measure this quantity. Experimentally, the construction of single crystal metal oxide and silver halide electrodes has enabled the measurement of open circuit potential and evaluation of the inner surface potential of defined crystal planes [2]. Such experimentally obtained data can be interpreted by the SCM and are in accordance with predictions of the Multi-site Complexation Model. The electrokinetic potential, i. e. potential at the electrokinetic slip plane, of same crystal plane can be obtained via streaming potential (or streaming current) measurements. The comparison and analysis of this two measured potentials leads to interesting and surprising findings. Electrostatic potentials are directly related to binding and distribution of charged ionic species at the interface and this mutual dependency is crucial for understanding the processes at the solid/aqueous electrolyte solution interfaces [3]. For some metal oxide crystal planes the measured surface potential and electrokinetic potential give unexpected results. While the measured inner surface potential is zero, the electrokinetic measurements for the same particular crystal plane provide a higher (absolute) values of the zeta potential. This finding could be explained by considering the pH dependent charging of the interfacial water layer via protonation or deprotonation, resulting in the presence of physically adsorbed hydronium or hydroxide ions. While the pH of the electrolyte solution affects the electrokinetic behavior but not the surface potential, the specific adsorption of strongly bound ions to oxide surfaces affect both the inner surface and zeta-potentials.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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