Naslov
Surface Potential at TiO2-Aqueous Electrolyte Solution Interface

Autori
Preočanin, Tajana ; Kallay, Nikola

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

Izvornik
19th Conference of the European Colloid and Interface Societ, Book of abstracts / - : Group of Macromolecular and Colloid Chemistry, The Norwegian Chemical Society, University of Oslo, 2005

Skup
19th Conference of the European Colloid and Interface Society

Mjesto i datum
Geilo, Norveška, 18.09.2005. - 23.09.2005

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
-

Sažetak
The rutile and anatase electrodes, made of monocrystal, were used to measure the potential at the inner Helmholtz plane (surface potential phi0) as a function of pH. The ionic strengths (0.1 mol dm-3, 0.01 mol dm-3 and 0.001 mol dm-3) were controlled by different type of electrolytes (NaClO4, NaCl, KCl, CsCl). Absolute values of surface potential were calculated from electrode potentials using the electrokinetic isoelectric point, as the point of zero potential. The slope of phi0(pH) function, with respect to pH, was found to be lower than the Nernstian. This effect was more pronounced at higher ionic strength. The specific influence of different anions (Cl- and ClO4-), is observed below the point of zero potential, because positive surface promote association of anions. The association affinity of Cl- ions was found to be higher than for ClO4-. Measurements of surface potential enable evaluation of the ratio of surface concentrations of negative and positive sites. This is useful information because adsorption data provides only the differences of surface concentrations of negative and positive sites. These results, combined with surface charge density sigma0 (obtained by potentiometric acid-base titrations of metal oxide colloid suspensions) and with counterion adsorption data enable the determination of singular values of surface concentrations of negative and positive groups. This is essential for interpretation of calorimetric acid-base titration of metal oxide colloid suspensions where one should separate extent of protonation and deprotonation of neutrale surface sites. The calorimetric acid base titrations of TiO2 suspension were performed and the standard enthalpies of surface protonation and deprotonation, and electrostatic contribution to these quantities, were determined.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA