Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 40485
Title Electro-kinetic measurements on plugs of doped titania.
Author(s) Spanos, N.; Tsevis, A.; Koutsoukos, P.G.; Minor, M.; Linde, A.J. van der; Lyklema, J.
Source Colloids and Surfaces. A: Physicochemical and Engineering Aspects 141 (1998). - ISSN 0927-7757 - p. 101 - 109.
Department(s) Physical Chemistry and Colloid Science
Publication type Refereed Article in a scientific journal
Publication year 1998
Abstract The z-potential and the surface conductivity of pure anatase and anatase doped with Li , Nb5 and W6 prepared with both the precipitation (continuous crystallization at constant supersaturation) and the sol-gel method have been determined at two pH values (3.3. and 6.0 or 6.5). This was carried out by measuring the streaming potential and electrical conductivity of a porous plug containing the anatase particles. The sol-gel preparations exhibited a higher density than those obtained by precipitation. Plots of the plug conductivity as a function of the conductivity of the solution are essentially linear, allowing for the establishment of the surface conductivity, K. The main contribution to K stemmed from the counter charge behind the slip plane. At pH 3.3, i.e. much lower than the i.e.p., doping with Nb5 and Li caused a considerable increase of the surface conductivity in both preparations, whereas at a pH 6.0 or 6.5, i.e. near the i.e.p., doping led to a slight decrease of the relatively high surface conductivity of the sample prepared by precipitation. At pH 6.5 sol-gel preparations showed negligible surface conductivity, independent of the doping, with the exception of the preparation with a high concentration of W6 . Moreover, doping with W6 did not considerably change the surface conductivity. There is some indirect correlation between the surface and the bulk conductivity of the various samples. Tangential mobilities of Cl- ions in the stagnant layers are of the same order of magnitude as those in the bulk solution.
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