engleski

Effects of Polyion adsorption on aggregation of TiO2 particles

Mineral/aqueous electrolyte interfaces play an important role in numerous environmental and technological processes. Surface modification by binding polyions is of particular importance in the above mentioned systems since the formation of mono- or multilayers affects the surface reactions and mineral surface properties significantly. Polyelectrolyte coatings can lead to particle aggregation or, if introduced in excess with respect to charged surface groups, their stabilization. The modified polyelectrolyte-coated mineral surfaces can exhibit some quite different properties from the minerals themselves [1, 2]. In this study, the surface properties of TiO2 particles before and after the adsorption of polyelectrolytes were investigated. As polyions, strongly charged poly(N-ethyl-4-vinylpyridinium) cations (PVP4) and poly(diallyldimethylammonium) (PDADMA), weakly charged poly(allylammonium) cation (PAH) and weakly charged poly(acrylate) anion (PA) were used. The surface of TiO2 particles was characterized by means of dynamic and static light scattering (DLS and SLS) and measurements of inner surface potential as well as electrokinetic potential. Inner surface potential was measured by means of TiO2 single crystal electrode (CrE) [3]. Different experimental methods are used in order to simultaneously measure different parameters related to surface reactions on the selected polyelectrolyte-coated minerals. Based on the obtained parameters and measured surface potentials, a more detailed picture of the electrical interfacial layer, ion distributions and mechanisms of the processes at the mineral / electrolyte solution interface can be deduced.

adsorption, polyelectrolites, titania, surface reaction, surface potential, aggregation

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