Solid-fluid interactions.Phase I.Study of superficial properties of some metallic oxides

Solid -fluid interactions phenomena play a major role in various process like adhesion, adsorption, catalysis, charge properties, etc...Two types of interactions can be distinguished: solid-liquid interactions and solid-gas interactions. we were interested, in this paper, in the superficial characterization of some solids dispersed in organic or aqueous media by measuring their zeta potential. We proposed a new method to calculate the donor and acceptor numbers of a solid. Inverse gas chromatography technique was used to determine the specific interactions between metallic oxides (ZnO, Zn (OH)2, MgO, etc.) and model organic molecules. We proved the amphoteric feature of such oxides by calculating their acidic and basic parameters. It was proved that MgO is more basic than the other oxides and ZnO is rather acidic. We proposed a new method to calculate acidic KA and basic KD parameters of a solid by adding a third parameter K in the relationship that related specific enthalpy variation (-ΔHsp) of polar molecules to their acceptor number AN and their donor number DN. The parameter K (-ΔHsp)=KA.ND+KD.NA-K.NA.ND We proved that our model gives the best results relatively to those obtained by the classic equation. (Author)