Aqueous silica-titania interaction

Iler DS coatings have been a major success in the pigment world, and the Iler process may well be of value in the world of useful photocatalysis. Studies of silica adsorption on titania, via uptake and electrophoresis measurements and gas adsorption characterization procedures, have enabled an explanation of the nature of specific interactions between aqueous silica and titania. Binding is proposed to occur preferentially via hydrated cation sites on titania, and the occurrence of such binding is concluded to provide the basis for the subsequent surface polymerization necessary for the buildup of coherent multilayer silica. 

The SPSDs of mixed oxides (initial and carbonized) depend strongly on pH (Figures 2.53, 2.55, and 2.56) since the electrostatic interactions between silica, titania, alumina, andpyrocarbon phases characterized by different points of zero charge, PZC are differently affected by pH (Figures 2.52 and 2.54). The studied characteristics of nanooxides can correlate with the adsorption of metal ions because of the common basis (structure of oxide particle surfaces and their behavior in the aqueous medium) of these phenomena. 

Although endcapped columns offer some advantages, the aqueous instability is still problem. To over come these problems of silica based columns, alternative supports like alumina (AI2O3), zirconica (Zr02), and titania (Ti02) have been developed. Alumina columns are stable in the pH range of 2-12, while zirconia columns extend the range from 0 to 14. These are basic oxides and hence silanol-like interactions are... 

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