Iron silicate colloids preparation

The preparation of lyophilic sols is easy and most of the time a mixture of the dispersion medium and the substance to be dispersed need only be stirred. Gelatine, for example, disperses almost spontaneously in water. The hydroxides of iron, aluminium, chromium and zirconium as well as vanadium pentoxide and silicic acids all belong to the group of hydrophilic colloids. 

Four precipitated iron-based catalysts were used. The first catalyst consisted of only iron. The other catalysts contained either added potassium, added silicon or both. The catalysts were designated in terms of the atomic ratios as lOOFe, 100Fe/3.6Si, 100Fe/0.71K and 100Fe/3.6Si/0.71K. The catalysts were prepared by continuous precipitation from iron (111) nitrate and concentrated ammonium hydroxide. For silica-containing catalysts, a colloidal suspension of tetraethyl ortho silicate was mixed with the iron nitrate solution prior to precipitation. Potassium was added to the catalysts in the form of potassium tertiary butoxide during the loading of the FTS reactor. 

Some 26 pages later in that monumental paper, Graham addressed the preparation of colloid substances by dialysis , and on the topic of soluble silicic acid he describes the preparation of dilute silica sols and their properties, including stability, gelation, and syneresis. In this paper, which ironically is primarily directed to the study of liquid diffusion, we witness the birth of colloidal chemistry. 

This example describes the preparation of sand cores bonded with colloidal silica powder, sodium silicate and polyvinyl acetate ethylene copolymer and their use in the production of cast iron end plates for boilers. 

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