1976 Volume 49 Issue 1 Pages 15-21
Coprecipitation of aluminum compounds with iron (III) compounds by sodium hydroxide was investigated, for the purpose of studying the preparation of pigments of iron oxide-aluminum oxide system by coprecipitation method.
The results were summarized as follow :
Aluminum compounds began to precipitate at about pH 4.0 by adding sodium hydroxide to the solution containing only aluminum ion, and this aluminum compounds precipitate dissolved over pH 10.0. On the other hand, amount of precipitated aluminum compounds increased by adding sodium hydroxide to the solu ion containing iron (III) and aluminum ions, remarkably so at pH 11.0.
The mechanism of coprecipitation was much influenced by occlusion rather than by adsorption.
Iron (III) or aluminum compounds precipitation from corresponding pure salt solution in the range of pH between acidic to neutral was found to be the amorphous basic sulfate.
α-FeOOH was observed in such iron (III) precipitate at pH 12.0. However, α-Fe0OH was not recognized in coprecipitation products from (III) and aluminum solution at pH 12.0.