Microstructure of aluminum hydroxides and the formation of aluminum dye lakes.

The effect of processing variables on the type of aluminum hydroxide and the dye content of the resultant lakes were investigated. The solid-state structure of aluminum lakes in conjunction with the associated aluminum hydroxide was studied by electron microscopy, X-ray diffraction, and IR spectroscopy. The conditions under which the aluminum hydroxide was prepared were shown to govern the amorphous/crystalline character of the product, which was reflected in changes in particle size and surface area. A hypothesis for the interaction of the dye and aluminum hydroxide is formulated in which the amount of dye adsorbed on the aluminum hydroxide is dependent on the surface area of the microstructures present.