Effect of dilution on reactivity and structure of aluminum hydroxide gel

Aluminum hydroxide gel loses reactivity upon aging. However, a sharp decrease in reactivity occurs when the gel is diluted with double-distilled water. The loss of reactivity is directly related to the degree of dilution, but dilution with dioxane or the mother liquor has no effect on reactivity. It is hypothesized that dilution with water causes a change in the equilibrium between stabilizing ions incorporated in the gel structure and ions in solution. As the stabilizing ions leave the gel structure to reestablish the equilibrium, a loss of reactivity is observed until a new equilibrium is established.