Preparation and properties of the stable sols of aluminium hydroxide. Study of the process of peptization of highly-disperse aluminium hydroxide

Studied has been the process of peptization of highly-disperse aluminium hydroxide (pseudobemit) obtained by hydrolysis of secondary aluminium butoxide. The concentrations of pseudobemite and nitric acid have been determined, at which uniform sols and gels are formed. It has been established that in the sols and gels prepared by peptization of pseudobemit, there occurs slow dissolution of a disperse phase until the pH-value increases up to 3-4; in this case, the pH increase rate is constant, being the higher the lower the acid to pseudobemit relationship. The optical density of the sols that have been sufficiently long held at room temperature depends but slightly on their prehistory. The pseudobemit sols prepared by this method were used for manufacturing ultraporous membranes.