PREPARATION AND PROPERTIES OF STABLE SOLS OF ALUMINUM HYDROXIDE - STUDY OF PROCESS OF PEPTIZATION OF HIGH-DISPERSITY ALUMINUM HYDROXIDE

A study has been made of the process of peptization of high-dispersity aluminum hydroxide (pseudoboehmite) obtained by hyrolysis of aluminum sec-butoxide. Concentrations of pseudoboehmite and nitric acid for th e formation of uniform sols or gels have been determined. It has been established that in pseudoboehmite sols and gels obtained as a result of peptization, the disperse phase dissolves slowly until the pH rises to the 3-4 level; here the rate of increase of pH is constant and is higher for lower ratios of acid to pseudoboehmite. The optical density of a sol that has been held for a rather long period at room temperat ure depends on the prehistory of the sol. Pseudoboehmite sols obtained by this method have been used in the preparation of ultraporous membr anes.