Study of the particle size of silica sol catalyzed by acid

Silica sols have been prepared by acid-catalyzed hydrolysis and condensation reactions of tetraethylorthosilicate (TEOS). The FTIR spectrum of silica sol, the influences of reactant proportion and reaction temperature on the silica sol sizes, and the stability of the silica sol during aging process were investigated. The results show that the condensation reactions take place before the complete hydrolysis of TEOS, and TEOS hydrolysis is incomplete. The HNO(3)/TEOS molar ratio has less influence on the sol size while H(2)O/TEOS molar ratio has greater influence. As the molar ratios of HNO(3)/TEOS and H(2)O/TEOS,and the reaction temperature increase, the prepared sol sizes increase step by step. The sole sizes decrease with the increase of EtOH/TEOS molar ratio. During the aging process, the particle size and density of silica sol have unconspicuous change and the sol is relatively stable before the viscosity of silica sol sharply-increases. Low aging temperature can prolong the stable time of the silica Sol.