Gel time

polymerization rate of monosilicic acid

and thermal performance of gel of silicic acid system with coexisting Mg2+ and Al3+ ions were investigated. At pH<4

gel time of silicic acid system decreased with the increase of coexisting concentration of Mg2+ and Al3+ ions

and Al3+ ions played an important role in the coagulation process. Polymerization reaction rate constant of monosilicic acid

for silicic acid system with coexisting Mg2+ and Al3+ ions

was higher than that for silicic acid without metallic ions

and average rate constant for MA0.1+0.1 system was k0=7.28×10-4

k1=5.62×10-4. Crystallization temperature and crystal transformation temperature of silicic acid system with coexisting Mg2+ and Al3+ ions were lower than those of silicic acid without metallic ions

and chemical formula of hydrated silicon dioxide for MA0.1+0.1 system calculated by TG curve was SiO2·0.556 H2O.