The orthogonal optimization of reactive mixture ratio of silica xerogels

Two-step acid-base catalyzed silica xerogels were prepared through sol-gel and ambient pressure drying. Various additive components were main factors which influenced the preparation of silica xerogels. The four-factor, three-level orthogonal test was designed to investigate the effect of the molar ratio of water, alcohol, hydrochloric acid and ammonia for obtaining silica xerogels of the minimal density and the maximal porosity. In order to ensure every experiment to generate under the same processing conditions, the other processing parameters were also confirmed. The result showed that the optimal mixture molar ratio of TEOS, H₂O, alcohol, hydrochloric acid and ammonia was 1 : 4 : 10 : 7.5 × 10^-4 : 0.0375.