Modelling and optimisation of sodium silicate based silica aerogel synthesis using response surface methodology

Abstract

The purpose of this work was to model and optimise the preparation of silica aerogel using low-cost material and modified sol-gel process. A central composite design was employed to optimise the synthesis factors. Among all factors discussed in literatures, silica concentration, gelation time and hydrophobic agent amount were the most efficacious ones. All experiments were performed at the same conditions, but the elected factors were varied in five levels. The response (density of silica aerogel) was fitted by quadratic regression model to find the optimal condition. Computation results showed that the minimum density of silica aerogel was achieved at silica concentration of 4.12 g/l, acid amount of 14.46 ml and trimethylchlorosilane (TMCS) consumption of 10.39 ml. The best density of silica aerogel was 0.078915 g/cm3 and the specific surface area determined by Brunauer-Emmett-Teller (BET) analysis was 780 m2/g.