Evaluation of the Influence of Microwaves in the Structure of Silica Gels

Abstract

In this work we studied the influence of microwaves in the pore structure of silica gels obtained via sol-gel polymerization process. We analised the feasibility of replacing conventional heating by microwave heating during drying. Structural parameters such as specific volume of pores (Vp), specific surface area (Sp), average pore size (r p) and the bulk and true densities were measured. X-ray diffraction confirmed the obtention of a completely amorphous structure for the gels. Some characteristics of silica gels were evaluated by thermogravimetric analyses (TGA), differential thermal analyses (DTA) and Fourier transform infrared spectroscopy (FTIR). We observed that microwave drying is a feasible process to yield controlled pore nanostructures. The gels obtained via microwave heating presented average pore size of 1.2 nm, specific surface area of 112 m²/g and specific volume of pores of 0.06 cm³/g. The gels obtained via conventional heating presented average pore size of 1.3 nm, specific surface area of 748 m²/g and specific volume of pores of 0.49 cm³/g.

Keywords

• structure
• sol-gel and microwave