Influence of process parameters on the morphological evolution and fractal dimension of sol–gel colloidal silica particles

Colloidal silica particles were synthesized from tetraethoxysilane (TEOS), ammonium hydroxide (NH4OH), ethanol (C2H5OH) and deionized water. Obtaining different structures was possible due to the variation of molar ratios of NH4OH, C2H5OH and H2O with respect to the precursor. The nature of the particles was evaluated using X-ray diffraction, energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The morphology of the particles was described using electron microscopy (SEM). Pore structure was characterized by nitrogen gas sorption-desorption, showing colloidal silica particles with solid-pores surface areas varying from 0.48 m2 g−1 up to 567 m2 g−1; pore volume varying from 0.0013 up to 0.88 cm3 g−1 and average pore radii varying between 1.4 and 36 nm. The fractal dimension of the silica particles and agglomerates varied from 2.0 to 2.12.