Impact of synthesis conditions on meso- and macropore structures of resorcinol–formaldehyde xerogels

Xerogels were prepared by the sol–gel polymerization of resorcinol with formaldehyde at different conditions. The effects of different synthesis factors (namely, resorcinol-to-formaldehyde ratio, resorcinol-to-water ratio, resorcinol-to-catalyst ratio, and initial solution pH) on the surface areas, pore volumes, pore size distributions, and adsorption capacity of liquid nitrogen were studied. Factorial design was also used to investigate the relative significance of these factors on the resulting xerogels properties, and the possible interactions between them. The mean effects of the most significant factors and factor interactions on determining the pore structures and adsorption capacities were evaluated. The synthesized xerogels were characterized by Fourier transmission infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, and surface area analyzer. The results showed that surface areas, pore size distributions, and nitrogen adsorption capacity are dependent completely on the recipes used to prepare the xerogels. Pore structure results put xerogel samples as candidates for adsorption technology, ultra-filtration, and nano-filtration fields based on pore sizes and pore volume scales.