Silica-based microspheres with interconnected macroporosity by phase separation

Porous Silica Microspheres with Immobilized Titania Nanoparticles for In‐Flow Solar‐Driven Purification of Wastewater

“…Silica-based microscaffolds were synthesized according to a modified method previously reported, [14] developed by Marques et al This process follows the steps of any silane-based sol-gel reaction. However, condensation reactions are made to occur inside the water droplets of a templating water-in-oil (W/O) emulsion, to obtain particles with a spherical shape.…”

“…The synthesis process of the SiO 2 MSs employed in this work consists of a new approach based on W/O emulsification combined with an adapted sol-gel technique. It has been recently described elsewhere, [14] including the study of the reaction medium evolution during the synthesis of the MSs. Specific synthesis reaction parameters were selected, such as surfactant amount, emulsification speed, pre-hydrolysis time, and HCl/ silanes molar ratio, to achieve MSs with the desired particle size distribution and interconnected porosity.…”

“…After the heat treatment of the SiO 2 MSs at 900 °C, broad and strong absorption bands peaked at ≈1060, 800 and 450 cm −1 are found in the spectrum revealing the presence of a silica-based inorganic material, whose assignments are well explained in refs. [14,51] for instance. It should be stressed that the band at ≈1060 cm −1 exhibits a large full width at half maximum (FWHM) and is slightly shifted to lower frequencies.…”

“…This might be associated with the broadening of the bond angle distribution [51] previously reported to derive from the large porosity characteristic of these MSs. [14] Further evidence of porosity comes from the relatively strong shoulder of the peak at 1060 cm −1 , located around 1200 cm −1 , which has been associated with the presence of residual material porosity. [52] With the loading process, the main feature arising at the FTIR-ATR spectrum is the increased absorption in the range of 850-400 cm −1 , which derives from the presence of TiO 2 NPs.…”

“…A new class of support material, that is, a silica-based microscaffold of spherical shape (MSs) with custom-tailored porosity, has been recently developed by a novel method that combines emulsion templating with an adapted sol-gel technique. [14,15] Its interconnected macroporosity is due to phase separation by polymerization-induced spinodal decomposition, and a benefit of this method is that no specific gelation additives are needed to promote such phase separation.…”