Effect of silicic acid concentration on green mesoporous silica synthesis

Abstract

Tetraethoxysilane is the most commonly used precursor for obtaining mesoporous silica, it is economically expensive, so the use of inexpensive precursors such as sodium silicate or silicic acid are of interest for the economic production of said materials; silicic acid is generally obtained from sodium silicate by adjusting the pH of the system to 3-4 or through the use of ion exchange resins, this second methodology allows to eliminate the use of acid or basic catalysts in the synthesis of materials, which potentiates these materials for bioparticle encapsulation applications. The effect of the poly-condensation of silicic acid in obtaining mesoporous silica has been little evaluated, so this work shows the study of the effect of the degree of polycondensation of silicic acid on the textural properties of the materials, observing that at 0 and After 48 h of Si(OH)4 aging, the synthesized materials show a bimodal distribution of their pores at 4 and 8 nm, observing the majority presence of pores at 4 nm at 6, 24 and 72 h of aging.