Formation of spherical microporous silica particles from organosilane and quat molecules

The approach is developed to obtain submicron spherical particles of amorphous silica with interconnected micropores. The particles were synthesized via hydrolysis of organosilanes, i.e. tetraethoxysilane (TEOS) and (3-methacryloyloxy) propyltrimethoxysilane (MPTMOS) in a presence of quat surfactants. It was shown that the replacement of a part of TEOS with MPTMOS in the reaction mixture led to formation of particles containing only micropores instead of mesopores. At comparable amounts of MPTMOS and quat for both C-quat > CMC and C-quat < CMC the particle growth mechanism changed from aggregative to that of the layer-by-layer type. Presumably, various associates are formed in the reaction mixture from quat surfactant and MPTMOS molecules by the van der Waals and Coulomb interactions. The associates are built into the silica framework formed as a result of hydrolysis of organosilanes. After the organics are removed, a branched system of interconnected micropores 0.5 - 2 nm in size is formed within the particles at place of the associates. The synthesized microporous particles have a specific surface area of up to similar to 1000 m(2) g(-1) and pore volume of up to 0.5 cm(3) g(-1). The adsorption of transition-metal ions (Co2+, Ni2+) by the synthesized microporous particles was studied. It was shown that the adsorption capacity of microporous particles is twice that of particles with mesopores.

Automated summary

The approach developed in this study aims to obtain submicron spherical particles of amorphous silica with interconnected micropores. By replacing a part of tetraethoxysilane (TEOS) with (3-methacryloyloxy) propyltrimethoxysilane (MPTMOS) in the reaction mixture, the particle growth mechanism changes and particles containing only micropores are formed. The synthesized microporous particles show higher adsorption capacity for transition-metal ions compared to particles with mesopores.