Synthesis Of High Purity Silica Substrate As Chromatographic Column Packing Materials

As a high efficient separation and analysis method, Chromatography plays a more and more important role in today's production, scientific research, monitoring and testing fields. More and more efforts have been devoted to the synthesis of mesoporous silica spheres of defined size and pore diameter because the control of the particle morphology and pore size of mesoporous silica makes it the most commonly used as a packing material in chromatography. Micrometer-sized mesoporous silica spheres can be used as chromatography stationary phases, in which crucial parameters are dispersion, purity, high surface area, well-defined pore size and uniform particle size. Here, we reported the production of monodisperse small silica particles of controllable sizes by a straightforward scalable method using one of the most affordable silica precursors—elemental silicon, which are including three main processes. First, controlled hydrolysis under the catalysis of ammonia is employed in the fabrication of silica nanoparticles having a highly monodispersity. The purity of the colloidal suspensions obtained is analyzed by ICP-MS. Second, the prepared monodisperse urea resin/SiO2 polymer composite microspheres by polymerization-induced colloid aggregation (PICA) is used to produce spherical silica. The obtained mesoporous silica spheres are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET. Finally, homogenate filling method is adopted to pack the mesoporous silica spheres into a column and the separation performance of the mesoporous spheres materials has also been determined.It is concluded that the samples obtained at 80℃for 6h exhibit a perfectly spherical morphology with average particle size ranging at about 25nm; For the second step, when we set the mass ratio of urea resin/SiO2 at 1:3, the mole ratio of urea/methanol at 1:1.5, pH=1～2 and response time at 12h, we can get uniform particle size distribution,better dispersancy and smooth surface density spherical silica gel; And for the last step, through testing, microspheres show high mechanical strength and completely meet the requirements of chromatographic analysis.