Quantitative Study of the Enhanced Content and Chemical Stability of Functional Groups in Mesoporous Silica by In-Situ Co-Condensation Synthesis

The chemical stability and content of organic functional groups significantly affect the application of materials in the field of adsorption. In this study, we quantitatively studied the effect of in-situ co-condensation and post grafting on the physico-chemical properties and sorption properties of modified mesoporous silica. The results showed that the grafting method changed the morphology of mesoporous silica while the in-situ method kept the spherical morphology well, and the amino groups were both successfully introduced into the materials. Besides, the amino content of the material prepared by in-situ method (ami-MSN) was 2.71 mmol/g, which was significantly higher than the 0.98 mmol/g of the grafting method (ami-g-MS). Moreover, the chemical stability of functional groups in ami-MSN was much better than ami-g-MS. Furthermore, ami-MSN showed better capability in removing toxic metals of Pb, Cd, Ni, and Cu, and the removal efficiency of Pb reached 98.80%. Besides, ami-MSN exhibited higher dynamic CO2 adsorption of 0.78 mmol/g than ami-g-MS of 0.34 mmol/g. This study revealed the relationship between modification methods and the modification efficiency, functional groups stability, and sorption properties through quantitative comparative studies, which provided a reference for preparing modified mesoporous silica materials with high sorption properties.