Synthesis of Methylated Silica from Mineral Silicate Raw Materials

This paper presents research on the methylation of silicon dioxide surfaces derived from sulfuric acid decomposition of nepheline concentrate. Two methylation approaches were investigated: (1) direct attachment of methyl groups to the silica surface in nonpolar media with water molecule condensation, and (2) intermediate formation in an alkaline medium. Through comprehensive physicochemical characterization, we analyzed the morphology, surface elemental composition, and structural-surface properties of the methylated silica samples. The study revealed that silica subjected to direct methanol treatment exhibits a higher specific surface area (496 m2/g) compared to the sample prepared via alkaline intermediate formation (278 m2/g), likely due to the more complex synthesis mechanism of the latter. IR spectroscopy confirmed the presence of characteristic –C–H and –C–C-bond vibrations, indicating successful surface methylation. These findings, supported by porometry data, demonstrate partial hydrophobization of the silica surface and enhanced affinity for nonpolar organic compounds. The results suggest potential applications in developing membrane filters for organic compound separation.