Mechanistic Insights into Biodegradable Silica-Starch Composite Materials-Structural and Adsorption Properties

Silica-starch composites were synthesized via a modified sol-gel route and evaluated as low-cost, biodegradable adsorbents for the removal of organic dyes from aqueous solutions. The formation of mesoporous hybrid networks and structural reorganization of starch upon integration with the silica phase were confirmed. The physicochemical properties of the composites were examined using nitrogen adsorption-desorption analysis, SEM imaging, SAXS, and XRD, providing complementary insights into their porous structure, morphology, and structural organization. Adsorption performance and kinetics were evaluated through continuous UV-Vis spectroscopic monitoring of dye concentration during the sorption process. Adsorption studies using methylene blue demonstrated that dye uptake proceeds through a combination of electrostatic interactions, hydrogen bonding between dye molecules and hydroxyl-rich starch domains, and diffusion-driven retention within the mesoporous silica framework. The proposed materials offer significant advantages arising from their simple, inexpensive synthesis and fully biodegradable nature. These features position silica-starch composites as sustainable sorbents suitable for environmentally oriented water purification applications.