Preparation, Characterization, and Use of Trimethoxy[3-(Methylamino)Propyl]Silane Functionalized Sba-15 for Congo Red Adsorption

Abstract

Mesoporous materials have aAbroad range of applications in industry, and one of which is their potential use in adsorptive separations. This research investigates the use of a secondary aminefunctionalized SBA-15 for the separation of a diazo dye, Congo Red (CR), from aqueous solutions. The synthesized SBA-15 was modified with trimethoxy[3-(methylamino)propyl] silane by a post-grafting method. The produced material was characterized using X-ray diffraction, N2 physisorption, scanning electron microscopy, and transmission electron microscopy. The hexagonal mesostructure was preserved after functionalization; however, the specific surface area, pore diameter, and total pore volume of SBA- 15 silica decreased. The adsorption of the diazo dye reached equilibrium by 50 minutes, and the data followed pseudo-second-order kinetics. While the yield increased with rising dosage and temperature, it decreased with CR concentration. The maximum adsorption capacity of functionalized SBA-15 (F-SBA-15) for CR uptake was found to be 211.07 mg/g. Thermodynamic data and parameters indicated the potential combination of physical and chemical interactions occurring during the adsorption process. The separation was endothermic and non-spontaneous; the equilibrium data fitted to the Freundlich adsorption isotherm at all tested temperatures. This study demonstrates that the secondary amine-functionalized SBA- 15 can be used for the elimination of a toxic anionic diazo dye from aqueous solutions.