Synthesis of Octa(maleimidophenyl) silsesquioxane–SiO₂/TiO₂ Hybrid Nanocomposites: Adsorption Behavior for the Removal of an Organic Methylene Blue Dye and Antimicrobial Activity against Pathogens

In this study, a sol–gel process was used to prepare hybrid nanocomposite consisting of octa(maleimidophenyl) silsesquioxane-silica/titania (maleimide–POSS (polyhedral oligomeric silsesquioxanes)–SiO₂/TiO₂) to use in methylene blue (MB) adsorption and as an antibacterial agent. The structure, surface, and morphological characteristics were confirmed through Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The optical and thermal stabilities were studied by conducting UV–visible and thermogravimetric analysis–differential scanning electron calorimetry analysis. The experimental results showed a maximum dye adsorption capacity of 92% achieved using 0.5 g of hybrid nanocomposite after 2.5 h at pH 9. We also investigated the effect that the adsorbent dosage, pH, and contact time had on the removal efficiency of the MB dye in aqueous solution. The recycling experiment showed a good adsorption capacity of the MB dye, even after five repeated cycles. Furthermore, the hybrid nanocomposite was tested against pathogenic bacteria, such as Bacillus cereus, Lactobacillus, Escherichia coli, and Pseudomonas aeruginosa. The nanocomposite was observed to be highly sensitive to E. coli, B. cereus, and P. aeruginosa, as confirmed by the size of the zone inhibition.