Mesoporous silica MCM-41, SBA-15 and derived bridged polysilsesquioxane SBA-PMDA for the selective removal of textile reactive dyes from wastewater

Abstract

Treatment methodologies and precautionary measures are the topmost priority for sustainable development. Mesoporous silicates MCM-41, SBA-15 and its hybrid SBA-PMDA were directly employed to remove the textile reactive dyes from water at room temperature and neutral pH. These nanostructured materials were prepared and characterized by using FTIR spectroscopy, Nitrogen adsorption/desorption, NMR spectroscopy, X-rays diffraction, Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and Zeta potential. The cationic reactive dye brilliant green (BG) removal capacity of silicas SBA-15 and MCM-41 was found 119.0 mg g−1 133.20 mg g−1, respectively and zero affinity was observed for anionic dye reactive blue (RB 15) by these materials. In comparison, modified silica with PMDA bridged polysilsesquioxane SBA-PMDA, showed 25.66 mg g−1 of removal capacity for anionic dye RB 15. Kinetic studies showed that about 70% of the dye was removed within 4–5 h. To predict the system efficiency, the experimental data was treated with mathematical models such as Langmuir, Freundlich, Sips and Dubinin–Radushkevich isotherms, pseudo-first-order and pseudo-second-order. The obtained results suggest that nanostructured silicates could be simple, efficient, inexpensive and convenient adsorbents for the direct and selective removal of reactive dyes from water at room temperature.