Synthesis of magnetized SBA-15 using one-pot synthesis method: removal of methylene blue dye from water effluent

Abstract

Fe-SBA-15 was synthesized as an highly functional magnetic adsorbent by forming magnetic Fe3O4 nanoparticles in the mesoporous silica matrix using the direct synthesis method. The purpose of this study was not only to determine the possible interactions between adsorbate (MB) dye molecules and adsorbent but also to elucidate the potential of this material for the removal of MB from wastewater. X-ray Diffractograms (XRD) of SBA-15 and Fe-SBA-15 both show similar characteristic peaks, suggesting that the crystallinity of the material was not affected even after the incorporation of the iron oxide. Surface electron microscopic (SEM) imaging of SBA-15, Fe-SBA-15 and MB-Fe-SBA-15 showed distinct changes in pore morphology. The size of Fe-SBA-15 shows the decreased on the microscopic scale indicates the successful incorporation of iron oxide onto SBA-15. In the adsorbent performance test, it was found that the MB could be adsorbed completely in 24 hours and the magnetic adsorbent could be separated easily from water by applying the magnetic separation technique using a magnet bar. The isotherms of the adsorption process were discussed in detail by data fitting of the Langmuir, Freundlich and Temkin isotherms while the kinetics study was examined by pseudo first-order, pseudo second-order and intra-particle diffusion models. For adsorption isotherm, the model follow Temkin isotherm model since the value of R2 (0.9933) is nearer to 1 indicating the applicability of thisisotherm. The adsorption kinetics follow the pseudo-second order kinetics model since the value of R2 is 0.987 which is nearer to 1 higher indicating chemical adsorptioninvolving valences force by exchange or sharing of electrons between the Fe-SBA-15 and MB dye. These findings suggested that the MB molecules are actually chemically adsorbed onto the synthesized magnetic SBA-15.