Fabrication of mesoporous Al-SBA-15 as a methylene blue capturer via a spontaneous infiltration route

Abstract

Different amounts of aluminum (Al) species were infiltrated and incorporated into SBA-15 by grinding the mixture of aluminum nitrate and SBA-15 followed with a subsequent calcination. A novel series of methylene blue adsorbents were thus obtained and characterized by X-ray diffraction, N₂ adsorption–desorption, Fourier transform infrared and ²⁷Al Nuclear Magnetic Resonance (NMR) techniques. Results show that the newly synthesized Al-SBA-15 materials have well-preserved mesostructures, high BET surface areas, enlarged pore sizes and predominantly tetrahedrally coordinated Al species. All Al-SBA-15 materials show a greater adsorption capacity to methylene blue than SBA-15, where the sample (Al/Si = 0.05) has the largest capacity to remove MB from water solution. Diffuse reflectance measurements, Langmuir and Freundlich equations and the pseudo-second-order kinetic model were further used to describe the adsorption behavior of MB onto SBA-15 and Al-SBA-15 materials. Finally, recycling tests were performed to evaluate the stability of the Al-SBA-15 material and the textural and NMR properties of the used samples were also detected.