Adsorption properties and mechanism of mesoporous adsorbents prepared with fly ash for removal of Cu(II) in aqueous solution

Mesoporous materials were hydrothermally prepared from fly ash in an alkaline condition with cetyltrimethylammonium bromide as synthesis directing agent. The structural properties of the mesoporous materials were characterized by X-ray powder diffraction, high-resolution transmission electron microscope, and N2 adsorption. The chemical contents of SiO2 in the mesoporous materials were determined by spectrometry of the silicone molybdenum and sulfosalicylic acid complexes, and Al2O3 determined by complexometry with Ethylene Diamine Tetraacetic Acid in the presence of KF-Zn(Ac)2 tests. The removal of Cu(II) was studied under equilibrium and dynamic conditions, and the influence of the Al:Si molar ratio were also considered. The equilibrium data were fitted to Freundlich and Langmuir models and the models parameters were evaluated. The adsorption mechanism was clarified with the Dubnin–Radushkevich isotherm.