Enhanced mineralization of pharmaceuticals by surface oxidation over mesoporous γ-Ti-Al2O3 suspension with ozone

Titanium-doped mesoporous gamma-Al2O3 (gamma-Ti-Al2O3) was prepared by an evaporation-induced self assembly method and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption, scanning electron microscope, and FTIR spectra of chemisorbed pyridine. gamma-Ti-Al2O3 revealed excellent catalytic ozonation activity and stability for mineralization of six drugs in aqueous solution, including ibuprofen, sulfamethoxazole, phenytoin, diphenhydramine, diclofenac sodium and acyclovir. The characterization studies showed that titanium was incorporated into the framework of gamma-Al2O3 by Al-O-Ti linkage, locating at tetrahedrally coordinated sites, which increased the Lewis acid sites of gamma-Al2O3, especially the medium acid sites. The surface atomic oxygen (equivalent to Al-3-*O) and peroxide species (equivalent to Ti4+-*O-2) were commonly generated rather than hydroxyl radical from catalytic decomposition of ozone in gamma-Ti-Al2O3 suspension on the basis of the electron paramagnetic resonance (EPR) and in situ Raman measurements. Furthermore, it was verified that the high mineralization of the tested pharmaceuticals came from the surface oxidization of organic acid intermediates by the common role of the surface atomic oxygen and peroxide species. (C) 2016 Elsevier B.V. All rights reserved.