Catalytic Ozonation of Selected Pharmaceuticals over Mesoporous Alumina-Supported Manganese Oxide

Abstract

Catalytic ozonation of five pharmaceutical compounds (PhACs)phenazone, ibuprofen, diphenhydramine, phenytoin, and diclofenac sodium in alumina-supported manganese oxide (MnO_<i>x</i>) suspension was carried out with a semicontinuous laboratory reactor. MnO_<i>x</i> supported by mesoporous alumina (MnO_<i>x</i>/MA) was highly effective in mineralizing the PhACs in aqueous solution. Fourier transform infrared (FTIR) spectroscopy and in situ attenuated total reflection FTIR (ATR-FTIR) spectroscopy were used to examine the interaction of ozone with different catalysts under various conditions. The crucial active sites, surface oxide species at 1380 cm⁻¹, were formed by the interaction of ozone with Lewis acid sites on the alumina surface. New surface hydroxyl groups at 2915 and 2845 cm⁻¹ were produced by the interaction of the catalyst and ozone in aqueous suspension and became active sites in the presence of MnO_<i>x</i>. The introduction of MnO_<i>x</i> enhanced the formation and activation of surface hydroxyl groups, causing higher catalytic reactivity. On the basis of these findings, a reaction mechanism is proposed for the catalytic ozonation of PhACs in MnO_<i>x</i>/MA suspension.