Catalytic ozonation promoted by alumina-based catalysts for the removal of some pharmaceutical compounds from water

Catalytic ozonation of three selected pharmaceutical compounds (diclofenac, DCF, sulfamethoxazole, SMX, and 17α-ethynylstradiol, ETOL) in the presence of a commercial γ-Al2O3 and a synthesized Co3O4/Al2O3 catalyst has been studied. Experiments were carried out with the pharmaceuticals spiked in both, ultrapure water (Milli Q, Millipore) and an actual secondary effluent from a municipal wastewater treatment plant (MWWTP). Regardless of the water matrix and the presence or absence of any catalyst, the removal of the three pharmaceutical compounds developed through fast direct reactions with ozone (i.e., the compounds were totally removed in less than 10 min). In terms of COD and TOC removals, catalytic ozonation, especially in the presence of the Co3O4/Al2O3 catalyst, clearly enhanced the results obtained when the single ozonation process was applied. The stability and reusability of the Co3O4/Al2O3 catalyst was demonstrated by carrying repetitive experiments reusing a catalyst sample. Finally, a kinetic model that accounts for two reaction stages has been proposed and apparent rate constants have been computed.