Photocatalytic ozonation of monuron over suspended and immobilized TiO2-study of transformation, mineralization and economic feasibility

The transformation and mineralization of monuron herbicide were investigated by heterogeneous photocatalysis, ozonation, and their combination (photocatalytic ozonation) at various ozone (O-3) concentrations (0-20 mg dm(-3) in gas phase), using TiO2 in suspensions and in immobilized form. The applied AOPs were characterized by the transformation and mineralization rate of monuron, the concentration of dissolved O-3, and the economic feasibility based on the values of Electrical Energy per Order related to the rate of decrease of monuron concentration and of the total organic carbon content. In the case of photocatalytic ozonation, the transformation and mineralization rate of monuron increased with the increase of O-3 concentration. However, there was no significant synergistic effect. Electrical Energy per Order decreased with the increase of O-3 concentration, and economical efficiency of the photocatalytic ozonation using TiO2 in suspensions highly exceed that of both ozonation and heterogeneous photocatalysis regarding the value determined for the decrease of total organic carbon content. (C) 2018 Elsevier B.V. All rights reserved.