Evaluation of metallurgical slag as a Fenton-type photocatalyst for the degradation of an emerging pollutant: Diclofenac

The aim of this study was to evaluate two metallurgical wastes (one from the copper (C-OB) and other from the steel (M-IT) industries) as Fenton-type photocatalysts for the degradation of diclofenac. C-OB exhibited higher photocatalytic activity since the radical (OH)-O-center dot radical production was greater with respect to the measured value of M-IT. This result is due to the better energy gap value compared with the value for M-IT (2.20 and 2.95 eV for C-OB and M-IT, respectively). The photodegradation process of diclofenac as a function of time by the C-OB/H2O2/simulated sunlight system can be described by a pseudo-first-order kinetics (k(app) = 0.046 min(-1)). The complete removal of diclofenac was achieved at 90 min using the Fenton-like system. At this reaction time, the system reached a total mineralization efficiency of 57.23%, and the effluent toxicity increased by 65% due to the possible generation of by-products that are more toxic than the parent compound. However, after 300 min of reaction time, the mineralization increased to 87%, and the initial toxicity was reduced by 70%. These results suggest that C-OB and M-IT possess suitable characteristics for their use as Fenton-type photocatalysts with potential applications in advanced oxidation processes (AOP) sunlight-assisted at near-neutral pH. (C) 2015 Elsevier B.V. All rights reserved.