Simultaneous Hydrogen Production and Acetic Acid Degradation by Heterogeneous Photocatalysis using a Metallurgical Waste as Catalyst

This study presents the generation of a renewable fuel using acetic acid as electron donor, copper slag (CS) as photocatalyst and UV–Vis irradiation. The CS was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and UV–Vis spectroscopy. Specific surface area (SBET) was determined on basis of N2 isotherms. A 23 factorial experimental design was performed to identify factors controlling the hydrogen evolution and mineralisation of acetic acid. The experimental factors were: slag dose (0.1, 0.55 and 1 g/L), acetic acid concentration (1, 5.5 and 10% vol) and reaction time (2, 5 and 8 h). Synthetic acetic acid solutions were used. An Analysis of Variance (ANOVA) was performed showing that slag dose, reaction time and an interaction between both factors were statistically significant (p-value < 0.05) for hydrogen generation. Two absorption edges (2.2 and 2.6 eV) were determined associated with the presence of fayalite and magnesioferrite identified by XRD. The best rate of the hydrogen production was 4.35 μmol/h g CS at 10% vol acetic acid, 0.1 g/L of CS and 2 h of reaction. This value is similar to values reported using similar catalysts. CS performance is due to the high iron content (60.09% wt. as Fe2O3) and traces of other semiconductors such as zinc, copper and manganese which may have some contribution to the photocatalytic activity.