TiO2 and modified TiO2/Fe on photocatalytic reduction of Hg2+ using artificial and solar radiation

Mercury is a highly hazardous water contaminant; both organic and inorganic forms are cumulatively and extremely toxic. In this context, this study describes the application of TiO2-based systems modified with 5, 8, 10 and 15 wt% Fe using the impregnation method for the photocatalytic reduction of Hg2+. Characterization of TiO2 and synthesized materials was performed by using Brunauer, Emmett and Taller area, pore diameter and pore volume, scanning electron microscopy, point zero charge, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, photoacoustic and Mössbauer spectroscopy. The photocatalytic reduction of Hg2+ was performed in batch stirred tank reactor and compound parabolic collector solar photoreactor, in the presence of catalysts, under four different reaction conditions. The process of heterogeneous photocatalysis was studied in the treatment of synthetic wastewater containing mercury chloride (HgCl2) in different reaction conditions. In particular, the influence of oxygen and formic acid was analyzed. The results showed that an addition of 8% to the iron weight improved the performance of the photocatalytic titania in the reduction of Hg2+ (artificial radiation). In the presence of this catalyst, and reaction medium containing only mercuric chloride in an aqueous solution containing oxygen, Hg2+ was 100% reduced, after 3 h of reaction. However, under solar radiation, the reduction of Hg2+ obtained was 67%.