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

Abstract

a b s t r a c tMercury 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 TiO 2 -based systems modified with 5, 8, 10 and 15 wt% Fe using the impregnation method for the photocatalytic reduction of Hg 2+. Characterization of TiO 2 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 Hg 2+ 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 (HgCl 2 ) 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 Hg 2+ (artificial radiation). In the presence of this catalyst, and reaction medium containing only mercuric chloride in an aqueous solution containing oxygen, Hg 2+ was 100% reduced, after 3 h of reaction. However, under solar radiation, the reduction of Hg 2+ obtained was 67%.

Degradation of Caffeine by Heterogeneous Photocatalysis Using ZnO with Fe and Ag

“…The methodology proceeded with the following steps: the oxide used (ZnO) and the aqueous solution containing the metal precursor (AgNO3 or Fe (NO3).9H2O) were mixed and kept under constant stirring for 24 hours at room temperature. The metal solution was made so that the Fe or Ag nominal load was of 8% of the ZnO total weight by previously described in the literature [29]. After obtaining the mixture, the excess solvent (water) was removed by vacuum evaporation in the rotavaporation system with heating, at 90 °C and then the catalyst was dried at 100 ºC for 20 hours.…”