Photocatalytic Degradation of Aqueous Rhodamine 6G Using Supported TiO2 Catalysts. A Model for the Removal of Organic Contaminants From Aqueous Samples

Abstract

As a model for the removal of complex organic contaminants from industrial water effluents, the heterogeneous photocatalytic degradation of Rhodamin 6G was studied using TiO 2-derived catalysts, incorporated in water as suspension as well as supported in raschig rings. UV and Visible light were tested for the photo-degradation process. TiO 2 catalysts were synthesized following acid synthesis methodology and compared against commercial TiO 2 catalyst samples (Degussa P25 and Anatase). The bandgap (E g) of the TiO 2 catalysts was determined, were values of 2.97 and 2.98 eV were obtained for the material obtained using acid and basic conditions, respectively, and 3.02 eV for Degussa P25 and 3.18 eV for anatase commercial TiO 2 samples. Raschig ringssupported TiO 2 catalysts display a good photocatalytic performance when compared to equivalent amounts of TiO 2 in aqueous suspension, even though a large surface area of TiO 2 material is lost upon support. This is particularly evident by taking into account that the characteristics (XRD, RD, Eg) and observed photodegradative performance of the synthesized catalysts are in good agreement with the commercial TiO 2 samples, and that the RH6G photodegradation differences observed with the light sources considered are minimal in the presence of TiO 2 catalysts. The presence of additives induce changes in the kinetics and efficiency of the TiO 2-catalyzed photodegradation of Rh6G, particularly when white light is used in the process, pointing toward a complex phenomenon, however the stability of the supported photocatalytic systems is acceptable in the presence of the studied additives. In line with this, the magnitude of the chemical oxygen demand, indicates that, besides the different complex photophysical processes taking place, the endproducts of the considered photocatalytic systems appears to be similar.

Optimal H2O2 concentration in advanced oxidation over titanium dioxide photocatalyst

“…Titanium dioxide with crystalline anatase modification is well-known as a photocatalyst [1,2]. The advantages of titanium dioxide are the following: high photocatalytic activity, chemical and thermal stability, low cost and negligible toxicity [2,3].…”

High-Resolution Cryo-Electron Microscopy Reveals the Unique Striated Hollow Structure of Photocatalytic Macrocyclic Polydiacetylene Nanotubes

“…As the curcumin uptake experiments in Figure attest to the capability of the hollow MDA-1 nanotubes to efficiently adsorb small organic molecules, we further investigated whether the nanotubes facilitate scavenging and photocatalytic degradation of water pollutants (Figure and Figure S14). Figure a depicts the extent of light-induced degradation of R6G, a model pollutant dye, monitored by recording the R6G absorbance peak at 526 nm . Importantly, in the experiments shown in Figure , we compared the photocatalytic R6G degradation in solutions containing mature MDA-1 nanotubes (Figure c) and in aqueous suspensions hosting non-tubular MDA-1 aggregates (Figure b) (prepared through fast addition of preheated water to the MDA-1 monomers dissolved in acetone; the TEM micrographs in Figure underscore the morphological differences between the two species).…”

Photocatalytic Decomposition of an Azo Dye Using Transition-Metal-Doped Tungsten and Molybdenum Carbides

“…This leads to the formation of reactive oxygen species necessary for the oxidation and subsequent mineralization of the organic contaminants. 24 …”