Effect of Anions on the Photocatalytic Activity of Fe(III) Salts Impregnated TiO₂

Abstract

This present work focuses on the photocatalytic activity of Fe(III) salt-impregnated TiO 2 catalysts for studying the effect of anion on the photocatalytic activity of the salt-impregnated catalysts. The salt-impregnated TiO 2 photocatalyst samples prepared using FeCl 3 , Fe(NO 3 ) 3 , and Fe 2 (SO 4 ) 3 were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectrophotometry (DRS), Fourier transform infrared absorption spectrophotometry (FT-IR), and surface area measurement by N 2 adsorption. Fe(III) ion impregnation of TiO 2 with different salts is observed to influence photocatalytic degradation of acetophenone. Fe(III) salt anions were observed to influence the initial rate of degradation. For example, the initial rate of degradation of acetophenone decreases with an increase in percentage of Fe(III) ions in the case of the catalysts prepared using ferric nitrate and ferric chloride salts. However, the initial rate of degradation was observed to increase with ferric sulfate impregnated catalysts. The final percentage degradation of acetophenone was found to increase continuously with an increase in Fe(III) ion concentration, irrespective of the anion. These observations have been discussed in terms of influence of the presence of Fe(III) ions on the recombination of the electron and holes generated during UV irradiation of TiO 2 . Similarly, the effect of anion has been discussed in terms of radical-scavenging ability of chloride and radical-generating ability of sulfate anions.

A surface science perspective on TiO2 photocatalysis

“…The presence of cationic species (e.g., Mg 2+ , Li + , Na + and K + ) at the surface of TiO 2 stabilized I − at or near the surface, enhancing its rate of oxidation (by a photoionized dye) in DSSC applications [1463]. In other cases, adsorbed surface cations enhanced charge recombination [1464].…”

Effect of surface Fe2O3 clusters on the photocatalytic activity of TiO2 for phenol degradation in water

“…For example, it is aqueous suspension of TiO 2 can greatly accelerate organic degradation under UV light [4][5][6]. Through a detailed study, Fe(OH) 2+ is found to be more active than other Fe(III) species for scavenging the conduction band electron of TiO 2 , whereas Fe(III) salt anions also have a great influence [7]. Unfortunately, after all Fe(III) species are transformed into Fe(II), the activity of Fe-containing TiO 2 became to be similar to blank TiO 2 , due to a very slow re-oxidation of Fe(II) back into Fe(III) by O 2 in an acidic medium.…”

Influence of Inorganic Ions and Organic Substances on the Degradation of Pharmaceutical Compound in Water Matrix

“…The inhibition of the oxidation and reduction of the pharmaceutical substance was caused mainly by a competitive adsorption of Cl , CO , HCO and SO anions in the active centers on the catalyst surfaces. In the case where different ions react with positively charged electron holes, the intensity of the generation of hydroxyl radicals, which are mainly responsible for the distribution of contaminants, is lowered [25]. This affects the inhibition of the reaction of oxidation and/or reduction of compounds.…”