Photocatalytic Degradation of Phenol with Fe-Titania Catalysts

Abstract

Iron titanate (FeTiO 3 ) obtained from rich titanium and iron mineral presented some absorption of UV light and photocatalytic activity for the degradation of phenol in aqueous solution. However, most of the reactant is converted to carboxylic acids that remain in the reaction mixture because natural ilmenite do not produce enough HO • radicals to completely mineralize the original reactant at the same rate as pure titania (Degussa P25). The XRD analysis of Fe-titania catalysts prepared by simple mixing of FeTiO 3 and TiO 2 showed that the structure of TiO 2 is not modified when small amounts of FeTiO 3 , in the order of 10% weight, are well mixed with pure titania. Therefore, the photocatalytic activity of these catalysts is not affected by the presence of FeTiO 3 . But, heavy ilmenite particles induce the separation of the catalysts particles after the photocatalytic degradation processes.

Synthesis, characterization, and catalytic activity of FeTiO3/TiO2 for photodegradation of organic pollutants with visible light

“…Then, the energy bandgap of FeTiO 3 may have a value between 2.63 and 3.1 eV. Similar results have been reported previously [31].…”

“…Since phenol and halogenated phenols are used as model compounds to study photocatalytic degradation of organic industrial pollutants [18,31,34], the most active FeTiO 3 /TiO 2 catalysts were also tested for degradation of aqueous solution of 4-chlorophenol. Figure 9a shows the UV-Vis spectra of the reaction samples for photocatalytic degradation of 4-chlorophenol with the 10/90 (FeTiO 3 /TiO 2 ) catalyst.…”

“…It also shows the presence of small amounts of phenol, benzoquinone, and hydroquinone. Previous studies have demonstrated that 4-chlorophenol is transformed to phenol and hydroquinone by abstraction and substitution of the chlorine atom [31,34,35]. Then, these aromatic products can be converted to benzoquinone and benzenetriol, which are transformed to other nonaromatic organic molecules before being mineralized to CO 2 and water.…”

Photocatalytic degradation of paracetamol: Intermediates and total reaction mechanism

“…These experimental results explain the fact that both intermediate compounds are only detected in trace amounts in the photocatalytic degradation of aromatic alcohols. Furthermore, it has been demonstrated by several investigations that hydroquinone oxidation proceeds through different reaction pathways (Scheme 1), generating 1,2,4-trihydroxybenzene and benzoquinone and eventually a mixture of several dicarboxylic acids [33]. A subsequent investigation on the oxidation of PAM promoted by ozonation and UV/H 2 O 2 was reported [20].…”

“…However, the presence of any of these intermediates in the photocatalytic reaction mixture could not account for the observed band with a max at 320 nm. This band is most likely due to the presence of p-nitrophenol since a NO 2 substituent exerts a strong batochromic shift in the (n-* transition) absorption band characteristic of phenol [32][33][34][35][36].…”