Effect of different light sources on phenol degradation using a metal-doped TiO2 catalyst

LUCIA ROSSI; MAGDALENA PALACIO; PAULA I. VILLABRILLE; MARCELA V. MARTIN; JANINA A. ROSSO

Villa Carlos Paz

Encuentro; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2017

Conventional methods of treating industrial effluents can not effectively remove refractory contaminants, such as phenols. An alternative treatment is the use of advanced oxidation processes. Many of them are based on the use of TiO2 as a photocatalyst [1]. However, the use of TiO2 has several limitations. It has been found that the modification of this material with metals (noble, transition or lanthanide) shown an enormous potential to overcome the pristine TiO2 particles limitations of visible light absorption and high recombination of charge carriers [2,3]. The aim of this work is to study the effect of different light sources on phenol degradation (model contaminant) using metal-doped TiO2 catalysts (metal: V, Pd or Ce, 0.1 at.%). The materials were prepared by the sol-gel method. The procedure was described in a previous paper [4].The specific reagents used in this synthesis were: titanium tetraisopropoxide (TTIP), absolute ethanol, nitric acid and, cerium(III) nitrate hexahydrate (Ce(NO3)3.6H2O), palladium acetylacetonate (Pd(acac)2) or vanadyl acetylacetonate (VO(acac)2) as metal-ion precursor.X-ray diffraction analysis exhibited only anatase phase in all samples, with crystallite size between 6.8 and 10.1 nm (estimated by Scherrer equation). The BET surface area values were between 80 and 110 m2g-1 (N2 physisorption). The diffuse reflectance spectra of metal-doped TiO2 catalysts showed a band broadening to the visible region over the range of 400-800 nm, with EGAP values between 1.9 and 2.3 eV. Degradation of phenol in aqueous solution ([phenol]0= 50 μM) was studied with irradiation of different light sources (Rayonet RPR-100 with UV or visible lamps) and 1 gL-1 of each catalyst. In all cases, periodic sampling was carried out. The concentration of phenol and reaction intermediates were determined by HPLC (HP 1050). The Figure 1 shows the percentage of phenol degradation with each catalyst after 3 or 5 hours under UV or visible irradiation, respectively. All the materials presented photoactivity while the efficiency with UV lamps was higher than with visible lamps. It is noteworthy that 0.1Pd catalyst reached total degradation with UV lamps after 2 hours of irradiation.