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

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

Villa Carlos Paz

Encuentro; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología ELAFOT2017; 2017

Grupo Argentino de Fotobiología

Conventional methods of treating industrial effluents can noteffectively remove refractory contaminants, such as phenols. An alternativetreatment is the use of advanced oxidation processes. Many of them are based onthe use of TiO2 as a photocatalyst [1]. However, the use of TiO2has several limitations. It has been found that the modification of thismaterial with metals (noble, transition or lanthanide) shown an enormouspotential to overcome the pristine TiO2 particles limitations ofvisible light absorption and high recombination of charge carriers [2,3]. The aimof this work is to study the effect of different light sources on phenol degradation(model contaminant) using metal-doped TiO2 catalysts (metal: V, Pd orCe, 0.1 at.%). The materials were prepared by the sol-gel method. The procedure wasdescribed 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), palladiumacetylacetonate (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-dopedTiO2 catalysts showed a band broadening to the visible region overthe 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 UVor visible lamps) and 1 gL-1 of each catalyst. In all cases, periodicsampling was carried out. The concentration of phenol and reactionintermediates were determined by HPLC (HP 1050). The Figure shows the percentage of phenol degradation with each catalystafter 3 or 5 hours under UV or visible irradiation, respectively. All thematerials presented photoactivity while the efficiency with UV lamps was higherthan with visible lamps. It is noteworthy that 0.1Pd catalyst reached totaldegradation with UV lamps after 2 hours of irradiation