Modified ilmenite as catalyst for CWPO-Photoassisted process under LED light

JUAN A. ZAZO; JOSÉ A. CASAS; PATRICIA GARCÍA-MUÑOZ; BIBIANA P. BARBERO; GEMA PLIEGO; ANA BAHAMONDE

CHEMICAL ENGINEERING JOURNAL

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2017 vol. 318 p. 89 - 94

1385-8947

The influence of the iron chemical nature contained in ilmenite (FeTiO3) upon the activity and stability of these materials as catalysts for CWPO-Photoassisted process under LED light (λ: 405 nm) were evaluated. Raw ilmenite was treated with H2 within the range 25-1000°C in order to partially reduce iron oxides to Fe(0). The catalysts were characterized by N2 adsorption/desorption, TXRF, XRD and XPS analysis. The co-presence of different iron species (Fe(0), Fe(II) and Fe(III)) along with the light effect over material surface, led to an increase of H2O2 decomposition rate into HO・ and, therefore, a higher oxidation rate. In all case, after total H2O2 depletion, a complete phenol degradation and a 95% TOC conversion was reached in batch at pH0=3 and 50°C using the stoichiometric H2O2 dose (14 mol H2O2/mol phenol) and 10 W・m-2 LED light. Long-term continuous experiments were carried out to assess the stability and the lifetime of the catalyst. The higher reduction degree led to a higher organic matter mineralization but also to a higher leaching of active phase (around 3% of the total iron amount in ilmenite. Nevertheless, catalyst deactivation seems to be related to the oxidation of iron on the catalyst surface.