This work investigates the effect of UV-LED on the persulfate (PS) activation with natural ilmenite (FeTiO3) in the oxidation of azo dye Disperse Blue 3 (DB3). The high induction period and the scarce ability of this mineral to activate PS can be overcome by using UV irradiation to increase the SO4 center dot- generation via photoreduction of Fe(III) to Fe((I) on the ilmenite surface, main responsible of SO4 center dot- formation in iron-based catalysis. The effect of several operating conditions such as persulfate dose (20-100% of the theoretical stoichiometric amount), reaction temperature (30-70 degrees C) and mineral concentration 320 mg L-1 has been studied. Under optimum conditions (320 mg L(-1)of ilmenite, pH(0) : 3, using 100% of stoichiometric amount of PS at 70 degrees C under UV-LED radiation) more than 95% TOC reduction and 92% PS decomposition were reached after 180 min. The progressive deactivation of FeTiO3 through successive experiments can be explained, according to density functional theory (DFT) calculations, by the formation of a passivation layer due to adsorption of SO4- on the FeTiO3 surface. (C) 2017 Elsevier B.V. All rights reserved.