RESUMO
In this study, TiO2 supported over embryonic Beta zeolite (BEA) was prepared for the photocatalytic degradation of Tetracycline (TC) antibiotic under visible light. The immobilization of sol-gel TiO2 over the zeolite increased its surface area from 33 (m2/g) to 226 (m2/g) and enhanced its adsorption efficiency from 8 % to 18 %. In order to expand the photocatalytic activity of TiO2 towards the visible light region (i.e. λ > 380 nm), two different metal sensitization techniques with Iron ions from aqueous solution of FeCl3 were explored. In the ion-exchange method, the substitutional cations within the TiO2/BEA structure were exchanged with Fe3+. Whereas, in the doping technique, solgel TiO2 was doped with Fe3+ during its synthesis and before its immobilization over Zeolite. Four different samples with 20, 40, 60, and 100 % w/w of TiO2/BEA ratio were prepared. After testing the various ion-exchanged photocatalysts under blue and white lights, only Fe-60%TiO2/BEA showed better activity compared to pure TiO2 under white light at TC initial concentration, C o = 20 ppm. For the doped immobilized Titania with 60 wt% TiO2/BEA, three different doped photocatalysts were prepared with 3 %, 7 %, and 10 % per mole Fe/TiO2. All the Fe-doped TiO2/BEA photocatalysts showed better activity compared to pure TiO2 under white light. Under solar irradiations, the 3 % Fe-doped TiO2/BEA was able to degrade all TC within 120 min, while Fe-60%TiO2/BEA needed 200 min, and TiO2 needed more than 300 min. This enhanced performance was a result of both increased surface area due to immobilization over BEA as well as iron doping by Fe3+ that simultaneously increased the visible light absorption of TiO2 and minimized the charge carrier recombination effect.
