Degradation and mineralization of 4-tert-butylphenol in water using Fe-doped TiO₂ catalysts

Abstract

In the present work, the photocatalytic degradation and mineralization of 4-tert-butylphenol in water was studied using Fe-doped TiO₂ nanoparticles under UV light irradiation. Fe-doped TiO₂ catalysts (0.5, 1, 2 and 4 wt.%) were prepared using wet impregnation and characterized via SEM/EDS, XRD, XRF and TEM, while their photocatalytic activity and stability was evaluated via total organic carbon, 4-tert-butylphenol, acetic acid, formic acid and leached iron concentrations measurements. The effect of H₂O₂ addition was also examined. The 4% Fe/TiO₂ demonstrated the highest photocatalytic efficiency in terms of total organic carbon removal (86%). The application of UV/H₂O₂ resulted in 31% total organic carbon removal and 100% 4-t-butylphenol conversion; however combining Fe/TiO₂ catalysts with H₂O₂ under UV irradiation did not improve the photocatalytic performance. Increasing the content of iron on the catalyst from 0.5 to 4% considerably decreased the intermediates formed and increased the production of carbon dioxide. The photocatalytic degradation of 4-tert-butylphenol followed pseudo-second order kinetics. Leaching of iron was observed mainly in the case of 4% Fe/TiO₂, but it was considered negligible taking into account the iron load on catalysts. The electric energy per order was found in the range of 28–147 kWh/m³/order and increased with increasing the iron content of the catalyst.