Preparation of La2Ti2O7/TiO2/Fe3O4 for effective persulfate activation under simulated sunlight irradiation

Highlights: • La₂Ti₂O₇/TiO₂/Fe₃O₄ is successfully synthesized by a simple hydrothermal method. • The integration between La₂Ti₂O₇ and TiO₂ suppresses the recombination of photo-induced carriers. • The photo-induced electrons accelerate the redox cycle of Fe(III)/Fe(II) for the PS activation. In this study, TiO₂ nanosheets are employed as a template to prepare La₂Ti₂O₇/TiO₂ (TL), which is further modified by Fe₃O₄ to form a ternary catalyst La₂Ti₂O₇/TiO₂/Fe₃O₄ (TLF). The as-synthesized composite is confirmed by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis DRS spectra. According to the catalytic employment of TLF for the activation of persulfate (PS) in assistance of simulated sunlight, it is shown that TLF/PS/light system is able to degrade 93.7% tetracycline hydrochloride, giving 79.8% chemical oxygen demand (COD) removal in assistance of simulated solar light, both of which are apparently greater than that of La₂Ti₂O₇/TiO₂ and Fe₃O₄. The highly improved degradation efficiency can be ascribed to the fact the photo-induced electrons greatly accelerate the redox cycle of Fe(III)/Fe(II) during the PS activation. Besides, the heterojunction constructed between La₂Ti₂O₇ and TiO₂ that significantly suppresses the recombination of photo-excited carriers also contributes to the ameliorated catalytic performance.