Efficient degradation of cefotaxime by a UV+ferrihydrite/TiO 2 +H 2 O 2 process: the important role of ferrihydrite in transferring photo‐generated electrons from TiO 2 to H 2 O 2

BACKGROUND: Developing effective removal processes for antibiotics has attracted increasing interest recently. In this work, a novel strategy involving the combination of photocatalysis with Fenton reaction using ferrihydrite/TiO₂ (Fh/TiO₂) nanohybrids was developed to efficiently degrade the antibiotic cefotaxime. Fh/TiO₂ nanohybrids were synthesized by simply growing Fh on the surface of commercially available TiO₂. We expected that Fh of Fh/TiO₂ could capture photo‐generated electrons from TiO₂, inhibiting the recombination of electron–hole pairs; also, by virtue of Fe(III)/Fe(II) cycle on Fh/TiO₂, photo‐generated electrons could be continually transferred to H₂O₂ to produce ·OH. Accordingly, high degradation efficiency of cefotaxime could be achieved. RESULTS: With UV light and H₂O₂, Fh/TiO₂ with a Fe/Ti molar radio of 7% showed high catalytic activity indeed, and its degradation rate for cefotaxime was nearly three times higher than that of TiO₂. The decomposition of H₂O₂ and production of ·OH in the UV+7%Fh/TiO₂+H₂O₂ system were also increased markedly. The large amount of Fe(II) on 7%Fh/TiO₂ determined in this system supported our hypothesis that Fh of 7%Fh/TiO₂ could capture photo‐generated electrons from TiO₂. Although dissolved iron was observed, the contribution of Fenton reaction by dissolved iron was rather limited. After four consecutive cycles, 7%Fh/TiO₂ still retained good stability. CONCLUSIONS: The UV+7%Fh/TiO₂+H₂O₂ system provides a potential alternative in degradation of cefotaxime for further practical application, and it has the following advantages: high catalytic activity, simple preparation method, good stability and low cost, as well as continued catalytic activity after total consumption of H₂O₂. © 2019 Society of Chemical Industry