Efficient degradation of cefotaxime by a UV plus ferrihydrite/TiO2+H2O2 process: the important role of ferrihydrite in transferring photo-generated electrons from TiO2 to H2O2

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 center dot 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 center dot 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. (c) 2019 Society of Chemical Industry