Singlet oxygen mediated the selective removal of oxytetracycline in C/Fe3C/Fe0 system as compared to chloramphenicol
Nan Zhao, Kunyuan Liu, Chao He, Jia Gao, Weihua Zhang, Tingjie Zhao, Daniel C.W. Tsang, Rongliang Qiu
Abstract
Reactive oxygen species (ROS) production for Fe0 is limited because of the formed iron corrosion products. In this study, C/Fe3C/Fe0 composite which produces enhanced ROS has been specifically designed and fabricated to remove typical antibiotics (i.e., oxytetracycline (OTC) and chloramphenicol (CAP)) as a heterogeneous Fenton-like catalyst. The C/Fe3C/Fe0 composite demonstrated excellent performance for both OTC and CAP removal as compared with Fe0 and biochar. Furthermore, X-ray photoelectron spectrometry, Fourier transform infrared spectrometry, high performance liquid chromatography-mass spectra and electron spin resonance analyses were conducted to elucidate the adsorption and degradation mechanisms. The adsorption of OTC and CAP was mainly dominated by H bonds and the electron-acceptor-acceptor on the surface of the C/Fe3C/Fe0 composite, respectively. In particular, OH simultaneously induced the degradation of OTC and CAP, while 1O2 presented the selective oxidation to OTC. More specifically, the degradation of OTC over C/Fe3C/Fe0 was stronger and faster than that of CAP, leading to 65.84% and 16.84% of removal efficiency for OTC and CAP, respectively. Furthermore, C/Fe3C/Fe0 exhibited superior reusability and stability after regeneration, but regenerated Fe0 almost lost its reactivity. Therefore, the efficiency in situ generation of 1O2 using C/Fe3C/Fe0 would shed new light on the selective oxidation of aqueous organic compounds.