Abstract
Owing to its low eco-toxicity and low cost, sulfite is considered a promising precursor for oxysulfur radicals. In this study, we report the rapid degradation of ciprofloxacin in water using a derivative of an iron-based metal–organic framework catalyst (S-MIL-101(Fe)) for the heterogeneous activation of sulfite. S-MIL-101(Fe) possessed a similar structure to the original MIL-101(Fe), and more active sites were exposed. Unlike previous systems used to activate sulfite with Fe-based catalysts, this system exhibited excellent performance under alkaline conditions. Ciprofloxacin (10 mg/L) removal efficiency of 94.7 % was observed at pH 8.7, implying a different activation mechanism. It is suggested that the iron coordinatively unsaturated metal sites (Fe CUSs) on the surface of S-MIL-101(Fe) can effectively complex with SO32− to form Fe(III) CUS-SO3+, followed by the generation of SO3− through single-electron transfer. Quenching and electron paramagnetic resonance experiments demonstrated that SO3−, O2−, SO5− and OH were involved in the degradation of ciprofloxacin, in which SO3− played a significant role. Moreover, HSO5− (peroxymonosulfate ion), an important product produced during the sulfite activation process, also participated in the formation of free radicals. This study complements the mechanism of heterogeneous activation of sulfites by Fe-based materials and reinforces the important role played by SO3− in some cases. The influence of chloride, bicarbonate, nitrate, and humic acid on ciprofloxacin elimination was minimal. In addition, this system could operate efficiently in real water environments.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.