Sustainable production of Fe-doped MnO2 nanoparticles for accelerated tetracycline antibiotic detoxification

Abstract

Manganese dioxide (MnO₂) has been recognized as one of the natural systems' most active mineral oxidants. However, when it comes to catalytic oxidation of antibiotic applications, pure MnO₂ falls short in delivering satisfactory performance. Hence, a set of Fe³⁺-doped porous MnO₂ (0.02Fe-MnO₂, 0.1Fe-MnO₂, and 0.14Fe-MnO₂) nanoparticles were synthesized here via a convenient and energy-efficient one-step reaction method. A series of experiments revealed that Fe-doping strategy enhances the properties of MnO₂ host by suppressing the crystalline structure, increasing the amount of surface oxygen defects, and modifying the Mn³⁺/Mn⁴⁺ ratio. Specifically, the tetracycline (TC) removal efficiency of 0.14Fe-MnO₂ reaches 92% without the need for any additional co-oxidant, representing a 20% improvement over pristine MnO₂ nanoparticles. Moreover, this process shows a fast dynamic (achieving 70% of TC removal in just 5 min) and demonstrates pH-resistance, maintaining high TC removal efficiency (≥90%) over a wide pH range of 3.0-9.0. Mechanical studies reveal that the degradation of TC can be attributed to the oxidation by reactive oxygen radicals and Mn³⁺, with ¹O₂ being the primary radical involved in the reaction, accounting for 55% of TC removal. Importantly, cytotoxicity testing indicates that the biotoxicity of TC toward organisms can be effectively mitigated using 0.14Fe-MnO₂ nanomaterial. This study presents a readily applicable candidate for economically and conveniently eliminating of environmental TC pollution, thereby reducing the threat posed by TC pollution to the ecosystem.

Keywords: Fe(3+); MnO(2); Oxidation; Tetracycline; pH.