Distinguishing homogeneous-heterogeneous degradation of norfloxacin in a photochemical Fenton-like system (Fe3O4/UV/oxalate) and the interfacial reaction mechanism.

Title Distinguishing homogeneous-heterogeneous degradation of norfloxacin in a photochemical Fenton-like system (Fe3O4/UV/oxalate) and the interfacial reaction mechanism.
Authors M. Huang; T. Zhou; X. Wu; J. Mao
Journal Water Res
DOI 10.1016/j.watres.2017.03.008
Abstract

This study demonstrated the efficient degradation of a typical bio-refractory antibiotic norfloxacin (NOR) in a photochemical iron oxides/oxalate system adopting magnetic catalyst (Fe3O4/UV/Ox). It was found that the in-situ generated HO was the main reactive oxygen species (ROS) but CO2(-) could also participate in the NOR degradation to form formylate organic intermediates. Besides, NOR would be degraded via an interesting pathway comprising an initial lag and a subsequent rapid period, where the former could be eliminated by introducing the pre-dissolution of Fe3O4 particles. Furthermore, specific comparative investigations and surface characterizations of pre-adsorbed Fe3O4 particles had evidenced that the existence of surface-bound iron-Ox complexes would be critical for the heterogeneous photochemical dissolution of Fe3O4 and effectively initiated the subsequent homogeneous-heterogeneous NOR degradation. Finally, a comprehensive distinguishing reaction mechanism was proposed including a homogeneous-heterogeneous iron cycle on the solid-water interface and a series of homogeneous radical reactions. Therein, complexation instead of photochemical reduction would be dominant during the whole dissolution process even under UV irradiation. Rapid electrons exchange would occur photochemically between Fe(II) and Fe(III) in the octahedral sites, further weakening the surface Fe-O bonds and accelerating its breakaway from the bulk Fe3O4 structure. This work could distinguish the complex heterogeneous/homogeneous reactions in the photochemical in-situ chemical oxidation systems that utilize naturally abundant iron oxides and polycarboxylic acids.

Citation M. Huang; T. Zhou; X. Wu; J. Mao.Distinguishing homogeneous-heterogeneous degradation of norfloxacin in a photochemical Fenton-like system (Fe3O4/UV/oxalate) and the interfacial reaction mechanism.. Water Res. 2017;119:4756. doi:10.1016/j.watres.2017.03.008

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Iron

See more Iron products. Iron (atomic symbol: Fe, atomic number: 26) is a Block D, Group 8, Period 4 element with an atomic weight of 55.845. The number of electrons in each of Iron's shells is 2, 8, 14, 2 and its electron configuration is [Ar] 3d6 4s2. Iron Bohr ModelThe iron atom has a radius of 126 pm and a Van der Waals radius of 194 pm. Iron was discovered by humans before 5000 BC. In its elemental form, iron has a lustrous grayish metallic appearance. Iron is the fourth most common element in the Earth's crust and the most common element by mass forming the earth as a whole. Iron is rarely found as a free element, since it tends to oxidize easily; it is usually found in minerals such as magnetite, hematite, goethite, limonite, or siderite.Elemental Iron Though pure iron is typically soft, the addition of carbon creates the alloy known as steel, which is significantly stronger.

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