title: Sulfate radical-based oxidation of antibiotics sulfamethazine, sulfapyridine, sulfadiazine, sulfadimethoxine, and sulfachloropyridazine: Formation of SO2extrusion products and effects of natural organic matter.
abstract: The widespread occurrence of sulfonamide antibiotics in the environment has raised great concerns about their potential to proliferate antibacterial resistance. Sulfate radical (SO4•-) based advanced oxidation processes (SR-AOPs) are promising in-situ chemical oxidation (ISCO) technologies for remediation of soil and groundwater contaminated by antibiotics. The present study reported that thermally activated persulfate oxidation of sulfonamides (SAs) bearing six-membered heterocyclic rings, e.g., sulfamethazine (SMZ), sulfapyridine (SPD), sulfadiazine (SDZ), sulfadimethoxine (SDM), and sulfachloropyridazine (SCP), all produced SO2extrusion products (SEPs), a phenomenon that is of potential importance, but not systematically studied. As an electrophilic oxidant, SO4•-tends to attack the aniline moiety, the reactive site of SAs, via electro-transfer mechanism. The resulting anilinyl radical cations are subjected to further intermolecular Smiles-type rearrangement to produce SEPs. Formation of SEPs is expected to occur in other SR-AOPs as well. The temperature-dependent evolution pattern of SEP of SMZ, 4-(2-imino-4,6-dimethylpyrimidin-1(2H)-yl)aniline, can be well fitted by kinetic modeling concerning sequential formation and transformation of intermediate product. The presence of natural organic matter (NOM) influenced the evolution patterns of 4-(2-imino-4,6-dimethylpyrimidin-1(2H)-yl)aniline significantly. Toxicological effects of SEPs on ecosystem and human health remain largely unknown, thus, further monitoring studies are highly desirable.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: yuefeiji@njau.edu.cn.
authors.forename: Yuefei
authors.initials: Y
authors.lastname: Ji
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Shi
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: jhlu@njau.edu.cn.
authors.forename: Junhe
authors.initials: J
authors.lastname: Lu
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Ferronato
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, France. Electronic address: jean-marc.chovelon@ircelyon.univ-lyon1.fr.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Chovelon
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D010084:Oxidation-Reduction; D013410:Sulfachlorpyridazine; D013411:Sulfadiazine; D013412:Sulfadimethoxine; D013418:Sulfamethazine; D013427:Sulfapyridine; D013431:Sulfates / Q000378:metabolism*; D013458:Sulfur Dioxide / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D013431:Sulfates; C069025:sulfate radical; D013411:Sulfadiazine; D013458:Sulfur Dioxide; D013412:Sulfadimethoxine; D013418:Sulfamethazine; D013410:Sulfachlorpyridazine; D013427:Sulfapyridine
keywords: Persulfate; SO(2) extrusion products; Smiles-type rearrangement; Sulfate radical-based oxidation; Sulfonamide antibiotics