Department of Inorganic Chemistry, Faculty of Science, University of Granada, 18071, Granada, Spain; Center of Postgraduate Research and Studies, Faculty of Engineering, University Autonomous of San Luis Potosí, Av. Dr. M. Nava No. 8, San Luis Potosí, 78290, Mexico.
Department of Inorganic Chemistry, Faculty of Science, University of Granada, 18071, Granada, Spain.
J Environ Manage. 2020 Feb 1;255:109927. doi: 10.1016/j.jenvman.2019.109927. Epub 2019 Dec 26.
This study was aimed at the degradation of sulfonamides (SNs) via oxidation with Fe(VI). The reaction kinetics, identification of degradation byproducts and their toxicity were investigated. The pH solution and Fe(VI) loading had significant effects on the degradation of the sulfonamides. The maximum degradation rate occurred at pH 3.0 with a 6:1 ratio Fe(VI): sulfonamide, obtaining 100% degradation of 15 mg L SN within 5 min. Although Fe(VI) also showed an appreciable reactivity towards SNs (k = 9.85-19.63 × 10 M s) at pH 7. The influence of solution pH on the values of k can be explained considering the specific reaction between Fe(VI) and SNs. Degradation rates are also influenced by the presence of inorganic ions in different water matrixes. For this reason, ions present in groundwater enhanced the SNs degradation through a synergistic effect among carbonates, sulfates and Fe(VI). Degradation byproducts identified, through UPLC analysis, allowed us to proposed three degradation pathways depending on pH. At acid pH there is a cleavage of C-S and S-N bonds. At neutral pH nitroso and nitro-derivates are formed. At basic pH hydroxylation is the main reaction. The cytotoxicity assay of HEK-293 and J774 cell lines exposed to Fe(VI) indicated that transformation byproducts had a lower toxicity than SNs as baseline products. Accordingly, this research suggests that Fe(VI) can act as a chemical oxidant to remove SNs antibiotics and it can be used to treat antibiotic pollution in wastewater.
本研究旨在通过 Fe(VI)氧化来降解磺胺类药物（SNs）。考察了反应动力学、降解产物的鉴定及其毒性。pH 值溶液和 Fe(VI)负载对磺胺类药物的降解有显著影响。在 pH 3.0 时，Fe(VI):磺胺类药物的比例为 6:1，最大降解速率下，在 5 min 内可将 15 mg/L 的 SN 完全降解。尽管在 pH 7 时，Fe(VI)对 SNs 也具有相当可观的反应活性（k=9.85-19.63×10M s）。考虑到 Fe(VI)和 SNs 之间的特定反应，可以解释溶液 pH 值对 k 值的影响。降解速率也受到不同水基质中无机离子的影响。因此，地下水存在的离子通过碳酸盐、硫酸盐和 Fe(VI)之间的协同作用增强了 SNs 的降解。通过 UPLC 分析鉴定的降解产物使我们能够根据 pH 值提出三种降解途径。在酸性 pH 值下，C-S 和 S-N 键断裂。在中性 pH 值下，形成亚硝基和硝基衍生物。在碱性 pH 值下，羟基化是主要反应。暴露于 Fe(VI)的 HEK-293 和 J774 细胞系的细胞毒性测定表明，转化产物的毒性低于作为基线产物的 SNs。因此，这项研究表明，Fe(VI)可以作为一种化学氧化剂来去除 SNs 抗生素，并可用于处理废水中的抗生素污染。
