School of Environment, Harbin Institute of Technology, Harbin 150090, PR China; College of Environment and Ecology, Chongqing University, Chongqing 400045, PR China.
School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
Water Res. 2023 Oct 1;244:120500. doi: 10.1016/j.watres.2023.120500. Epub 2023 Aug 18.
Although permanganate (Mn(VII)) is extensively utilized as a strong oxidizer for the purification of water, the direct reaction rates between some refractory pollutants and Mn(VII) are moderate or relatively low. In this study, we found that 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO), could act as a redox mediator to enhance bisphenol A (BPA) degradation by Mn(VII) at pH 5.0 - 9.0, with a removal higher than 80% over 5 min. Moreover, the Mn(VII)/PTIO system is highly efficient toward a broad spectrum of contaminants. Mechanism was elucidated as following: PTIO was oxidized by Mn(VII) to PTIO, an oxoammonium cation. As a newly generated reactive species, PTIO could oxidize organics and be reduced to PTIOH (PTIO hydroxylamine) or PTIO simultaneously. The redox cycle of PTIO in consecutive runs as an electron shuttle proved its stability and reusability in Mn(VII) oxidation. In addition to being an electron shuttle, PTIO also acts as an activator of Mn(VII) to promote the production of MnO, which plays a vital role in enhancing BPA abatement at the acidic condition. For the purpose of further understanding the interaction between PTIO and target contaminants, three corresponding degradation pathways for BPA were proposed. Notably, the transformation products of BPA coupling with PTIO were detected, indicating PTIO inhibited the self-coupling of BPA and facilitated the ring-opening pathway. In addition, the ubiquitous humic acid has a positive effect on the Mn(VII)/PTIO system, suggesting a high promise of this system for practical application.
尽管高锰酸盐（Mn(VII)）被广泛用作水净化的强氧化剂，但一些难处理污染物与 Mn(VII)之间的直接反应速率适中或相对较低。在这项研究中，我们发现 2-苯基-4,4,5,5-四甲基恶唑啉-3-氧化物-1-氧（PTIO）可以作为氧化还原介体，在 pH 值为 5.0-9.0 时增强 Mn(VII)对双酚 A（BPA）的降解作用，在 5 分钟内去除率高于 80%。此外，Mn(VII)/PTIO 体系对广谱污染物具有很高的效率。机理如下：PTIO 被 Mn(VII)氧化为 PTIO，一种氧铵阳离子。作为一种新生成的活性物质，PTIO 可以氧化有机物并同时还原为 PTIOH（PTIO 羟胺）或 PTIO。PTIO 在连续运行中的氧化还原循环作为电子穿梭体证明了其在 Mn(VII)氧化中的稳定性和可重复使用性。除了作为电子穿梭体外，PTIO 还可以作为 Mn(VII)的激活剂，促进 MnO 的生成，这在增强酸性条件下 BPA 的去除方面起着至关重要的作用。为了进一步了解 PTIO 与目标污染物之间的相互作用，提出了三种相应的 BPA 降解途径。值得注意的是，检测到了与 PTIO 偶联的 BPA 转化产物，表明 PTIO 抑制了 BPA 的自偶联并促进了开环途径。此外，普遍存在的腐殖酸对 Mn(VII)/PTIO 体系有积极影响，表明该体系在实际应用中有很高的应用前景。
