School of Environment, Harbin Institute of Technology, Harbin150090, P.R. China.
Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado80401, United States.
Environ Sci Technol. 2023 Nov 28;57(47):18473-18482. doi: 10.1021/acs.est.2c08141. Epub 2023 Feb 2.
Permanganate (Mn(VII)) is extensively applied in water purification due to its stability and ease of handling, but it is a mild oxidant for trace organic contaminants (TrOCs). Hence, there is significant interest in strategies for enhancing reaction kinetics, especially in combination with efficient and economical carbocatalysts. This study compared the performance of four carbocatalysts (graphite, graphene oxide (GO), reduced-GO (rGO), and nitrogen-doped rGO (N-rGO)) in accelerating sulfisoxazole (SSX) oxidation by Mn(VII) and found that GO exhibited the greatest catalytic performance. Besides, the Mn(VII)/GO system shows desirable capacities to remove a broad spectrum of TrOCs. We proposed that the degradation of SSX in Mn(VII)-GO suspensions follows two routes: (i) direct oxidation of SSX by Mn species [both Mn(VII) and formed MnO] and (ii) a carbocatalyst route, where GO acts as an electron mediator, accepting electrons from SSX and transferring them to Mn(VII). We developed a mathematical model to show the contribution of each parallel pathway and found one-electron transfer is primarily responsible for accelerating SSX removal in the Mn(VII)/GO system. Findings in this study showed that GO provides a simple and effective strategy for enhancing the reactivity of Mn(VII) and provided mechanistic insights into the GO-catalyzed redox reaction between SSX and Mn(VII).
高锰酸盐（Mn(VII)）因其稳定性和易于处理而被广泛应用于水净化，但它对痕量有机污染物（TrOCs）是一种温和的氧化剂。因此，人们对增强反应动力学的策略非常感兴趣，尤其是与高效、经济的碳催化剂结合使用。本研究比较了四种碳催化剂（石墨、氧化石墨烯（GO）、还原氧化石墨烯（rGO）和氮掺杂 rGO（N-rGO））在加速 Mn(VII)氧化磺胺二甲嘧啶（SSX）方面的性能，发现 GO 表现出最大的催化性能。此外，Mn(VII)/GO 体系具有去除广谱 TrOCs 的理想能力。我们提出，Mn(VII)-GO 悬浮液中 SSX 的降解遵循两条途径：（i）Mn 物种[Mn(VII)和形成的 MnO]直接氧化 SSX，（ii）碳催化剂途径，其中 GO 作为电子介体，从 SSX 接受电子并将其转移到 Mn(VII)。我们开发了一个数学模型来显示每个平行途径的贡献，并发现单电子转移主要负责加速 Mn(VII)/GO 体系中 SSX 的去除。本研究的结果表明，GO 为增强 Mn(VII)的反应性提供了一种简单有效的策略，并为 GO 催化 SSX 和 Mn(VII)之间的氧化还原反应提供了机理见解。
