Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, P. R. China.
School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia.
Environ Sci Technol. 2021 Dec 7;55(23):16078-16087. doi: 10.1021/acs.est.1c02042. Epub 2021 Oct 11.
Graphitized nanodiamonds (ND) exhibit outstanding capability in activating peroxymonosulfate (PMS) for the removal of aqueous organic micropollutants (OMPs). However, controversial observation and interpretation regarding the effect of graphitization degree on ND's activity and the role of singlet oxygen (O) in OMP degradation need to be clarified. Herein, we investigated graphitized ND-mediated PMS activation. Experiments show that the activity of ND increases first and then decreases with the monotonically increased graphitization degree. Further experimental and theoretical studies unveil that the intensified surface graphitization alters the degradation mechanism from singlet oxygenation to an electron-transfer pathway. Moreover, for the first time, we applied a self-constructed, time-resolved phosphorescence detection system to provide direct evidence for O production in the PMS-based system. This work not only elucidates the graphitization degree-dependent activation mechanism of PMS but also provides a reliable detection system for in situ analysis of O in future studies.
石墨化纳米金刚石（ND）在激活过一硫酸盐（PMS）去除水中有机微量污染物（OMPs）方面表现出卓越的能力。然而，关于石墨化程度对 ND 活性的影响以及单线态氧（O）在 OMP 降解中的作用，仍需要澄清一些有争议的观察结果和解释。在此，我们研究了石墨化 ND 介导的 PMS 激活。实验表明，ND 的活性随着石墨化程度的单调增加而先增加后减少。进一步的实验和理论研究揭示，表面石墨化的增强改变了降解机制，从单线态氧合作用转变为电子转移途径。此外，我们首次应用自行构建的时间分辨磷光检测系统，为 PMS 体系中 O 的生成提供了直接证据。这项工作不仅阐明了 PMS 依赖石墨化程度的激活机制，而且为今后研究中 O 的原位分析提供了可靠的检测系统。
