第一作者：Fangzhou Li
通讯作者：董恒 副教授/展思辉 教授
通讯单位：南开大学环境科学与工程学院
DOI:10.1016/j.apcatb.2024.124584
生物质衍生碳质材料通过活化过硫酸盐，在微污染物（MPs）的非降解氧化中展现出令人着迷的潜力，其性能主要取决于石墨化的氮。本文利用咖啡残渣合成了一种富含氮空位的类石墨烯材料。该材料在去除二级污水中的四环素类抗生素方面表现出卓越的去除效率（95%）和降解动力学（0.21 min-1），并显著降低了生物毒性。固体非自由基氧化包括电子转移（89%）和单线态氧（1O2）氧化（11%）。通过追踪 1O2 的来源和电子流，发现出现在 N 空位处的酮基是从过二硫酸盐（PDS）中获取电子并产生 1O2 的关键部位。然后，电子在它们之间的微电场驱动下转移到石墨 N 上。这项工作揭示了生物质资源中的空位在高效去除实际水基质中的 MPs 方面的功能。
Fig. 1. (a) Absolute N content and relative graphitic N ratio. (b) High-resolution XPS N 1 s. (c) Raman spectra. (d) EPR spectra. (e) Transformation of N species during high-temperature annealing treatment.
Fig. 2. (a) Comparison of the modified kinetic rate constant K for this work with reported materials. (b) TOC removal and biotoxicity. (c) Disturbance of HA and common inorganic anions on TC degradation in the GNNV-900/PDS system. (d) Molecular structure and removal of four tetracycline antibiotics. (e) Changes in biotoxic equivalents (BTE) of intermediates products during degradation. Experimental conditions: [TC]0=50 mg L−1, [PDS]0=0.5 mM, [GNNV]0=40 mg L−1.
Fig. 3. (a) TC removal by the GNNV-900/PDS in different atmosphere. (b) Effects of MeOH, TBA and p-BQ on TC removal in N2 atmosphere in the GNNV-900/PDS system. (c) Open-circuit potential curves with the addition of PDS and TC on GNNV electrodes. (d) Chronoamperometric curves (i-t) at the open circuit potential. (e) Linear scanning voltametric (LSV) curve with the addition of PDS and TC on GNNV electrodes. (f) Linear correlation between graphitic N and kN2. (g) Adsorption structure and energy of PDS on graphitic N and pyridinic N, and electrostatic potential of graphitic N and pyridinic N, and charge density difference induced by PDS on graphitic N (yellow and blue regions represent the electron accumulation and the electron depletion). Experimental conditions in i-t and LSV measurements: [TC]0=10 mg L−1, [PDS]0=2 mM.
Fig. 4. (a) EPR spectra of DMPOX, DMPO-·O2–, TEMP-1O2 in the GNNV-900/PDS system (b) TEMP-1O2 EPR spectra in H2O and D2O. (c) Effects of MeOH, TBA, p-BQ, and L-his on TC removal in the GNNV-900/PDS system.
Fig. 5. Extracted Ion Chromatogram (EIC) of TEMP18O and TEMP16O generated in (a) N2 atmosphere and (b) 18O2 atmosphere. Spectra of stable isotope ratio mass spectrometry of (c) used GNNV-900 and (d) water sample. Experimental conditions: [TEMP]0=25 mM, [PDS]0=0.5 mM, [GNNV]0=40 mg L−1.
Fig. 6. (a) Linear correlation between kO2 and graphitic N/N vacancy. (b) Linear correlation between kO2–kN2 and N vacancy/edge defect. (c) Adsorption energy of PDS on graphitic N and oxidized N vacancy and charge density difference induced by PDS on oxidized N vacancy (yellow and blue regions represent the electron accumulation and the electron depletion). (d) Proposed nonradical oxidation mechanism of TC in GNNV-900/PDS.
这项工作全面研究了碳/PS-AOP 中 N 空位在消除 MPs 潜在生态风险方面的功能。我们从生物质中合成了一种石墨化氮和氮空位共存的无金属类石墨烯材料（GNNV-900）来激活 PDS。根据实验研究和 DFT 计算的结果，GNNV-900/PDS 进行了完全的非自由基氧化，主要是电子转移，部分是 1O2 氧化。在城市污水处理厂的模拟和实际二级出水中都获得了优异的降解动力学和 TOC/生物毒性去除效率。在溶解的 O2 分子的帮助下，N 空位处出现了原位酮基。它增强了对 PDS 的吸附，并夺取 PDS 的电子产生 1O2。然后，电子转移到石墨 N，并最终被吸附在那里的 PDS 所接受。此外，石墨化 N 和 N 空位之间形成的微电场协同加速了电子转移和 1O2 生成过程中的两种分子内电子流。这项研究阐明了石墨化生物质中 N 空位的重要性，并为以低能耗从实际水基质中去除 MPs 提供了前景广阔且高效的方法。
Fangzhou Li, Lu Sun, Haojie Wang, Heng Dong, Fei Li, Xiaoyan Wu, Sihui Zhan, Crucial role of nitrogen vacancies in carbon activated persulfate toward nonradical abatement of micropollutants from secondary effluent, Applied Catalysis B: Environment and Energy, 2025, https:///10.1016/j.apcatb.2024.124584
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