Constructing green and sustainable advanced oxidation processes (AOPs) for the degradation of organic contaminants is of great importance but still remains big challenge. In this work, an effective AOP (MnFeO-activated periodate, MnFeO/PI) was established and investigated for the oxidation of organic contaminants. To avoid the severe aggregation of MnFeO nanoparticles, a hybrid MnFeO-biochar catalyst (MnFeO-BC) was further synthesized by anchoring MnFeO nanoparticles on chemically inert biochar substrate. Intriguingly, MnFeO-BC/PI exhibited different selectivity towards organic contaminants compared with MnFeO/PI, revealing that biochar not only served as the substrate, but also directly participated into the oxidation process. Electron-transfer mechanism was comprehensively elucidated to be responsible for the abatement of pollutants in both MnFeO/PI and MnFeO-BC/PI. The surface oxygen vacancies (OVs) of MnFeO were identified as the active sites for the formation of high potential complexes MnFeO-PI*, which could directly and indirectly degrade the organic pollutants. For the hybrid MnFeO-BC catalyst, biochar played multiple roles: (i) substrate, (ii) provided massive adsorption sites, (iii) electron-transfer mediator. The differences in selectivity of MnFeO/PI and MnFeO-BC/PI were determined by the adsorption affinity between biochar substrate and organics. Overall, the findings of this study expand the knowledge on the selectivity of PI-triggered AOPs.

中文翻译：

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生物炭通过作为电子转移介体改变 MnFe2O4 激活高碘酸盐过程的选择性


构建绿色和可持续的高级氧化工艺（AOP）来降解有机污染物非常重要，但仍然是巨大的挑战。在这项工作中，建立并研究了一种有效的 AOP（MnFeO 激活高碘酸盐，MnFeO/PI），用于有机污染物的氧化。为了避免 MnFeO 纳米颗粒的严重聚集，通过将 MnFeO 纳米颗粒锚定在化学惰性生物炭基质上，进一步合成了混合 MnFeO-生物炭催化剂（MnFeO-BC）。有趣的是，与MnFeO/PI相比，MnFeO-BC/PI对有机污染物表现出不同的选择性，表明生物炭不仅充当底物，而且直接参与氧化过程。电子转移机制被全面阐明，是 MnFeO/PI 和 MnFeO-BC/PI 中污染物减少的原因。 MnFeO的表面氧空位（OV）被认为是形成高电位络合物MnFeO-PI*的活性位点，可以直接或间接降解有机污染物。对于混合 MnFeO-BC 催化剂，生物炭发挥多种作用：（i）基质，（ii）提供大量吸附位点，（iii）电子转移介体。 MnFeO/PI 和 MnFeO-BC/PI 选择性的差异由生物炭基质和有机物之间的吸附亲和力决定。总体而言，本研究的结果扩展了对 PI 触发的 AOP 选择性的认识。