Anhui Province Key Laboratory of Value-Added Catalytic Conversion and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Tunxi Road 193, Hefei 230009, China.
Anhui Province Key Laboratory of Value-Added Catalytic Conversion and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Tunxi Road 193, Hefei 230009, China.
Water Res. 2024 Oct 15;264:122224. doi: 10.1016/j.watres.2024.122224. Epub 2024 Aug 16.
Manganese dioxide (MnO), renowned for its abundant natural crystal phases, emerges as a leading catalyst candidate for the degradation of pollutants. The relationship between its crystal phase and catalytic activity, particularly for periodate activation, has remained both ambiguous and contentious. This study delineates the influence of various synthetic MnO phase structures on their capabilities in catalyzing periodate-assisted pollutant oxidation. Five distinct MnO phase structures (α-, β-, γ-, δ-, and ε-MnO₂) were prepared and evaluated to activate periodate and degrade pollutants, following the sequence: α-MnO₂ > γ-MnO₂ > β-MnO₂ > ε-MnO₂ > δ-MnO₂. Through quenching experiments, electron paramagnetic resonance tests, and in situ electrochemical studies, we found an electron transfer-mediated process drive pollutant degradation, facilitated by a highly reactive metastable intermediate complex (MnO₂/PI*). Quantitative structure-activity relationship analysis further indicated that degradation efficiency is strongly associated with both the crystal phase and the Mn (IV) content, highlighting it as a key active site. Moreover, the α-MnO₂ phase demonstrated exceptional recycling stability, enabling an effective pollutant removal in a continuous flow packed-bed reactor for 168 h. Thus, α-MnO₂/PI proved highly effective in mineralizing organic pollutants and reducing their toxicities, highlighting its significant potential for environmental remediation.
二氧化锰（MnO）以其丰富的天然晶体相而闻名，是一种很有前途的催化剂候选物，可用于污染物的降解。其晶体相与其催化活性之间的关系，特别是对高碘酸盐的激活，一直是模糊和有争议的。本研究阐述了不同合成 MnO 相结构对其在催化高碘酸盐辅助污染物氧化能力的影响。制备了五种不同的 MnO 相结构（α-、β-、γ-、δ-和 ε-MnO₂）并进行了评估，以激活高碘酸盐并降解污染物，其顺序为：α-MnO₂＞γ-MnO₂＞β-MnO₂＞ε-MnO₂＞δ-MnO₂。通过淬灭实验、电子顺磁共振测试和原位电化学研究，我们发现电子转移介导的过程驱动污染物降解，这是由高反应性亚稳态中间络合物（MnO₂/PI*）促成的。定量构效关系分析进一步表明，降解效率与晶体相和 Mn（IV）含量密切相关，这表明它是一个关键的活性位点。此外，α-MnO₂相表现出出色的循环稳定性，可在连续流动填充床反应器中有效去除污染物 168 小时。因此，α-MnO₂/PI 被证明在矿化有机污染物和降低其毒性方面非常有效，这突显了其在环境修复方面的巨大潜力。
