MnO2 胶体和 Mn(III) 在高锰酸盐氧化有机污染物过程中的作用,Environmental Science & Technology

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MnO2 胶体和 Mn(III) 在高锰酸盐氧化有机污染物过程中的作用
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2022-12-30 , DOI: 10.1021/acs.est.2c07399
Shuchang Wang ₁ , Jie Chen ₁ , Yuankui Sun ₂ , Bo Sun ₃ , Junlian Qiao ₁ , Xiaohong Guan _{1,

2}

Affiliation

尽管在高锰酸盐 (Mn(VII)) 与水中有机污染物的反应过程中会生成中间体锰物质，但原位生成的 MnO ₂胶体在 Mn(VII) 氧化过程中的作用仍存在争议，Mn( III) 在很大程度上被忽视了。本研究表明表观二阶速率常数 ( k _app) 甲基苯基亚砜和卡马西平的 Mn(VII) 氧化随时间保持不变。然而，Mn(VII) 对四种选定酚类污染物的降解分别在 pH 3.0-6.0 和 pH 7.0-9.0 时表现出自加速趋势和线性趋势。多条证据表明，Mn(VII) 氧化过程中自加速趋势的出现归因于酚类有机物被 MnO ₂胶体氧化。焦磷酸盐对 MnO ₂胶体氧化不同有机污染物的影响表明，在特定反应条件下，Mn(III) 也是 Mn(VII) 自动加速氧化有机污染物的原因。动力学模型显示 MnO _{2的总体贡献}在 Mn(VII) 对酚类污染物的自动加速氧化过程中，胶体和 Mn(III) 的含量在 6.6-67.9% 之间。这些发现促进了对 MnO ₂胶体和 Mn(III) 在 Mn(VII) 氧化过程中的作用的理解。

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Roles of MnO2 Colloids and Mn(III) during the Oxidation of Organic Contaminants by Permanganate

Although intermediate manganese species can be generated during the reactions of permanganate (Mn(VII)) with organic pollutants in water, the role of the in situ generated MnO₂ colloids in the Mn(VII) oxidation process remained controversial and the contribution of Mn(III) was largely neglected. This study showed that the apparent second-order rate constants (k_app) of Mn(VII) oxidation of methyl phenyl sulfoxide and carbamazepine remained constant with time. However, the degradation of four selected phenolic contaminants by Mn(VII) exhibited an autoaccelerating trend and a linear trend at pH 3.0–6.0 and pH 7.0–9.0, respectively. Multiple lines of evidence revealed that the occurrence of the autoaccelerating trend in the Mn(VII) oxidation process was ascribed to the oxidation of the phenolic organics by MnO₂ colloids. The influence of pyrophosphate on the oxidation of different organic contaminants by MnO₂ colloids suggests that Mn(III) was also responsible for the autoaccelerating oxidation of organic contaminants by Mn(VII) under specific reaction conditions. The kinetic models revealed that the overall contributions of MnO₂ colloids and Mn(III) ranged within 6.6–67.9% during the autoaccelerating oxidation of phenolic contaminants by Mn(VII). These findings advance the understanding of the roles of MnO₂ colloids and Mn(III) in the Mn(VII) oxidation process.

更新日期：2022-12-30

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