Effect of Cu(II) on Mn(II) Oxidation by Free Chlorine To Form Mn Oxides at Drinking Water Conditions
Effect of Cu(II) on Mn(II) Oxidation by Free Chlorine To Form Mn Oxides at Drinking Water Conditions
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饮用水条件下 Cu(II) 对游离氯氧化 Mn(II) 形成氧化锰的影响
DOI：
10.1021/acs.est.9b06497
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发表时间：
2020
影响因子：
11.4
通讯作者：
Giammar Daniel E.
中科院分区：
文献类型：
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作者：
Li Guiwei;Pan Weiyi;Zhang Lili;Wang Ziqiao;Shi Baoyou;Giammar Daniel E.
溶解的Mn（II）到Mn（III/IV）氧化物（MnOx）的化学氧化可导致饮用水分配系统中Mn沉积物的积累。然而，Mn（II）被游离氯氧化在温和条件下（例如，pH 7.7和1.0 mg/L Cl 2）。这项研究发现了一个显着的作用，铜（II）在锰（II）的氧化条件下有关的氯化饮用水的供应。在pH 7.7时，20 μg/L的溶解态Cu（II）对Mn（II）的氧化有10倍以上的促进作用。固体表征表明，在Mn（II）氧化过程中，Cu（II）吸附到新形成的MnOxand产生Mn-Cu混合物（表示为MnOx-Cu（II））。反应动力学的自催化模型表明，新鲜形成的MnOx-Cu（II）具有比纯MnOx高得多的催化活性。固体CuO也催化Mn（II）的氧化，动力学模型表明，在CuO表面促进Mn（II）的初始氧化后，CuO表面上的新鲜形成的MnOx-Cu（II）在加速进一步Mn（II）氧化中起主导作用。这项研究表明，锰氧化物的形成在饮用水分配系统的位置或在前提管道Mn（II）和Cu（II）都可用的高潜力。它提供了深入了解其他金属与锰沉积物的共存，这是经常观察到的分配系统。
The chemical oxidation of dissolved Mn(II) to Mn(III/IV) oxides (MnOx) can lead to the accumulation of Mn deposits in drinking water distribution systems. However, Mn(II) oxidation by free chlorine is quite slow under mild conditions (e.g., pH 7.7 and 1.0 mg/L Cl2). This study found a significant role for Cu(II) in Mn(II) oxidation under conditions relevant to the supply of chlorinated drinking water. At pH 7.7, dissolved Cu(II) accelerated Mn(II) oxidation more than 10 times with a dose of 20 μg/L. Solid characterization revealed that during Mn(II) oxidation, Cu(II) adsorbed to freshly formed MnOxand produced Mn–Cu mixtures (denoted as MnOx–Cu(II)). An autocatalytic model for the reaction kinetics suggested that the freshly formed MnOx–Cu(II) had a much higher catalytic activity than that of pure MnOx. Solid CuO also catalyzed Mn(II) oxidation, and kinetic modeling indicated that after an initial oxidation of Mn(II) facilitated by the CuO surface, the freshly formed MnOx–Cu(II) on CuO surface played the dominant role in accelerating further Mn(II) oxidation. This study indicates a high potential for the formation of Mn oxides at locations in a drinking water distribution system or in premise plumbing where both Mn(II) and Cu(II) are available. It provides insights into the co-occurrence of other metals with Mn deposits that is frequently observed in distribution systems.