Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan, 430079, PR China.
Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan, 430079, PR China.
J Hazard Mater. 2018 Feb 5;343:356-363. doi: 10.1016/j.jhazmat.2017.10.008. Epub 2017 Oct 5.
In this study, we demonstrate that Mn can greatly promote the Cr(VI) reduction by oxalic acid at pH<5 via an induction period and a subsequent auto-acceleration process. The Cr(VI) reduction rate constant during the late auto-acceleration process was about 10 times that of the initial induction period. Characterization results revealed that this interesting two-step Cr(VI) reduction phenomenon was attributed to the in-situ generated Mn by the oxidation of Mn with Cr(VI) in the presence of oxalic acid during the induction period. The in-situ generated Mn might complex with oxalate and Cr(VI) to produce a ternary complex, thus facilitating the electron transfer from oxalate to Cr(VI) to automatically accelerate the Cr(VI) reduction process. These findings shed insight into the possible roles of widely existed Mn ions (Mn and Mn) and oxalic acid in the transformation of Cr(VI) in natural aquatic environment, and also provided an efficient way to remediate Cr(VI)-containing acid wastewater.
在这项研究中，我们证明了在 pH<5 的条件下，Mn 可以通过诱导期和随后的自动加速过程极大地促进草酸对 Cr(VI)的还原。在后期自动加速过程中，Cr(VI)的还原速率常数约为初始诱导期的 10 倍。表征结果表明，这种有趣的两步 Cr(VI)还原现象归因于在诱导期内，Mn 与 Cr(VI)发生氧化反应，在存在草酸的情况下原位生成的 Mn。原位生成的 Mn 可能与草酸盐和 Cr(VI)形成三元配合物，从而促进电子从草酸盐向 Cr(VI)转移，自动加速 Cr(VI)的还原过程。这些发现深入了解了在天然水环境污染中广泛存在的 Mn 离子（Mn 和 Mn）和草酸在 Cr(VI)转化中的可能作用，也为含 Cr(VI)酸性废水的修复提供了一种有效方法。
