Effect of Organic Compounds and Copper on Chromium(VI) Reduction: Electrochemical Investigation of Electron Transfer Rates
Effect of Organic Compounds and Copper on Chromium(VI) Reduction: Electrochemical Investigation of Electron Transfer Rates
复制标题
DOI：
10.1021/acsestwater.2c00309
复制
发表时间：
2022-10
期刊：
影响因子：
--
通讯作者：
N. Jemison;F. Garzon;S. Cabaniss;Peter C. Lichtner;Angelica D. Benavidez;Elijah Jessop;J. Cerrato
中科院分区：
文献类型：
--
作者：
N. Jemison;F. Garzon;S. Cabaniss;Peter C. Lichtner;Angelica D. Benavidez;Elijah Jessop;J. Cerrato
铬污染是氧化还原控制的，在环境设置中，铬以有毒和移动的铬（VI）或毒性较小的铬（III）的形式存在。Cr（VI）在不同环境条件下的还原和去除机制和动力学尚未完全了解。在这里，我们使用电化学技术在实验室控制条件下测量了铬还原的电荷转移动力学，以提供对影响铬（VI）还原的化学反应的机理见解。通过添加常见的阴离子，有机化合物，和铜，我们确定了这些成分中的每一个对Cr（VI）的还原通过伏安测量使用金旋转盘电极的影响。铜作为一个电子穿梭和促进更快的Cr（VI）还原速率。硫酸盐和氯化物以及有机柠檬酸盐吸附到电极上，减缓了Cr（VI）的还原。某些有机物（抗坏血酸盐和半胱氨酸以及较小程度的草酸盐）的氧化与Cr（VI）的还原偶联，增加了Cr（VI）的还原速率，而其他有机物（谷氨酸盐和柠檬酸盐）则没有被电化学氧化。我们在一个相对简单的Cr（VI）系统上的工作说明了如何以创新的方式应用电化学测量，以提供更直接的测量环境和地球化学反应的电子转移动力学。
Chromium contamination is redox-controlled, with Cr occurring in environmental settings as toxic and mobile Cr(VI) or less toxic Cr(III). The mechanisms and kinetics of Cr(VI) reduction and removal under variable environmental conditions are not fully understood. Here, we measure the charge transfer kinetics of Cr reduction under laboratory-controlled conditions using electrochemical techniques to provide mechanistic insights into the chemical reactions affecting the reduction of Cr(VI). By the addition of common anions, organic compounds, and copper, we determined the impact of each of these constituents on Cr(VI) reduction through voltammetric measurements using a gold rotating disk electrode. Copper acted as an electron shuttle and promoted faster Cr(VI) reduction rates. Sulfate and chloride as well as the organic citrate adsorbed to the electrode and slowed Cr(VI) reduction. The oxidation of certain organics (ascorbate and cysteine as well as oxalate to a lesser extent) was coupled to the reduction of Cr(VI), increasing the Cr(VI) reduction rate, while other organics (glutamate and citrate) were not electrochemically oxidized. Our work on a relatively simple Cr(VI) system illustrates how electrochemical measurements can be applied in an innovative way to provide a more direct measurement of the electron transfer kinetics of environmental and geochemical reactions.