Fundamental Mechanisms of Lead Oxidation: Effects of Chlorine, Chloramine and Natural Organic Matter on Lead Release in Drinking Water

0504447 Korshin该提案解决了一个重要的问题，即铅向饮用水中的释放，其动机是最近在华盛顿特区观察到的铅释放大大增加。该问题归因于从游离氯化的实践转向使用氯胺化。研究人员提出了一种新的模式，管理铅释放与这一观察一致，并基于几个假设的现象：1）形成铅（IV），铅（II）的氧化不溶性形式，游离氯的可溶性形式，2）铅（IV）的还原和天然有机物的胶体动员，以及3）在铅轴承材料表面的氧电化学还原产生铅（II）。拟议的活动是实验性的，重点放在这三个方面，使用模型沃茨和各种含铅材料。工作将旨在阐明这些过程，包括其动力学。PI将使用收集的天然有机物以及NOM物质模型。表面表征也将集中在表面氧化层的识别上。

0504447 Korshin This proposal addresses an important problem, release of lead into drinking water, motivated by recent observations of greatly increased lead release in Washington D.C. The problem is attributed to a switch from the practice of free chlorination to use of chloramination. The researchers propose a new paradigm governing lead release consistent with this observation and based on several hypothesized phenomena: 1) formation of Pb(IV), an insoluble form by oxidation of Pb(II), the soluble form by free chlorine, 2) reduction of Pb(IV) and colloidal mobilization of it by natural organic matter, and 3) electrochemical reduction of oxygen at the lead bearing material surface to produce Pb(II). The proposed activity is experimental and focuses on these three aspects using model waters and a variety of lead-bearing materials. Work will be aimed at elucidating these processes including their kinetics. The PIs will use collected natural organic matter as well as model NOM substances. Surface characterization would also focus on identification of the surface oxide layers.