Performance and Mechanisms of Iron Electrocoagulation for Removal of Chromium(VI) from Drinking Water

铁电凝去除饮用水中六价铬的性能和机理

• 批准号: 1335613
• 负责人: Daniel Giammar
• 金额: $ 33万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335613&HistoricalAwards=false
• 关键词: Performance; Mechanisms; Iron; Electrocoagulation; Removal

CBET-1335613Daniel GiammarWashington University in St. LouisChromium(VI) is a toxic contaminant that has been observed in private and public water supplies as well as in treated drinking water. Current drinking water standards are only applicable to total chromium, which can be present as chromium(VI) as well as the much less toxic form of chromium(III) that is even a nutrient at low concentrations. It is likely that new drinking water standards specific to chromium(VI) will be implemented, and iron electrocoagulation is a technology with the potential to achieve the low concentrations that may be required. In iron electrocoagulation a direct current is applied between two iron electrodes. One of the electrodes is oxidized to release iron(II) to solution, and this soluble iron(II) can directly reduce chromium(VI) or be oxidized to iron(III) to produce iron oxide solids on which chromium(VI) can be reduced and adsorbed. Iron electrocoagulation for chromium(VI) removal has multiple removal pathways that involve homogeneous and heterogeneous chemical reduction, adsorption, and co-precipitation. The primary objective of this research project is to advance the mechanistic understanding of chromium(VI) removal by iron electrocoagulation. The project will evaluate electrocoagulation performance over a broad range of water chemistry conditions in a laboratory-scale electrocoagulation reactor. Analytical methods will track changes in both total dissolved chromium and chromium(VI) to the very low levels that are being considered for regulations. The investigation will use advanced spectroscopic and stable isotope tools to identify the dominant reaction mechanisms occurring in the electrocoagulation reactor. X-ray absorption spectroscopy, which will be performed at national user facilities, will provide insights into the oxidation state and molecular-scale coordination of chromium associated with the solids generated in the reactor. Stable isotope fractionation of chromium can be diagnostic of specific reaction mechanisms. A mathematical model for electrocoagulation performance will integrate the mechanistic insights and data from the laboratory-scale experiments to enable predictions of performance over a broad range of conditions. The research will enable the optimal design of treatment strategies and accurate prediction of treatment performance for chromium(VI) removal.This project will provide scientific information that will help improve the removal of hexavalent chromium, a contaminant of critical national interest, from drinking water. The research will determine the influence of water chemistry on the reactions involved in the process, which will enable the design of effective strategies for chromium(VI) removal for a broad range of drinking water sources. The research activities will determine reaction mechanisms of interest in environmental engineering as well as earth science and materials science. The project's overall application of spectroscopic characterization and stable isotope tools will advance the overall infrastructure for environmental engineering research. The educational and outreach components of the project will enhance graduate and undergraduate teaching and promote early student interest in science and engineering.

CBET-1335613Daniel Giammarwashington大学位于圣路易斯龙（VI）是一种有毒的污染物，在私人和公共供水以及处理过的饮用水中都可以观察到。 当前的饮用水标准仅适用于总铬，可以作为铬（VI）以及毒性较小的铬（III）的毒性较小，甚至在低浓度下是一种营养素。 可能会实施特定于铬（VI）的新饮用水标准，铁电凝是一项技术，有可能达到可能需要的低浓度。 在铁电凝中，在两个铁电极之间施加直流电流。 将其中一个电极氧化以将铁（II）释放到溶液中，并且该可溶性铁（II）可以直接减少铬（VI）或氧化为铁（III），以产生可以减少铬（VI）的氧化铁固体（III）。 用于铬（VI）去除的铁电凝具有多个去除途径，涉及均质和异质化学还原，吸附和共沉淀。 该研究项目的主要目的是通过铁电凝促进对铬（VI）去除的机械理解。 该项目将在实验室尺度电凝反应器中评估在广泛的水化学条件下电凝性的性能。 分析方法将跟踪总溶解的铬和铬（VI）的变化，以确定法规所考虑的非常低的水平。 该研究将使用晚期光谱和稳定的同位素工具来识别电凝反应器中发生的主要反应机制。 X射线吸收光谱将在国家用户设施上进行，将提供有关与反应器中产生的固体相关的铬的氧化状态和分子规范协调的见解。 铬的稳定同位素分馏可以是特定反应机制的诊断。 电凝性能的数学模型将整合实验室规模实验的机械见解和数据，以在广泛的条件下对性能进行预测。 这项研究将使治疗策略的最佳设计以及对铬（VI）去除的治疗绩效的准确预测。该项目将提供科学信息，以帮助改善去除六价铬的硫磺铬，这是对饮酒水的关键国家利益的污染物。 该研究将确定水化学对过程中涉及的反应的影响，这将使铬（VI）去除有效策略（VI）的各种饮用水源。 研究活动将确定环境工程以及地球科学和材料科学感兴趣的反应机制。 该项目的光谱表征和稳定的同位素工具的总体应用将推动环境工程研究的整体基础架构。 该项目的教育和外展成分将增强研究生和本科教学，并促进学生对科学和工程学的早期兴趣。