Redox control and hydrogen production in sediment caps using carbon cloth electrodes.
Redox control and hydrogen production in sediment caps using carbon cloth electrodes.
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DOI：
10.1021/es101003j
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发表时间：
2010-11-01
影响因子：
11.4
通讯作者：
Gregory, Kelvin B.
中科院分区：
文献类型：
--
作者：
Sun, Mei;Yan, Fei;Zhang, Ruiling;Reible, Danny D.;Lowry, Gregory V.;Gregory, Kelvin B.
降解污染物的沉淀物帽相对于砂和吸附剂修正的沉淀物帽可以提高其容纳污染物的能力，但很少有方法可以提高沉淀物帽中污染物的降解。本研究的目的是确定，碳电极放置在沉淀物帽内，在平衡电位下是否可以产生氧化还原梯度，并为污染物的潜在降解提供电子供体。在Anacostia河（华盛顿特区）沉积物上的模拟沉积物盖层中，电化学诱导的氧化还原梯度在3天内形成，并在测试期间（~100天）保持不变。氢和氧在电极表面由水电解产生，并可作为污染物降解的电子供体和受体。研究了影响产氢的电化学和地球化学因素。产氢动力学表现为零级，库仑效率为~75%，产氢速率与2.5V ~ 5V之间的外加电位成正比，受ph的影响不大。在天然有机物存在的情况下，离子强度的增加促进了产氢。在间歇式反应器中，石墨电极刺激的四氯苯降解取决于施加的电压和氢的产生，其浓度高于生物脱氯的阈值。这些发现表明，电化学反应盖层可以潜在地用于制造能够促进盖层内污染物化学或生物转化的“活性”沉积物盖层。
Sediment caps that degrade contaminants can improve their ability to contain contaminants relative to sand and sorbent-amended caps, but few methods to enhance contaminant degradation in sediment caps are available. The objective of this study was to determine if, carbon electrodes emplaced within a sediment cap at poised potential could create a redox gradient and provide electron donor for the potential degradation of contaminants. In a simulated sediment cap overlying sediment from the Anacostia River (Washington, DC), electrochemically induced redox gradients were developed within 3 days and maintained over the period of the test (~100 days). Hydrogen and oxygen were produced by water electrolysis at the electrode surfaces and may serve as electron donor and acceptor for contaminant degradation. Electrochemical and geochemical factors that may influence hydrogen production were studied. Hydrogen production displayed zero order kinetics with ~75% coulombic efficiency and rates were proportional to the applied potential between 2.5V to 5V and not greatly affected by pH. Hydrogen production was promoted by increasing ionic strength and in the presence of natural organic matter. Graphite electrode-stimulated degradation of tetrachlorobenzene in a batch reactor was dependent on applied voltage and production of hydrogen to a concentration above the threshold for biological dechlorination. These findings suggest that electrochemical reactive capping can potentially be used to create “reactive” sediments caps capable of promoting chemical or biological transformations of contaminants within the cap.
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影响因子：
11.4
作者：
Gregory, KB;Lovley, DR
通讯作者：
Lovley, DR
影响因子：
12.8
作者：
Jacobs, PH;Förstner, U
通讯作者：
Förstner, U
影响因子：
1.8
作者：
Khaitan, Sameer;Dzombak, David A.;Lowry, Gregory V.
通讯作者：
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影响因子：
11.4
作者：
Gent, David B.;Wani, Altaf H.;Alshawabkah, Akram
通讯作者：
Alshawabkah, Akram
影响因子：
11.4
作者：
Call, Douglas;Logan, Bruce E.
通讯作者：
Logan, Bruce E.