Effect of applied voltage, initial concentration, and natural organic matter on sequential reduction/oxidation of nitrobenzene by graphite electrodes.
Effect of applied voltage, initial concentration, and natural organic matter on sequential reduction/oxidation of nitrobenzene by graphite electrodes.
复制标题
DOI：
10.1021/es300048y
复制
发表时间：
2012-06-05
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;Reible, Danny D.;Lowry, Gregory V.;Gregory, Kelvin B.
建议在反应性沉积物盖中使用碳电极，以便就地处理污染物。电极在阴极产生还原条件和H2，在阳极产生氧化条件和O2。电极垂直于渗流放置，为污染物的连续还原和氧化提供了机会。以硝基苯（NB）为探针化合物，采用电化学还原-氧化法对NB进行降解，考察了外加电压、初始浓度和天然有机物对降解速率的影响。在石墨电极和缓冲溶液的H电池反应器中，以亚硝基苯（NSB）为中间体，NB在阴极按化学计量还原为苯胺（AN）。然后在阳极处除去AN，比还原步骤更快。在体系中没有检测到常见的AN氧化中间体。NB（kNB）和NSB（kNSB）的一级还原速率常数在2 V ~ 3.5V范围内随外加电压的增加而增加（当NB初始浓度为100 μM时，2 V时kNB=0.3 d−1和kNSB=0.04 d− 1; 3.5V时kNB=1.6 d−1和kNSB=0.64 d− 1），但超过3.5V后停止增加。当NB的初始浓度从100 μ M降低到5 μM时，kNB和kNSB的降解速度分别提高了9倍和5倍，这表明对电极表面活性位点的竞争是NB降解的一个重要因素。天然有机物的存在下（无论是腐殖酸或Anacostia河沉积物孔隙水的形式）减少kNB，而略有增加kNSB，但只有在有限的程度上（~ 3倍）的溶解有机碳含量高达100毫克/升。这些研究结果表明，基于电极的反应沉积物盖帽通过顺序还原/氧化是一个潜在的强大的和可调的技术，在原位污染物降解。
Carbon electrodes are proposed in reactive sediment caps for in situ treatment of contaminants. The electrodes produce reducing conditions and H2 at the cathode and oxidizing conditions and O2 at the anode. Emplaced perpendicular to seepage flow, the electrodes provide the opportunity for sequential reduction and oxidation of contaminants. The objectives of this study are to demonstrate degradation of nitrobenzene (NB) as a probe compound for sequential electrochemical reduction and oxidation, and to determine the effect of applied voltage, initial concentration and natural organic matter on the degradation rate. In H-cell reactors with graphite electrodes and buffer solution, NB was reduced stoichiometrically to aniline (AN) at the cathode with nitrosobenzene (NSB) as the intermediate. AN was then removed at the anode, faster than the reduction step. No common AN oxidation intermediate was detected in the system. Both the first order reduction rate constants of NB (kNB) and NSB (kNSB) increased with applied voltage between 2V and 3.5 V (when the initial NB concentration was 100 µM, kNB=0.3 d−1 and kNSB=0.04 d−1at 2V; kNB=1.6 d−1 and kNSB=0.64 d−1at 3.5 V) but stopped increasing beyond the threshold of 3.5V. When initial NB concentration decreased from 100 to 5 µM, kNB and kNSB became 9 and 5 times faster, respectively, suggesting that competition for active sites on the electrode surface is an important factor in NB degradation. Presence of natural organic matter (in forms of either humic acid or Anacostia River sediment porewater) decreased kNB while slightly increased kNSB, but only to a limited extent (~factor of 3) for dissolved organic carbon content up to 100 mg/l. These findings suggest that electrode-based reactive sediment capping via sequential reduction/oxidation is a potentially robust and tunable technology for in situ contaminants degradation.
登录
查看更多内容
影响因子：
11.4
作者：
Gregory, KB;Lovley, DR
通讯作者：
Lovley, DR
影响因子：
11.4
作者：
Lohner, Svenja T.;Becker, Dirk;Tiehm, Andreas
通讯作者：
Tiehm, Andreas
影响因子：
12.8
作者：
Jacobs, PH;Förstner, U
通讯作者：
Förstner, U
影响因子：
11.4
作者：
CHIOU, CT;KILE, DE;MACCARTHY, P
通讯作者：
MACCARTHY, P
影响因子：
11.4
作者：
Aulenta, Federico;Tocca, Lorenzo;Majone, Mauro
通讯作者：
Majone, Mauro