Electrocatalytic reductive dehalogenation of polyhalogenated phenols in aqueous solution on Ag electrodes

Xu, Yongfu; Zhu, Yuelin; Zhao, Fei; Ma, Chao

doi:10.1016/j.apcata.2007.02.049

Cited by 43 publications

(24 citation statements)

References 9 publications

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“…In some cases, using larger electrode surface area is sufficient in increasing the rate of hydrogen formation [40]. Noble metals (e.g., Ag, Pt and Pd) are often used as working electrodes [41–43] because of the capability of absorbing hydrogen which promotes HDC [44]. Various materials, such as activated carbon fiber/cloth/felt, reticulated vitreous carbon and carbon nanotubes, meshed Ti, Ti/TiO 2 nanotubes, foam Ni, foam Fe and Ebonex® were frequently used as cathode substrates supporting Pd catalyst because of the penetrability and advantage for mass transfer in the dechlorination process [44–49].…”

Section: Introductionmentioning

confidence: 99%

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Rajić

Fallahpour

2015

Applied Catalysis B: Environmental

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The electrode sequence in a mixed flow-through electrochemical cell is evaluated to improve the hydrodechlorination (HDC) of trichloroethylene (TCE) in aqueous solutions. In a mixed (undivided) electrochemical cell, oxygen generated at the anode competes with the transformation of target contaminants at the cathode. In this study, we evaluate the effect of placing the anode downstream from the cathode and using multiple electrodes to promote TCE reduction. Experiments with a cathode followed by an anode (C→A) and an anode followed by a cathode (A→C) were conducted using mixed metal oxide (MMO) and iron as electrode materials. The TCE removal rates when the anode is placed downstream of the cathode (C→A) were 54% by MMO→MMO, 64% by MMO→Fe and 87% by Fe→MMO sequence. Removal rates when the anode is placed upstream of the cathode (A→C) were 38% by MMO→MMO, 58% by Fe→MMO and 69% by MMO→Fe sequence. Placing the anode downstream of the cathode positively improves (by 26%) the degradation of aqueous TCE in a mixed flow-through cell as it minimizes the influence of oxygen generated at the MMO anode on TCE reduction at the cathode. Furthermore, placing the MMO anode downstream of the cathode neutralizes pH and redox potential of the treated solution. Higher flow velocity under the C→A setup increases TCE mass flux reduction rate. Using multiple cathodes and an iron foam cathode up stream of the anode increase the removal rate by 1.6 and 2.4 times, respectively. More than 99% of TCE was removed in the presence of Pd catalyst on carbon and as an iron foam coating. Enhanced reaction rates found in this study imply that a mixed flow-through electrochemical cell with multiple cathodes up stream of an anode is an effective method to promote the reduction of TCE in groundwater.

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Section: Introductionmentioning

confidence: 99%

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Rajić

Fallahpour

2015

Applied Catalysis B: Environmental

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“…Although the nanoparticles in our initial components are absent here, prior to the growth of desired carbon nanotube encapsulated nanorods and nanoparticles, the thin oxide films, which formed during the heat-treatment of the nickel wire under ambient, would be reduced by the carbon source (oil) and a loosely metallic films would be created on the surface of the wire. The metallic films originated from the oxide films probably possess coarse surface and some raised island-like particles according to a recent publication [23] . Since the thin metallic films and the small islands are reduced from the oxide films on the surface of the bulk material, and the formed surface metallic films are probably with a loose construction, the original interface between oxide and the metal bulk would still exist and transform into the interface between the thin metallic films and small islands and the bulk material.…”

Section: Discussionmentioning

confidence: 94%

Growth of carbon encapsulated long nickel nanorods on bulk nickel substrate

Xiao-bei

Chen

Xue

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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Carbon nanotube encapsulated nickel nanorods were catalytic grown via pyrolysis of oil on a bulk nickel wire substrate. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy were employed to characterize the as-prepared sample. The results show that, carbon nanotubes possess several microns in length, the filled metallic nickel nanorods with a uniform diameter of 35 nm were tightly encapsulated by the carbon capsules. The detailed formation mechanism for the carbon nanotubes encapsulated nickel nanorods were discussed briefly.

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“…Good catalytic activity of noble metals (e.g., Ag, Pt and Pd) arises from the fact that the free energy of hydrogen adsorption is close to zero (Zheng et al, 2015). It has been demonstrated that noble metals can be effectively used for the reductive de-chlorination of chlorinated hydrocarbons when used as working electrodes, and as coatings on different electrode materials (Sonoyama and Sakata, 1999; Hoshi et al, 2004; Xu et al, 2007; Scialdone et al, 2008; Rondinini and Vertova, 2010; Scialdone et al, 2010b). …”

Section: Introductionmentioning

confidence: 99%

The influence of cathode material on electrochemical degradation of trichloroethylene in aqueous solution

et al. 2016

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In this study, different cathode materials were evaluated for electrochemical degradation of aqueous phase trichloroethylene (TCE). A cathode followed by an anode electrode sequence was used to support reduction of TCE at the cathode via hydrodechlorination (HDC). The performance of iron (Fe), copper (Cu), nickel (Ni), aluminum (Al) and carbon (C) foam cathodes was evaluated. We tested commercially available foam materials, which provide important electrode surface are and properties for field application of the technology. Ni foam cathode produced the highest TCE removal (68.4%) due to its high electrocatalytic activity for hydrogen generation and promotion of HDC. Different performances of the cathode materials originate from differences in the bond strength between atomic hydrogen and the material. With a higher electrocatalytic activity than Ni, Pd catalyst (used as cathode coating) increased TCE removal from 43.5% to 99.8% for Fe, from 56.2% to 79.6% for Cu, from 68.4% to 78.4% for Ni, from 42.0% to 63.6% for Al and from 64.9% to 86.2% for C cathodes. The performance of the palladized Fe foam cathode was tested for degradation of TCE in the presence of nitrates, as another commonly found groundwater species. TCE removal decreased from 99% to 41.2% in presence of 100 mg L−1 of nitrates due to the competition with TCE for HDC at the cathode. The results indicate that the cathode material affects TCE removal rate while the Pd catalyst significantly enhances cathode activity to degrade TCE via HDC.

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Electrocatalytic reductive dehalogenation of polyhalogenated phenols in aqueous solution on Ag electrodes

Cited by 43 publications

References 9 publications

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Growth of carbon encapsulated long nickel nanorods on bulk nickel substrate

The influence of cathode material on electrochemical degradation of trichloroethylene in aqueous solution

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