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Preparation of multifunctional gas-diffusion electrode and its application to the degrading of chlorinated phenols by electrochemical reducing and oxidizing processes

Paper ID Volume ID Publish Year Pages File Format Full-Text
46098 46429 2012 8 PDF Available
Title
Preparation of multifunctional gas-diffusion electrode and its application to the degrading of chlorinated phenols by electrochemical reducing and oxidizing processes
Abstract

Multifunctional gas-diffusion electrode with electrochemical reduction and oxidation properties was achieved based on the palladium-modified activated carbon (Pd/C). Pd/C catalysts were prepared using the formaldehyde reduction from nitric acid treated activated carbon and fully characterized by Boehm titration method, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and cyclic voltammetry (CV) techniques. The electrochemical degradation of three typical chlorinated phenols (4-chlorophenol, 2,4-dichlorophenol and pentachlorophenol) was investigated in a diaphragm electrolysis system with the Pd/C gas-diffusion electrode as a cathode, feeding firstly with hydrogen gas and then with air. The electrolysis system with 15% mass fraction nitric acid pretreated activated carbon showed better electrocatalytic activity compared to those from other mass fractions nitric acid, due to the active organic function groups increased on the surface of the activated carbon. When the ratio of Pd/C was low, Pd particles with an average size of 3.5 nm were highly dispersed in the activated carbon with an amorphous structure. The Pd/C gas-diffusion cathode cannot only reductively dechlorinate chlorinated phenols by feeding hydrogen gas, but also accelerate the two-electron reduction of O2 to H2O2 by feeding air. Therefore, the removal efficiency of chlorinated phenols reached almost 100%, conforming to the sequence of 4-chlorophenol, 2,4-dichlorophenol and pentachlorophenol. The dechlorination of three chlorinated phenols exceeded 80% after 100 min. For H2O2 and HO existed in the catholyte, the mineralization of organic pollutants in the cathodic compartment was better than that in the anodic compartment. Finally, chlorinated organic pollutants were efficiently degraded by the combined processes of reduction and oxidation in the present system.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pd/C gas-diffusion cathode exhibits high electrocatalytic dechlorination activity. ► Pd particle is main active species for electrochemical degradation of chlorophenols. ► HNO3 pretreatments of AC show great effects on catalytic properties of Pd/C. ► Chlorophenols degradation performed under a combination process of reduction and oxidation.

Keywords
Chlorinated organic pollutants; Palladium-modified electrode; Reduction and oxidation processes; Reductive dechlorination
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Preparation of multifunctional gas-diffusion electrode and its application to the degrading of chlorinated phenols by electrochemical reducing and oxidizing processes
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 125, 21 August 2012, Pages 449–456
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us