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Chlorophenol degradation using a one-pot reduction–oxidation process

Paper ID Volume ID Publish Year Pages File Format Full-Text
46839 46450 2011 8 PDF Available
Title
Chlorophenol degradation using a one-pot reduction–oxidation process
Abstract

Chlorophenol degradation was achieved using a combination of hydrodechlorination and heterogeneous Fenton-like oxidation. The process was conducted at ambient conditions (25 ± 2 °C, atmospheric pressure) as a one-pot reaction involving formic acid as H2 source for both hydrodechlorination of chlorophenols and H2O2 formation. An alumina-supported Pd–Fe catalyst was applied, which is able to decompose formic acid at the Pd sites, forming H2 and CO2, and additionally H2O2 in the presence of O2. At the same time, due to presence of iron sites on the catalyst, the H2O2 formed can be utilized for a Fenton-like oxidation reaction. Three different reaction protocols were tested, including: (i) consecutive reduction–oxidation with an initial oxygen-free phase adjusted by He purging (CRO–He), (ii) consecutive reduction–oxidation with initially oxygen-limited conditions (CRO) and (iii) simultaneous reduction–oxidation where O2 flowing was started at the beginning of the reaction (SRO). 2,4-Dichlorophenol (DCP) and pentachlorophenol (PCP) were selected as representatives for the group of chlorophenols. For DCP degradation, CRO–He and SRO showed similar efficiencies with respect to the mineralization degree (up to 70%), whereas SRO achieved a better detoxification as observed in bioluminescence tests. The CRO–He reaction over the catalyst used showed only a small decrease in its activity during the oxidation stage, with no further change after the catalyst had been recovered twice. For PCP degradation, a self-inhibition effect was observed for the SRO process, indicating that PCP is hardly degradable by catalytic oxidation. In this case, the CRO–He process, which was facilitated by initial transformation of PCP into phenol and its subsequent oxidation, clearly produced a cleaner medium. This was also confirmed by the results of the toxicity measurements. The catalyst indicated a promising stability based upon the Pd and Fe leaching results measured at the end of each run.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Chlorophenol degradation performed using a combination of reduction and oxidation. ► Better DCP degradation obtained using simultaneous reduction–oxidation. ► Consecutive reduction–oxidation process showed better PCP degradation. ► Promising stability of the Pd–Fe catalyst based on the Pd and Fe leaching results.

Keywords
Chlorophenol; Hydrodechlorination; Fenton-like; Pd–Fe catalyst; Formic acid
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 104, Issues 1–2, 27 April 2011, Pages 161–168
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