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Iron oxides semiconductors are efficients for solar water disinfection: A comparison with photo-Fenton processes at neutral pH

Paper ID Volume ID Publish Year Pages File Format Full-Text
45744 46421 2015 12 PDF Available
Title
Iron oxides semiconductors are efficients for solar water disinfection: A comparison with photo-Fenton processes at neutral pH
Abstract

•For the first time iron oxides has been assessed as an efficient catalyst for solar water disinfection at neutral pH.•Iron oxides can act as semiconductor to photocatalytic bacterial inactivation.•Iron oxides are also good catalyst in heterogeneous photo-Fenton disinfection.•ROS involved in semiconducting and heterogeneous photo-Fenton process are identified.

The photocatalytic activities of four different commercially available iron (hydr)oxides semiconductors, i.e. hematite (α-Fe2O3), goethite (α-FeOOH), wüstite (FeO) and magnetite (Fe3O4), were evaluated for bacteria inactivation at neutral pH in the absence or presence of H2O2. Our results showed that heterogeneous photocatalysis and/or photo-Fenton processes catalyzed by low concentrations of reagents (0.6 mg/L Fe3+ and 10 mg/L H2O2) under sunlight may serve as a disinfection method for waterborne bacterial pathogens. In particular, we found that, with the exception of magnetite which need H2O2 as electron acceptor, all the other semiconductor iron (hydr)oxides were photoactive under sunlight in absence of H2O2 (using only oxygen as electron acceptor). Furthermore, for all iron (hydr)oxide studied in this work, no bacterial reactivation and/or growth was observed after photo-Fenton treatment. The same antimicrobial activity was obtained for the photocatalytic semiconducting action of hematite and goethite. Additionally, a delayed disinfection effect was observed to continue in the dark for the photo-assisted wüstite-based treatment. Electron spin resonance (ESR) in combination with spin-trapping was employed to detect reactive oxygen species (ROS) involved in heterogeneous photocatalysis and/or photo-Fenton treatments mediated by iron (hydr)oxide particles. In particular, ESR confirmed that OH and O2− radicals were the principal ROS produced under photo-assisted action of iron (hydr)oxide particles in the absence or presence of H2O2. We also found that the components of natural water (i.e. natural organic matter (NOM) and inorganic substances) did not interfere with the photocatalytic semiconducting action of hematite to bacterial inactivation. However, these components enhance the bacterial inactivation by heterogeneous photo-Fenton action of hematite.Overall our results demonstrated, for the first time, that low concentration of iron (hydr)oxides, acting both as photocatalytic semiconductors or catalysts of the heterogeneous photo-Fenton process at neutral pH, may provide a useful strategy for efficient bacterial disinfection.

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Keywords
Iron (hydr)oxide; Bacterial inactivation; Semiconductors; Heterogeneous photo-Fenton; Photo-Fenton at neutral pH
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 166–167, May 2015, Pages 497–508
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