Photocatalytic reduction of Cr(VI) on nanosized Fe2O3 supported on natural Algerian clay: Characteristics, kinetic and thermodynamic study
► The work deals with the Cr(VI) reduction on Fe2O3 loaded clay under visible light. ► The conduction band of Fe2O3 (−1.08V) is more negative than the HCrO4-/Cr3+ level. ► The Fe2O3/clay hetero-system is synthesized by impregnation. ► The Cr(VI) reduction follows a pseudo first order kinetic with of...
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Published in | Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 200-202; pp. 611 - 618 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Elsevier B.V
15.08.2012
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | ► The work deals with the Cr(VI) reduction on Fe2O3 loaded clay under visible light. ► The conduction band of Fe2O3 (−1.08V) is more negative than the HCrO4-/Cr3+ level. ► The Fe2O3/clay hetero-system is synthesized by impregnation. ► The Cr(VI) reduction follows a pseudo first order kinetic with of oxalic acid.
Nanosized α-Fe2O3 (hematite) supported on Algerian clay (Fe2O3/clay), by impregnation is successfully used for the chromate reduction under visible light. The hetero-system is investigated by X-ray diffraction, FT-IR, scanning electron microscopy and energy dispersive spectroscopy (EDS) analysis. The microscopic observation shows that the supported hematite α-Fe2O3 is uniformly spread on the clay which consists mainly of ∼80% illite. The BET measurement gives a specific surface area of 140m2g−1. The photo-electrochemical characterization is undertaken to assess the photoactivity. The sensitizer Fe2O3 has a conduction band (−0.76VSCE) more cathodic than the chromate level (∼0.1VSCE). As application, the reduction is optimized with respect to catalyst dosage, Cr(VI) concentration, pH and temperature. A remarkable performance is obtained in less than 3h for a concentration of 50ppm at pH∼2 with a dosage of 1mg/mL. The chromate removal obeys to a pseudo first order kinetic with an apparent constant of 0.013min−1. The negative enthalpy and free energy indicate a spontaneous and exothermic process. Upon solar irradiation, the reduction of 100ppm Cr(VI) solution is completed after only 50min. |
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Bibliography: | http://dx.doi.org/10.1016/j.cej.2012.06.121 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 1385-8947 1873-3212 |
DOI: | 10.1016/j.cej.2012.06.121 |