• photocatalytic reduction of cr(vi) on nanosized fe2o3 supported on natural algerian clay: characteristics, kinetic and thermodynamic study

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    • تاریخ ارائه: 1392/01/01
    • تاریخ انتشار در تی پی بین: 1392/01/01
    • تعداد بازدید: 555
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     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 140 m2 g−1. the photo-electrochemical characterization is undertaken to assess the photoactivity. the sensitizer fe2o3 has a conduction band (−0.76 vsce) more cathodic than the chromate level (∼0.1 vsce). 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 3 h for a concentration of 50 ppm at ph ∼ 2 with a dosage of 1 mg/ml. the chromate removal obeys to a pseudo first order kinetic with an apparent constant of 0.013 min−1. the negative enthalpy and free energy indicate a spontaneous and exothermic process. upon solar irradiation, the reduction of 100 ppm cr(vi) solution is completed after only 50 min.

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