Preparation and characterization of the system NiMn2O4/TiO2 by sol–gel: application to the photodegradation of benzamide under visible light
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Benzamide is successfully degraded on the novel heterosystem NiMn2O4/TiO2 under visible light. The nanosized spinel is synthesized by the sol–gel method at ~850 °C. The X-ray diffraction pattern shows narrow peaks and the oxides are well crystallized. The Mott–Schottky plot (C−2−E) of NiMn2O4 is characteristic of p-type conductivity from which a flat-band potential of −0.20 VSCE is obtained. The energy-band diagram, built from the physicochemical characterizations, predicts the electron transfer from the conduction to dissolved oxygen via TiO2. The loading of TiO2 with NiMn2O4 enhances the photoactivity and NiMn2O4 islands achieve a colloidal photochemical heterosystem, tested successfully for the light-induced benzamide degradation. The spinel dose and benzamide concentration are optimized. Under the ideal conditions, the rate of the benzamide disappearance is controlled by high-performance liquid chromatography. A conversion of 85% is reported in aerated benzamide solution (15 ppm) in less than 2 h under artificial light. This conversion rate increases up to 94% under solar light and the oxidation obeys to a first-order kinetics with a half-life of 53 min.
KeywordsBenzamide Nanosized spinel Sol–gel Heterosystem NiMn2O4/TiO2 Photocatalytic degradation Sunlight
The authors would like to express their gratitude to the Faculty of Chemistry for financial support of this research. They are grateful to N Taibi for the TEM analysis.
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Conflict of interest
The authors declare that they have no conflict of interest.
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