A novel visible light-driven TiO2 photocatalytic reduction for hexavalent chromium wastewater and mechanism
Titanium dioxide (TiO2) photocatalyst was prepared with a sol-gel method and its characterizations were analyzed TiO2 photocatalytic reduction of Cr6+ was investigated in visible light irradiation and reduction mechanisms were calculated. Prepared TiO2 is anatase with a bandgap of about 2.95 eV. Exp...
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| Autores principales: | , , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
IWA Publishing
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/51c3475ec45a4559962c850b748bac51 |
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| Sumario: | Titanium dioxide (TiO2) photocatalyst was prepared with a sol-gel method and its characterizations were analyzed TiO2 photocatalytic reduction of Cr6+ was investigated in visible light irradiation and reduction mechanisms were calculated. Prepared TiO2 is anatase with a bandgap of about 2.95 eV. Experimental results display that almost 100% of Cr6+ is removed by visible light-driven TiO2 photocatalytic reduction after 120 min when Cr2O72− initial concentration is 1.0 mg·L−1, TiO2 dosage is 1.0 g·L−1, and pH value is 3. In acidic aqueous solution, HCrO4− is the dominant existing form of Cr6+ and is adsorbed by TiO2, forming a complex catalyst HCrO4−/TiO2 with an increase in wavelength to the visible light zone, demonstrated by UV–Vis diffuse reflection spectroscopy. Based on X-ray photoelectron spectroscopy data, it can be deduced that Cr6+ is adsorbed on the surface of TiO2 and then reduced to Cr3+ in situ by photoelectrons. Self-assembly of HCrO4−/TiO2 complex catalyst and self-reduction of Cr6+ in situ are the key steps to start the visible light-driven TiO2 photocatalytic reduction. Furthermore, TiO2 photocatalytic reduction of Cr6+ fits well with pseudo-first-order kinetics and has the potential application to treat chemical industrial wastewater. HIGHLIGHTS
Cr(VI) is efficiently removed by visible light-driven TiO2 photocatalytic reduction reaction.;
Photoinduced electrons are the major reductive substance for Cr(VI) removal.;
Adsorption, reduction in situ, and desorption are involved in reduction mechanism of Cr(VI).;
Photocatalytic reduction of Cr(VI) fits well with pseudo-first-order kinetics and rate constant is calculated.; |
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