Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye
A global freshwater pollution catastrophe is looming due to pollutants of emerging concern (PECs). Conventional water treatment methods are limited in removing PECs such as pharmaceuticals and dye house effluent from aquatic systems. This study provides an effective potential solution by developing...
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MDPI AG
2022-12-01
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| author | Sabastian Simbarashe Mukonza Nhamo Chaukura Ajay Kumar Mishra |
| author_facet | Sabastian Simbarashe Mukonza Nhamo Chaukura Ajay Kumar Mishra |
| author_sort | Sabastian Simbarashe Mukonza |
| collection | DOAJ |
| description | A global freshwater pollution catastrophe is looming due to pollutants of emerging concern (PECs). Conventional water treatment methods are limited in removing PECs such as pharmaceuticals and dye house effluent from aquatic systems. This study provides an effective potential solution by developing an innovative wastewater treatment method based on solar-light-responsive semiconductor-based photocatalysts. A sol-gel synthesis technique was used to produce Fluorine-Sm<sup>3+</sup> co-doped TiO<sub>2</sub> (0.6% Sm<sup>3+</sup>) (FST3) photocatalysts. This was followed by loading multi-walled carbon nanotubes (MWCNTs) in the range of 0.25 to 1 wt% into the FST3 matrix. Solid state UV-visible spectroscopy measurements showed a bathochromic shift into the visible light region after the co-doping of TiO<sub>2</sub>, whereas XRD analysis confirmed the presence of predominantly anatase polymorphs of TiO<sub>2</sub>. The FT-IR and EDX results confirmed the presence of the F and Sm<sup>3+</sup> dopants in the synthesised photocatalysts. XRD and TEM measurements confirmed that the crystallite sizes of all synthesised photocatalysts ranged from 12–19 nm. The resultant photocatalysts were evaluated for photocatalytic degradation of Brilliant Black BN bis-azo dye in aqueous solution under simulated solar irradiation. FST3 completely degraded the dye after 3 h, with a high apparent rate constant (<i>K<sub>a</sub></i>) value (2.73 × 10<sup>−2</sup> min<sup>−1</sup>). The degree of mineralisation was evaluated using the total organic carbon (TOC) technique, which revealed high TOC removal (82%) after 3 h and complete TOC removal after 4 h. The incorporation of F improved the optical properties and the surface chemistry of TiO<sub>2</sub>, whereas Sm<sup>3+</sup> improved the quantum efficiency and the optical properties. These synergistic effects led to significantly improved photocatalytic efficiency. Furthermore, incorporating MWCNTs into the F and Sm<sup>3+</sup> co-doped TiO<sub>2</sub> (0.6% Sm<sup>3+</sup>) improved the reaction kinetics of the FST3, effectively reducing the reaction time by over 30%. Recyclability studies showed that after 5 cycles of use, the FST3/C1 degradation efficiency dropped by 7.1%, whereas TiO<sub>2</sub> degradation efficiency dropped by 33.4% after the same number of cycles. Overall, this work demonstrates a sustainable and efficient dye-removal technique. |
| first_indexed | 2024-03-09T13:15:34Z |
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| last_indexed | 2024-03-09T13:15:34Z |
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| spelling | doaj.art-7cf7992b422041b788431068cc87986a2023-11-30T21:37:01ZengMDPI AGCatalysts2073-43442022-12-011318610.3390/catal13010086Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo DyeSabastian Simbarashe Mukonza0Nhamo Chaukura1Ajay Kumar Mishra2Department of Civil Engineering, National Pingtung University of Science & Technology, Pingtung 91201, TaiwanDepartment of Physical and Earth Sciences, Sol Plaatje University, Kimberley 8301, South AfricaCollege of Medicine and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, ChinaA global freshwater pollution catastrophe is looming due to pollutants of emerging concern (PECs). Conventional water treatment methods are limited in removing PECs such as pharmaceuticals and dye house effluent from aquatic systems. This study provides an effective potential solution by developing an innovative wastewater treatment method based on solar-light-responsive semiconductor-based photocatalysts. A sol-gel synthesis technique was used to produce Fluorine-Sm<sup>3+</sup> co-doped TiO<sub>2</sub> (0.6% Sm<sup>3+</sup>) (FST3) photocatalysts. This was followed by loading multi-walled carbon nanotubes (MWCNTs) in the range of 0.25 to 1 wt% into the FST3 matrix. Solid state UV-visible spectroscopy measurements showed a bathochromic shift into the visible light region after the co-doping of TiO<sub>2</sub>, whereas XRD analysis confirmed the presence of predominantly anatase polymorphs of TiO<sub>2</sub>. The FT-IR and EDX results confirmed the presence of the F and Sm<sup>3+</sup> dopants in the synthesised photocatalysts. XRD and TEM measurements confirmed that the crystallite sizes of all synthesised photocatalysts ranged from 12–19 nm. The resultant photocatalysts were evaluated for photocatalytic degradation of Brilliant Black BN bis-azo dye in aqueous solution under simulated solar irradiation. FST3 completely degraded the dye after 3 h, with a high apparent rate constant (<i>K<sub>a</sub></i>) value (2.73 × 10<sup>−2</sup> min<sup>−1</sup>). The degree of mineralisation was evaluated using the total organic carbon (TOC) technique, which revealed high TOC removal (82%) after 3 h and complete TOC removal after 4 h. The incorporation of F improved the optical properties and the surface chemistry of TiO<sub>2</sub>, whereas Sm<sup>3+</sup> improved the quantum efficiency and the optical properties. These synergistic effects led to significantly improved photocatalytic efficiency. Furthermore, incorporating MWCNTs into the F and Sm<sup>3+</sup> co-doped TiO<sub>2</sub> (0.6% Sm<sup>3+</sup>) improved the reaction kinetics of the FST3, effectively reducing the reaction time by over 30%. Recyclability studies showed that after 5 cycles of use, the FST3/C1 degradation efficiency dropped by 7.1%, whereas TiO<sub>2</sub> degradation efficiency dropped by 33.4% after the same number of cycles. Overall, this work demonstrates a sustainable and efficient dye-removal technique.https://www.mdpi.com/2073-4344/13/1/86bis-azo dyephotocatalysisphoto-mineralisationsynergistic effectsTiO<sub>2</sub> |
| spellingShingle | Sabastian Simbarashe Mukonza Nhamo Chaukura Ajay Kumar Mishra Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye Catalysts bis-azo dye photocatalysis photo-mineralisation synergistic effects TiO<sub>2</sub> |
| title | Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye |
| title_full | Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye |
| title_fullStr | Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye |
| title_full_unstemmed | Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye |
| title_short | Photocatalytic Activity and Reusability of F, Sm<sup>3+</sup> Co-Doped TiO<sub>2</sub>/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye |
| title_sort | photocatalytic activity and reusability of f sm sup 3 sup co doped tio sub 2 sub mwcnts hybrid heterostructure for efficient photocatalytic degradation of brilliant black bis azo dye |
| topic | bis-azo dye photocatalysis photo-mineralisation synergistic effects TiO<sub>2</sub> |
| url | https://www.mdpi.com/2073-4344/13/1/86 |
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