Degradation study of malachite green on chitosan films containing heterojunctions of melon/TiO<sub>2</sub> absorbing visible-light in solid-gas interfaces
Urea modified TiO<sub>2</sub> nanoparticles were synthesized at different TiO<sub>2</sub>: urea ratios (10, 30 and 60 (%wt) named UTiO2-10, 30 and 60) by sol-gel method and annealing at 400 °C during 1 h. Characterization revealed the presence of TiO<sub>2</sub> n...
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| Autores principales: | , , , , , |
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| Formato: | Articulo Preprint |
| Lenguaje: | Inglés |
| Publicado: |
2019
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/124478 |
| Aporte de: |
| Sumario: | Urea modified TiO<sub>2</sub> nanoparticles were synthesized at different TiO<sub>2</sub>: urea ratios (10, 30 and 60 (%wt) named UTiO2-10, 30 and 60) by sol-gel method and annealing at 400 °C during 1 h. Characterization revealed the presence of TiO<sub>2</sub> nanoparticles with visible light absorption (between 400 and 500 nm) probably due by the formation of thermolysis urea byproducts such as melon, which may induce a TiO<sub>2</sub>/melon heterojunction. Then, modified nanoparticles were immobilized on chitosan films by adding 30% (70QS/30UTiO<sub>2</sub>) and 50% 50QS/50UTiO<sub>2</sub>) of UTiO<sub>2</sub> nanoparticles. Functionalized films were characterized by SEM-EDS, DRS and AFM. Photo-induced degradation of malachite green stains was evaluated on these films under different wavelengths. Upon UV-A + visible light irradiation, films showed good activity even slightly better than those containing Evonik P-25 (70QS/30P-25). Upon visible light between 450 and 800 nm, films evidenced a satisfactory performance but slower than under UV-A + visible light irradiation whereas the photobleaching activity of 70QS/30P-25 was very poor. When visible light irradiation with wavelengths higher than 590 nm was used, a slight photobleaching was also observed. DRS spectra taken at different irradiation times showed that dye underwent N-demethylated oxidative reactions either upon UV–vis or visible light irradiation. ATR-FTIR measurements revealed the generation of benzophenones after 6 h of irradiation probably suggesting the formation of singlet oxygen under visible light. 70QS/30UTiO<sub>2</sub>-10 films showed a good photo-bleaching activity after 18 h of continuous UV-A + visible light irradiation. |
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