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Degradation of glyphosate in soil photocatalyzed by Fe3O4/SiO2/TiO2 under solar light.

Xu X, Ji F, Fan Z, He L - Int J Environ Res Public Health (2011)

Bottom Line: Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2).The thinner the soil is, the better the glyphosate degradation is.Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2).

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China. xuxuan@cqu.edu.cn

ABSTRACT
In this study, Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst was prepared via a sol-gel method, and Fe(3)O(4) particles were used as the core of the colloid. Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2). FTIR characterization shows that diffraction peaks of Ti-O-Si chemical bonds become obvious when the Fe(3)O(4) loading is more than 0.5%. SEM characterization indicates that agglomeration occurs in the Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst, whereas photocatalysts modified by Fe(3)O(4)/SiO(2) present excellent visible light absorption performance and photocatalytic activity, especially when the Fe(3)O(4) loading is 0.5%. Photocatalytic degradation of glyphosate in soil by these photocatalysts under solar irradiation was investigated. Results show that 0.5% Fe(3)O(4)/SiO(2)/TiO(2) has the best photocatalytic activity. The best moisture content of soil is 30%~50%. Degradation efficiency of glyphosate reaches 89% in 2 h when the dosage of photocatalyst is 0.4 g/100 g (soil), and it increased slowly when more photocatalyst was used. Soil thickness is a very important factor for the photocatalytic rate. The thinner the soil is, the better the glyphosate degradation is. Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2).

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XRD spectra of photocatalysts: (a) TiO2; (b) 0.1%Fe3O4/SiO2/TiO2; (c) 0.25%Fe3O4/SiO2/TiO2; (d) 0.5%Fe3O4/SiO2/TiO2; (e) 1%Fe3O4/SiO2/TiO2; (f) 5%Fe3O4/SiO2/TiO2; (g) 10%Fe3O4/SiO2/TiO2.
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f1-ijerph-08-01258: XRD spectra of photocatalysts: (a) TiO2; (b) 0.1%Fe3O4/SiO2/TiO2; (c) 0.25%Fe3O4/SiO2/TiO2; (d) 0.5%Fe3O4/SiO2/TiO2; (e) 1%Fe3O4/SiO2/TiO2; (f) 5%Fe3O4/SiO2/TiO2; (g) 10%Fe3O4/SiO2/TiO2.

Mentions: The XRD patterns of photocatalysts are compared in Figure 1. Only the diffraction peaks of typical anatase TiO2 were observed with 2θ at 25.3°, 37.9°, 48.2°, 54.0°, 55.1°, 62.6°, 68.8°, 70.3°and 75.2°. Diffraction peaks of titanate and Fe3O4 crystal didn’t appear. This indicates that the Fe3O4 is well encapsulated by SiO2, and no interaction between Fe3O4 and TiO2 occurs.


Degradation of glyphosate in soil photocatalyzed by Fe3O4/SiO2/TiO2 under solar light.

Xu X, Ji F, Fan Z, He L - Int J Environ Res Public Health (2011)

XRD spectra of photocatalysts: (a) TiO2; (b) 0.1%Fe3O4/SiO2/TiO2; (c) 0.25%Fe3O4/SiO2/TiO2; (d) 0.5%Fe3O4/SiO2/TiO2; (e) 1%Fe3O4/SiO2/TiO2; (f) 5%Fe3O4/SiO2/TiO2; (g) 10%Fe3O4/SiO2/TiO2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3118888&req=5

f1-ijerph-08-01258: XRD spectra of photocatalysts: (a) TiO2; (b) 0.1%Fe3O4/SiO2/TiO2; (c) 0.25%Fe3O4/SiO2/TiO2; (d) 0.5%Fe3O4/SiO2/TiO2; (e) 1%Fe3O4/SiO2/TiO2; (f) 5%Fe3O4/SiO2/TiO2; (g) 10%Fe3O4/SiO2/TiO2.
Mentions: The XRD patterns of photocatalysts are compared in Figure 1. Only the diffraction peaks of typical anatase TiO2 were observed with 2θ at 25.3°, 37.9°, 48.2°, 54.0°, 55.1°, 62.6°, 68.8°, 70.3°and 75.2°. Diffraction peaks of titanate and Fe3O4 crystal didn’t appear. This indicates that the Fe3O4 is well encapsulated by SiO2, and no interaction between Fe3O4 and TiO2 occurs.

Bottom Line: Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2).The thinner the soil is, the better the glyphosate degradation is.Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2).

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China. xuxuan@cqu.edu.cn

ABSTRACT
In this study, Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst was prepared via a sol-gel method, and Fe(3)O(4) particles were used as the core of the colloid. Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2). FTIR characterization shows that diffraction peaks of Ti-O-Si chemical bonds become obvious when the Fe(3)O(4) loading is more than 0.5%. SEM characterization indicates that agglomeration occurs in the Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst, whereas photocatalysts modified by Fe(3)O(4)/SiO(2) present excellent visible light absorption performance and photocatalytic activity, especially when the Fe(3)O(4) loading is 0.5%. Photocatalytic degradation of glyphosate in soil by these photocatalysts under solar irradiation was investigated. Results show that 0.5% Fe(3)O(4)/SiO(2)/TiO(2) has the best photocatalytic activity. The best moisture content of soil is 30%~50%. Degradation efficiency of glyphosate reaches 89% in 2 h when the dosage of photocatalyst is 0.4 g/100 g (soil), and it increased slowly when more photocatalyst was used. Soil thickness is a very important factor for the photocatalytic rate. The thinner the soil is, the better the glyphosate degradation is. Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2).

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