Degradation of Gesaprim Herbicide by Heterogeneous Photocatalysis Using Fe-Doped TiO2

Noemí A Quiroz,Susana S Martínez,Cristina L Bahena,Dulce J R Gutierrez

doi:10.4236/ijg.2011.24068

Noemí A Quiroz, Susana S Martínez + Show 2 more

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https://doi.org/10.4236/ijg.2011.24068

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Abstract

Fe-doped TiO2 was prepared by the sol gel method and characterized by X-ray diffraction. All the Fe-doped TiO2 were composed of an anatase crystal form. The activity of the Fe-doped TiO2 for the degradation of the gesaprim commercial herbicide (which contains atrazine as active compound and formulating agents) was studied by varying the iron content during UV (15 W), visible light and solar irradiations. The visible light came from commercial saving energy lamps (13, 15 and 20 Watts). The gesaprim degradation rate depended on the iron content in the photo catalyst. The Fe-doped TiO2 (0.5% by weight of TiO2) showed higher TOC removal under visible light and was more active than the undoped TiO2 photo catalyst under the light irradiation sources tested. Over 90% of chemical oxygen demand abatement was achieved with both UV and visible light but less time was required to decrease the chemical oxygen demand content by using the catalyst doped with iron at 0.5% under visible light. It was observed that the degradation of gesaprim increased by increasing the iron content in the catalyst under visible light.

Highlights

Nowadays, the use of herbicides in agriculture activities to control weedy plants and to increase food production has become an important tool to the detriment of the en- vironment
The gesaprim degradation rate depended on the iron content in the photo catalyst
Over 90% of chemical oxygen demand abatement was achieved with both UV and visible light but less time was required to decrease the chemical oxygen demand content by using the catalyst doped with iron at 0.5% under visible light

Summary

Introduction

The use of herbicides in agriculture activities to control weedy plants and to increase food production has become an important tool to the detriment of the en- vironment. The herbicides and their degradation products (complex metabolites) may alter the natural habitats for different plant and animal species depending on how they are transported in the environment. The main compound of this family is the atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and it is found in the environment contaminating soil and water reserves [2] This herbicide belongs to the persistent organic pollutants because of its low biodegradability and long half-life (60 and 100 days) in water. Several processes have been developed to remove atrazine from aqueous wastes, such as activated carbon and its combination with ozone [3,4], adsorption onto carbon nanotubes [5], adsorption onto zeolites [6], adsorption on fractionated Al-pillared and Fe-Al-pillared clays [7], photochemical degradation in the presence of hydrogen peroxide and microwave [8], reverse osmosis [9], ozone [10], hydrogen peroxide with ozone [11], electro-Fenton [12], Fenton and photo-Fenton [13], photolysis by TiO2 semiconductor [14,15,16,17,18], atrazine by nanoscale zero valent iron supported on organobentonite [19], and hydrogen peroxide with TiO2, and Fe2O3 semiconductor suspensions assisted by light [20,21,22], among others

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