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Papers by JULIANA JUDITH PEREZ GARCIA
Journal of Photochemistry and Photobiology A: …, 2003
The photocatalytic degradation of imazaquin, a herbicide of the imidazolinone class, in an aqueou... more The photocatalytic degradation of imazaquin, a herbicide of the imidazolinone class, in an aqueous suspensions of titanium dioxide as catalyst was investigated. A pseudo-first-order kinetic model was used to describe the results. The effect of sonication time, catalyst loading, initial concentration of imazaquin, hydrogen peroxide and pH, temperature and radiation source were examined. The disappearance of imazaquin and the increase of nitrate ion content as a function of irradiation time were analyzed by HPLC. The ammonium ion formation was determined spectrophotometrically at 694 nm. A lower solution pH in the 3-11 range was found to be favorable to degradation. The addition of H 2 O 2 up to 10 −3 mol l −1 enhanced the degradation rate and decreased it at higher concentrations. The photocatalytic effect was more efficient in a suspension containing 2.0 g l −1 TiO 2 with 1 h sonication in the dark rather than with 20 min sonication before irradiation. Solar radiation decomposed the herbicide faster than an artificial source. The activation energy was estimated through the variation of temperature in the range 20-40 • C.
Journal of Photochemistry and Photobiology A: …, 2003
The photocatalytic degradation of imazaquin, a herbicide of the imidazolinone class, in an aqueou... more The photocatalytic degradation of imazaquin, a herbicide of the imidazolinone class, in an aqueous suspensions of titanium dioxide as catalyst was investigated. A pseudo-first-order kinetic model was used to describe the results. The effect of sonication time, catalyst loading, initial concentration of imazaquin, hydrogen peroxide and pH, temperature and radiation source were examined. The disappearance of imazaquin and the increase of nitrate ion content as a function of irradiation time were analyzed by HPLC. The ammonium ion formation was determined spectrophotometrically at 694 nm. A lower solution pH in the 3-11 range was found to be favorable to degradation. The addition of H 2 O 2 up to 10 −3 mol l −1 enhanced the degradation rate and decreased it at higher concentrations. The photocatalytic effect was more efficient in a suspension containing 2.0 g l −1 TiO 2 with 1 h sonication in the dark rather than with 20 min sonication before irradiation. Solar radiation decomposed the herbicide faster than an artificial source. The activation energy was estimated through the variation of temperature in the range 20-40 • C.