105 research outputs found
CATALYTIC HYDROLYSIS OF DICLOFOP-METHYL ON CA-MONTMORILLONITES, NA-MONTMORILLONITES AND K-MONTMORILLONITES
No full textDirect and indirect photolysis of two quinolinecarboxylic herbicides in aqueous systems
No full textThe photodegradation of two quinolinecarboxylic herbicides, 7-chloro-3-methylquinoline-8-carboxylic
acid (QMe) and 3,7-dichloroquinoline-8-carboxylic acid (QCl), was studied in aqueous solution at different
irradiation wavelengths. The effect of sunlight irradiation was investigated also in the presence of
titanium dioxide (TiO2). UV irradiation degraded rapidly QMe affording 7-chloro-3-methylquinoline
(MeQ) through a decarboxylation reaction. The reaction rate was lower in the presence of dissolved
organic carbon (DOC) because of the adsorption of the herbicide on the organic components. Instead,
QCl was stable under both UV light and sunlight irradiation. The irradiation of QMe or QCl solutions with
simulated sunlight in the presence of TiO2 produced the complete mineralization of the two herbicides
Direct and indirect photolysis of cyhalofop in aqueous systems
No full textThe photodegradation of the aryloxyphenoxy propionic herbicide cyhalofop-butyl (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]butylpropanoate (CyB), and of its primary metabolite (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid (CyA) was studied in water at different irradiation wavelengths. The sunlight irradiation was investigated also in the presence of humic acid (HA), Fe oxide, titanium dioxide (TiO2) and zinc oxide (ZnO) as photocatalysts.
CyB and CyA were rapidly degraded by UV irradiation. CyB afforded the butyl ester of 2-[3-(4-cyano-2-fluorophenyl)-4-hydroxy-phenoxy]propanoic acid (CyI), a metabolite arising from a photo-Fries rearrangement. Instead, CyA yielded (R)-2-4-(4-carboxyl-2-fluorophenoxy)phenoxypropanoic acid (CyD), a dicarboxylic acid arising from the photo-hydrolysis of cyano group via amide. CyB was stable in simulated sunlight also in the presence of the catalysts tested.
The irradiation of a CyA solution, in the presence of HA or Fe oxide, with simulated sunlight did not produce any significant degradation. In the same experimental conditions, CyA was totally mineralized in the presence of TiO2 and ZnO
HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF THE HERBICIDE IMAZAPYR RESIDUES IN WATER AND SOIL
No full textA rapid method for determining residues of the herbicide imazapyr in water and soil is described. The soil samples were extracted with aqueous methanol and, after concentrating, the residue was estimated by HPLC with UV detection at 250 nm. Imazapyr dissolved in water was quantified by injecting the samples without any previous treatments. Analyses were performed without clean-up of soil and water samples. The pre-concentration of samples was required only at very low herbicide amounts. The maximum recovery was achieved by methanol/water (3:2 v/v) with both soils after three extraction procedures. The detection limits were 0.01 mg/l and 0.05 mg/kg in water and soil, respectively
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