The treatment of pesticides is a necessity in view of the stability and toxicity of the pesticides that generate them. The objective of this work is to study the degradation of picloram in aqueous medium under UV irradiation. It is a selective and systemic herbicide that can control woody plants and broadleaf weeds. The irradiations were carried out using a mercury vapor lamp of wavelength λ = 365 nm. A high performance liquid chromatograph equipped with a UV / visible detector was used to analyze the samples. The degradation of picloram in aqueous medium was carried out by direct photolysis and photocatalysis. In direct photolysis, a low rate of product degradation (6.9 %) was obtained after 225 min of irradiation. Photolysis in the presence of a catalyst (TiO2) accelerated the degradation of the molecule. Experiments demonstrating the effect of the concentration of the catalyst showed that the optimum concentration corresponding to a maximum degradation of picloram is 4 mg / L (62.68 %). The study of the influence of the pH of the solution on the degradation indicates that the molecule degrades better in an acid medium (pH = 5) with a rate of 62 % in 225 min -ISSN 1857-7431 518 of irradiation. Apparent order 1 degradation kinetics were observed in all cases.European Scientific Journal October 2017 edition Vol.13, No.30 ISSN: 1857 -7881 (Print) e Keywords: Picloram, Herbicide, Photolysis, Photocatalysis RésuméLe traitement des effluents phytosanitaires s'avère une nécessité vue la stabilité et la toxicité des pesticides qui les génèrent. L'objectif de ce travail est d'étudier la dégradation du piclorame en milieu aqueux sous irradiation UV. Il s'agit d'un herbicide sélectif et systémique qui permet de lutter contre les plantes ligneuses et les dicotylédones. Les irradiations ont été faites à l'aide d'une lampe à vapeur de mercure de longueur d'onde λ=365 nm. Un chromatographe liquide haute performance équipé d'un détecteur UV/visible a permis d'analyser les échantillons. La dégradation du piclorame en milieu aqueux a été réalisée par photolyse directe et par photocatalyse. En photolyse directe, un faible taux de dégradation du produit (6,9 %) a été obtenu après 225 min d'irradiation. La photolyse en présence de catalyseur (TiO2) a permis d'accélérer la dégradation de la molécule. Les expériences mettant en évidence l'effet de la concentration du catalyseur, ont montré que la concentration optimale correspondant à une dégradation maximale du piclorame est de 4 mg/L (62,68 %). L'étude de l'influence du pH de la solution sur la dégradation indique que la molécule se dégrade mieux en milieu acide (pH = 5) avec un taux de 62 % en 225 min d'irradiation. Des cinétiques de dégradation d'ordre 1 apparent ont été observées dans tous les cas.
The study was done on two species of peppers capsicumannuum and capsicum fructescens. It concerned ninety samples of these two species, collected during three countrysides in two localities of Côte d'Ivoire (Bouake and Dabou). These samples were handled by means of a liquid-phase leading chromatograph SHIMADZU with the aim of determining the residues of pesticides. The observed results revealed a contamination of both species : capsicum annuum and capsicum fructescens, indeed, six residues of pesticides (chlorothalonil, chlorpyrifos, carbendazim, maneb, dimethoate and lambdacyaholothrine) were detected in these two species distributed in four families of pesticides (organochlorines, organophosphates, carbamates and pyrethrinoïds). The analysis showed that pyrethrinoïdes with respective proportions of 76,17% and 75,95% in capsicum annuum and capsicum fructescens were the most important ; followed organophosphate with respective proportions of 10,93% and 20,04% in capsicum annuum and capsicum fructescens.The study also showed that the concentrations of residues of pesticides detected in the edible part (pericarp ) peppers are European Scientific Journal February 2018 edition Vol.14, No.6 ISSN: 1857 . L'analyse a montré que les pyréthrinoïdes avec des proportions respectives de 76,17% et 75,95% dans le Capsicum annuum et dans le Capsicum fructescens ont été les plus importants; suivi des organophosphorés avec des proportions respectives de 10,93% et 20,04% dans le Capsicum annuum et dans le Capsicum fructescens. L'étude a également montré que les concentrations de résidus de pesticides détectées dans la partie comestible (péricarpe) du poivron sont sensiblement égales à celles trouvées dans la partie non comestible (pulpe). Cependant, les résidus de pesticides détectés dans les poivrons des deux localités ont tous des concentrations moyennes inférieures aux normes établies par le Codex Alimentarius.Mots-clés : Pyréthrinoïdes, lambdacyaholothrine, Capsicum, annuum, fructescens IntroductionLa Côte d'Ivoire, dans sa politique agricole de diversification et d'autosuffisance alimentaire, s'est orientée dans la production des cultures maraîchères ; notamment dans la production du piment doux (Capsicum) plus connu sous le terme générique de poivron.C'est une plante maraîchère originaire d'Amérique tropicale, très appréciée pour ses fruits surtout consommés en tant que légumes (Tristan,
Metal pollutants constitute one of the major pollution risks in Côte d'Ivoire and in particular in the town of Duekoué. This pollution is problematic due to the non-biodegradability and the accumulation of Trace Metal Elements (TME) in the environment. Thus, the health risk assessment aims to preserve the health of populations in their consumption habits. Indeed, any study aimed at controlling and then monitoring the quality of drinking water and the environment is beneficial. In Duekoué, market garden products grown in the lowlands are consumed without prior treatment which could cause metal poisoning of the population. The objective of this work was to study the behavior of metallic trace elements in the vegetable gardens of the town of Duekoué. To achieve the objective of this work four samples were taken from the four sites at depths of (0 to 15 cm). These samples were analyzed in the laboratory by an atomic absorption spectrometer (AAS). For this purpose, the determination of the concentrations of metallic trace element, pH and the percentage of organic matter of the various samples was carried out. Also our study allowed us to show that soils 1 and 3 are basic while soils 2 and 4 are acidic. In addition, we noticed a richness in organic matter in site 1 with a percentage of 15. 57. In addition, the analysis of the sediments showed that there are correlations between metallic trace elements and factors modifying the mobility of TME and a correlation between TME. In addition, analysis of the samples taken revealed the presence of TMEs including mercury, lead, magnesium and cadmium in the clay fraction of the sediments. Arsenic and chromium are linked to the organic fraction of sediments. From this study, it emerges that the behavior of TME in lowlands is influenced by certain physicochemical parameters such as the pH and the percentage of organic matter in the soil.
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