Cinética e termodinâmica de sorção do inseticida clorpirifós em latossolo vermelho-amarelo

• Ano de defesa: 2011
• Autor(a) principal: Marcelo, Luciana Resende
• Orientador(a): Lima, Claudio Ferreira
• Banca de defesa: Fontes, Maurício Paulo Ferreira , Oliveira, André Fernando de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Pesticidas; Solo; Adsorção; Cinética; Isotermas
• Palavras-chave em Inglês: Pesticide; Soil; Adsorption; Kinetics; Isotherms
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2104

Use of chemicals in agriculture has increased greatly in the last 50 years. The misuse and abuse of these synthetic chemicals has caused contamination of the environment and for this reason the performance assessment of these compounds in the environment deserves careful attention. This work aimed to study the kinetics and thermodynamics of adsorption of the insecticide chlorpyrifos in a Red-Yellow Latosol in Viçosa, MG. The behavior of the insecticide was assessed by the influence of initial concentration of insecticide and temperature on the phenomenon of adsorption. The kinetic studies of sorption of chlorpyrifos in the soil were performed by adding 10.0 mL of chlorpyrifos obtained from the commercial product in increasing concentrations of the active ingredient to 1.0000 g of dry matrix, under stirring at different times and at different temperatures. After agitation and centrifugation, the insecticide was extracted from the supernatant and analyzed by gas chromatography. In the extraction of chlorpyrifos in the supernatant was used Liquid-Liquid Extraction technique to partition at low temperature (PBT-ELL) and for quantification, it was used gas chromatography (GC) with electron capture detector (GC-ECD). For the equilibrium study it was conducted the same procedure described for the kinetics study keeping the stirring time of 3 h (equilibrium time predetermined). The kinetics of adsorption was analyzed by adjusting the data according to the model of pseudo-second-order and fot the thermodynamic equilibrium it was applied the Freundlich equation. The adsorption decreases with increasing initial concentration of chlorpyrifos requiring longer times to establish the equilibrium. The adsorption is influenced by the temperature increase caused a slight decrease in the rate constant. Thermodynamic parameters of free energy, enthalpy and entropy calculated show that the process is exothermic and spontaneous.