Influence of Methanol on the Dynamics of the Retention and Release of Cyprodinil by an Agricultural Soil

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• 作者：José ; Eugenio Ló ; pez-Periago ; Manuel Arias-Esté ; vez ; Benedicto Soto-Gonz&aacute ; lez ; Sara Trelles-Reinoso ; and Jesú ; s Simal-G&aacute ; ndara
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2006
• 出版时间：June 28, 2006
• 年：2006
• 卷：54
• 期：13
• 页码：4751 - 4757
• 全文大小：136K
• 年卷期：v.54,no.13(June 28, 2006)
• ISSN：1520-5118

文摘

The influence of methanol on the adsorption of the fungicide cyprodinil by a crop soil was studied byequilibrium measurements and by determining the retention-release dynamics in a continuous stirredflow tank reactor (CSTR). Equilibrium measurements showed the effective coefficient of partition ofcyprodinil between soil and solution, K_dc, decreases linearly as the concentration of methanol in thesolution increases until a percentage of 20% is reached. In CSTR experiments, the retention ofcyprodinil was found to be almost reversible; up to a 95% of the fungicide was desorbed. Theretention-release dynamics showed biphasic behavior and was partially controlled by diffusion. Thisbehavior was reproduced by a model of diffusion into micropores identifying the soil particles asspheres and taking into account both intraparticle nonlinear adsorption and nonlinear adsorption atexternal surfaces. In all cases, the sorption kinetics was not the limiting step. The main effect ofmethanol in the retention-release dynamics ended up being based on the changes produced in theadsorption equilibrium. Methanol also increased the effective diffusion coefficient and decreased themass transfer coefficient. The optimized Freundlich's isotherm coefficients for <5% methanol werelower than those obtained from the batch experiments.Keywords: Cyprodinil; adsorption; kinetics; stirred flow