Abstract

DUDAMEL D, Wilmer J  and  WOLBERT, Dominique. Non-isothermic modeling of pesticides in aqueous phase on activated carbon at equilibrium. INCI [online]. 2008, vol.33, n.1, pp.14-21. ISSN 0378-1844.

The modeling of the non isothermic adsorption of pesticides in aqueous solution on activated carbon and the analysis of parameters in the selected models was carried out using three activated carbons, one produced in Venezuela (V-100) and two widely used in Europe (Chemvirom Filtrasorb 400 and carbon picatif NC90). Two pesticides were considered, Atrazine and Imidaclopride, and eleven equilibrium models were analyzed: Freundlich, Langmuir, Langmuir-Freundlich, Fowler-Guggenheim, Hindarso, Temkin-Frumkin, Temkin, Khan, Toth, Dubinin-Astakhov and Jaroniec-Choma. Equilibrium parameters for these models were determined through minimization of the difference between the quantity of pesticide adsorbed experimentally and that calculated according to the model, using SOLVER of Microsoft EXCEL. To discriminate the mentioned models, coherence of results, parameter variance analysis and physical hypothesis that were used to build the models were considered. Four models presented enough precision and they were physically exact: Freundlich, Langmuir-Freundlich, Fowler-Guggenheim and Dubinin-Asthakhov. An analysis of parameters of the selected models evidenced the influence of the characteristics of the activated carbon and pesticides used. The visualization of a superposition phenomenon between the Freundlich and Langmuir-Freundlich models, using the pondered distribution by the number of adsorption sites, showed that the Freundlich model better represents the distribution sites used by the pesticide in adsorption conditions. A linear regression was obtained, with good correlation, between volume of micropores and adsorption capacity for most of the selected models.

Keywords : Adsorción no Isotérmica ; Carbón Activado ; Micropoluentes Orgánicos ; Plaguicidas.