The Impact of Pesticides - Academy Publish

RESULTS AND DISCUSIONEquilibrium isothermIn order to obtain the adsorption isotherm, additional batch experiments werecarried out to find out the equilibrium data. In this sense, experiments wereconducted for various time intervals to determine the time required to reachadsorption equilibrium (Fig. 1). The equilibrium state was considered reached afterabout 300 hours, since the variations in equilibrium adsorption capacity did notchange more than 5%.Fig.1. Equilibrium time of isoproturon.300250200q eq/ mg.g -115010050Isoproturon00 5000 10000 15000 20000t / minThis contaminant, as seen in Fig. 2, presents a type of isotherm can be fitted toFreundlich model (the R 2 value for linear fit is 0.9999). This isotherm is L1-typeaccording to the Giles classification (Giles and Nakhwa, 1960), indicating a highaffinity adsorbent-adsorbate and suggesting that isoproturon molecules are adsorbedin parallel to the carbon surface and that there is no major competition betweenadsorbate and water molecules for the active adsorption sites on the activatedcarbon.Fig.2. Adsorption isotherm of isoproturon.350300250q eq/ mg.g -120015010050Isoproturon00.0 0.5 1.0 1.5 2.0 2.5 3.0C eq/ mg.L -1AcademyPublish.org - The Impact of Pesticides344