Herbicide Langmuir Freundlich % Adsorption • Ga qm b R2 Kf 1/n R2 Atrazine 5000 20 0.997 11954 0.57 0.980 98.4-100 -5.59 Metribuzin 2500 20 0.984 5626.0 0.53 0.978 95.3-99.2 -5.27 Metolachlor 3333 300 0.906 3946.4 0.36 0.961 94.2-100 -5.07 Alachlor 20000 0.5 0.998 5959.4 0.95 0.999 93.8-94.2 -5.18

aKcal mol-1

Table 3: Freundlich and Langmuir adsorption-desorption parameters for herbicide adsorption on granular carbon.