Analytical grade reagents are used in all experiments. Acid dye, CB (99 %) is purchased from Merck Company. The chemical structure and properties of CB are listed in Table 1. Apricot stones obtained from Boumerdes region in Algeria, are air-dried, crushed and screened to obtain two fractions with geometrical mean sizes ranging from 63 to 2.5 mm. 100 g of the selected fraction are impregnated with concentrated