LAUSR

Eggshells was used as a natural adsorbent to remove direct blue(DB) dye from aqueous solution and investigating the four factors that affect the adsorption of DB dye ; amount of eggshell rang (0.1 - 1g), initial concentration (10 - 60 mg/L ), time ( 5 - 45 min.) and pH (3 - 11). Central Composition Design with four variables and five levels coupled with response surface method was adopted to get a second order polynomial equation for dye removal percentage as the response, and to obtain the optimum conditions for maximum dye removal percentage ; which reach 84% with optimum point , eggshell (0.835 g) ,time (24min.) , initial dye concentration ( 10 mg/L) , pH (4.2). The most effecting factors on dye removal are pH and initial dye concentration. Langmuir, Freundich model gives good fitting with (R2 ]0.98). The process of adsorption of DB dye on eggshell fitted a pseudo-second order kinetic model.