Cement Kiln Dust

The adsorption of Murexide, Eosin yellowish and Bromo cresol green(BCG) dyes by CKD was carried out by varying the parameters such as contact time, dye concentration, adsorbent dose, pH and temperature. Adsorption isotherm equations were tested for all of Langmuir, Freundlich, Temkin, Modified Frumkin, Dobinin-Radushvich, Harkins-Jura and Elovich. The equilibrium adsorption data were fitted between Freundlich and Temkin isotherms for Murexide, D-R isotherm for Eosin yellowish and Freundlich for BCG. Adsorption followed pseudo-second-order rate kinetics. The high percentage removal was found ≈ 80.2% at 333K , pH 6  ;  ≈ 42% at 303K,  pH 6; and ≈ 50% at 303K, pH 5 of Murexide, Eosin yellowish and BCG respectively. Thermodynamic parameters ΔG, ΔH, ΔS and Ea were computed ,and showed that the  adsorption process onto CKD was endothermic and spontaneous in Murexide adsorption process, while in Eosin yellowish and BCG adsorption was exothermic and spontaneous. Also adsorption studies suggest that physisorption might be the major mode of adsorption and CKD expressed as low affinity for removal of Eosin yellowish and BCG  and  in general the adsorption process was less affected by temperature .