Adsorption of Cadmium Ions onto Zeolite-A prepared from Egyptian Kaolin using Microwave Technique

Zeolite-A has been prepared from Egyptian kaolin to remove divalent cadmium ion from wastewater. The synthesized zeolite was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A batch technique was employed as a function of temperatures, contact time and pH of the solution. Zeolite-A morphology was observed by SEM analysis, and it showed well-defined crystals slightly different sized crystals of the same cubic shape. Results revealed that the optimum conditions of the adsorption process are zeolite dose= 0.25g in 25 mL of Cd (II) with contact time of 140 min, 333 K and pH 7.5. Two equations, namely pseudo-first order and pseudo-second order have been used to determine the kinetics of removal process. The collected kinetic data showed that pseudo-second order equations controls the adsorption. Chemisorption process and Langmuir isotherm proved best fitting to the experimental data. The adsorption mechanism was based on cation exchanges of Cd2+ ions present in wastewater and the available Na+ ion.