The Removal of Cadmium, Cobalt, and Nickel by Adsorption with Na-Y Zeolite

The article aims to study the removal ofheavy metal ions Cd2+, Co-2+,Co- and Ni2+ from aqueous solution using faujasite NaY. The adsorption studies were carried out in the single and binary component system. Sorption experiments were performed in batch at pH (5-6), adsorbent dosage (0.15 g), and initial concentration (0.1-10 mmol/L). The single-ion equilibrium adsorption data were fitted to three isotherm models: Langmuir, Freundlich, and Dubinin-Radushkevich. Results showed that the Langmuir isotherm fits sorption data better than the Freundlich equation. The maximum adsorption capacities (Q(max)) were 0.81, 0.85 and 0.92 mmol/g for Cd2+, Ni2+ and Co2+ ions, respectively. Besides, the study of the competitive sorption of ions in a binary system showed that faujasite NaY preferentially adsorbs cations in the following order: Co2+>Ni2+>Cd2+. The obtained & (separation factor or Langmuir parameter) values were in the range of 0-1 indicating that Cd2+, Co-2+,Co- and Ni2+ sorption were favorable. The obtained mean free energy value for adsorption of Co2+ and Ni2+ were in the range of 8-16 kJ/mol, indicating that ions were uptaken through an ion exchange process.