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

The article aims to study the removal of heavy metal ions Cd2+, Co2+, 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 (Qmax) 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 RL (separation factor or Langmuir parameter) values were in the range of 0–1 indicating that Cd2+, Co2+, 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.