Comparative Study of Copper Adsorptivity and Selectivity toward Zeolites

Abstract

The objectives of the study were to find the type and species of zeolite which gives optimum adsorption of copper, provide an explanation of the mechanism involved in the adsorption process and establish the selectivity sequence among zeolites. Adsorption of Cu onto zeolites and mont-morillonite as a reference was conducted at an initial Cu concentration range of 0 - 0.60 mM in the presence of 100 mM NH₄NO₃ at initial pH of 5. Langmuir and Freundlich models were used in analyzing the equilibrium data and a selectivity sequence derived from the Langmuir calculation was A4 > faujasite X > modernite > Na-P1 ≈ montmorillonite ≈ faujasite Y > clinoptilolite. Zeolites A4 and faujasite X had high adsorptive capacities of 1429 mmol·kg^﹣1 and 909 mmol·kg^﹣1, respectively. Zeolite A4 has the highest CEC among all the samples (6150 mmol·kg^﹣1), and the adsorption capacity of Cu was largely influenced by the CEC of the samples. The adsorption mechanism was based on the exchange of Cu from solution with mostly Na which was the main exchangeable cation available. These results are important in selecting the most effective and suitable adsorbent for Cu removal from polluted environments.