Intake of divalent copper and nickel onto natural zeolite from aqueous solutions: a study in mono- and dicomponent systems

In this study, the noncompetitive and competitive adsorption process of copper (II) and nickel (II) ions on the natural zeolite were examined in simulated wastewater in a batch system with respect to concentration, pH and temperature. Optimum pH values were found as 5,0 for adsorption of copper and nickel ions on the zeolite. The effect of initial concentration and ambient temperature on the yield of adsorption was examined at this pH value. The equilibrium adsorption data of Cu (II) and Ni (II) onto the zeolite were analyzed by the Langmuir’s and Freundlich’s isotherms, and the experimental metal uptake data fitted well with both isotherm models. In case of the presence of simultaneous multimetal ions in the aqueous phase, the adsorption capacity of the adsorbent is slightly low probably due to the competitive uptake of each metal ion by the adsorbent. For the metal sorption system, the negative Gibbs free energy values show the applicability and spontaneous nature of the metal uptake treatment by the zeolite. The activation energy and enthalpy change of divalent cation adsorption demonstrate that the intake of Cu (II) and Ni (II) onto the zeolite involves not only a chemical adsorption process but also a physical adsorption process.