Removal of Ni and Cd ions from aqueous solution using iron dust-zeolite composite: analysis by thermodynamic, kinetic and isotherm studies

To examine the effectiveness of iron dust-zeolite composite as an adsorbent for the removal of heavy metal ions from aqueous solutions, the adsorption isotherms, the kinetic, thermodynamic and optimum conditions such as initial concentration, pH, contact time, adsorbent dosage and competitive adsorption conditions of heavy metals were investigated. The characterization of the composite was characterized via FTIR, SEM, XRF and XRD methods. Kinetic results on the removal of heavy metal ions from aqueous solutions have been well described by the pseudo-second-order model. The adsorption data for Cd and Ni ions were fitted well with the Langmuir and Freundlich isotherm models, respectively. The maximum adsorption capacities of iron dust-zeolite for Cd and Ni ions were equal to 78.125 and 76.33 mg/g, respectively. The thermodynamic parameters such as enthalpy, entropy and free energy of adsorption of metal ions were determined. It was found that the process is endothermic, favorable and spontaneous. The competitive adsorption ability of heavy metal ions in the binary system on the composite showed that Cd ions had a synergistic effect on the adsorption of Ni and Ni ions had the negative effect on Cd adsorption.