Removal of Heavy Metals Cd (II), Fe (III) and Ni (II), from Aqueous Solutions by Natural (Clinoptilolite) Zeolites and Application to Industrial Wastewater

The adsorption mechanism of Cd, Fe, and Ni, ions on natural (clinoptilolite) zeolites, a regional low-cost natural available adsorbent was studied in a batch adsorption system. The effect of several parameters such as contact time, zeolite dose, particle size, the effect of pH, and initial concentration of metal ions in the adsorption process was estimated. The optimum adsorption was found to occur at pH 6.0, adsorbent dose 1.0 g/L, and initial concentration 2, 20 and 10 mg/L for Cd, Fe, and Ni, respectively. The adsorption efficiency also increases with decreasing particle size of zeolites and the effect of retention time on adsorption ratio shows that 80% of the Cd, Fe, and Ni, are adsorbed by zeolite during first 120 minutes. Under these optimum conditions, the removal efficiency was 78.8, 89.1, and 65.5% of Cd+2, Fe+3 and Ni+2, ions, respectively. Sorption data have been interpreted in terms of Langmuir and Freundlich isotherms. The adsorption efficiency of heavy metals in industrial wastewater as application mode was also investigated using zeolites and these results showed that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater and confirms the potential use of zeolite for the removal of heavy metals from industrial wastewater via adsorption. It was concluded that zeolite is very promising for the removal of metal ions from aqueous solution and hence we encourage the utilization of zeolites in environmental applications.