Comparison of Adsorption Capacity of Metal Pollutants by Synthetic and Natural Zeolites

Zeolites are crystalline aluminosilicates with the structure based on tetrahedral SiO4 and AlO4 units, connected by shared oxygen atoms, they are one of the synthetics inorganic cationexchangers and commonly used as commercial adsorbents. As of January 2008, 175 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known. Zeolites have a porous structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and others. Silicon is tetravalent and aluminum is trivalent, which result in negatively charged framework structures. Thus, These positive ions are rather loosely held and can readily be exchanged for others in a contact solution and each mole of aluminum produces one equivalent of cation exchange capacity for the zeolite framework. In this study, The removal capacity of heavy metals by natural and Synthetic Zeolites from liquid wastes compared together. Among natural zeolites, clinoptilolite exhibited high selectivity for certain heavy metal ions such as Pb2+, Cd2+, Zn2+, and Cu2+. The stability of the adsorbent–adsorbat products was studied through desorption experiments. These elements are principal heavy metals responsible for causing degradation of the environment, and although essential for leaving in low concentrations, both acute and chronic exposure to excess metals are associated with various health effects. Such water has to be treated, and with respect to water quality standards, the concentration of the these metals ions in wastewater should be reduced to standard quantity.

Keywords:

Natural zeolite , synthetic zeolite , metal pollutant , wastewater