Natural Zeolites as Sustainable and Environmental Inorganic Resources over the History to Present

Abstract

Zeolites synthetic as well as natural, based on their beneficial properties and economic value, represent for a long time recognized industrial commodities. Natural zeolites are highly porous, hydrated aluminosilicates with a rigid crystalline structure and a network of interconnected tunnels and cages (such as honeycomb). Total pore volume of some natural zeolites reaches up to 35%. Their structures consist of a three dimensional framework, having a negatively charged lattice. The negative charge is balanced by cations, which are exchangeable with certain cations from aqueous or gaseous media. Based upon these facts and according to a new definition, zeolites are also clathrates or inclusion compounds, able to host various guest substances in their versatile structures and thus enhance their adsorption potential to broaden range of pollutants.