Natural Zeolites: Industrial and Environmental Applications, pp. 23-49
Authors: (Antonis Zorpas, Vassilis J. Inglezakis - ENVITECH (Institute of Environmental Technology and Sustainable Development, Cyprus)
Abstract: Natural zeolites are the least-known treasures for industrial applications, environmental pollution control, separation science and technology. Natural zeolites are volcanic minerals with unique characteristics. Their chemical structure classifies them as hydrated aluminosilicates, comprised of hydrogen, oxygen, aluminum, and silicon, arranged in an interconnecting lattice structure. The arrangement of these elements in a zeolite crystal gives rise to a honeycomb framework with consistent diameter connecting channels that vary in size from 2.5 to 5.0 angstroms, depending on the type of zeolite mineral. This unique structure makes zeolites different from "other" aluminosilicates (kaolin, bentonite, etc.) due to the following special properties: the ability to selectively adsorb molecules of gases and vapors, the ability to reversibly absorb/desorb water without any chemical or physical change in the zeolite matrix and the ability to exchange inherent cations for other cations on a basis of ion selectivity. The present chapter is an up-to-date review of the utilization of natural zeolites in environmental-related applications and more specifically in the field of wastewater treatment and solid waste treatment. The review will present the current status and future developments in basic research as well as in the commercial applications.