Natural zeolites in environmentally friendly processes and applications

An outline of the occurrences, features and environmental uses of the main sedimentary zeolites, namely chabazite, clinoptilolite, mordenite and phillipsite, is presented. After pointing out that zeolite-bearing rocks should not be considered as substitutes for synthetic zeolites, as they are lacking of purity and constancy of composition, three major areas of environmental application are identified: soil amendment, cement manufacture and wastewater purification. Present and perspective utilizations in these areas are dealt with and discussed, giving also a few information on the use of natural zeolites as adsorbents and catalysts.