Sorption and Leaching Properties of the Composites and Complexes of Natural Microporous Materials

This contribution deals with those aspects of the application of natural microporous materials (NMM), which are projected for a millennial horizon of environmental protection. Though the NMM possess excellent sorption properties, their natural physico-mechanical form usually limits their application in technological processes, such as packed-bed columns. However, due to their thermal and radiation stability, compressive strength, steadiness towards the freezing/ thawing and wetting/ drying cycles, they have received increasing interest in the long-term hazardous waste treatment both in situ and plant performance. To improve mechanical properties of crystals, solid carriers such as cellulose and carbon, or binders such as organic polymers, are applied. Artificial formation of composites and both inorganic and organic complexes of NMM is applied for: (1) field barriers (mortars and grouts), (2) reagents and organic coating supports, (3) granules, pellets and column packings, (4) additives to cementitious fixation matrices, and (5) ceramics and glass formulations.In natural conditions, by application of NMM engineering barriers, the complexes of NMM with natural organic components, namely humic substances, play an important role in the modification of their sorption properties and the immobilisation of pollutants. NMM have a marked superiority over commercially available cation exchange organic resins, due to high cation exchange capability, thermal and radiolytic stability, the possibility of transformation to stable ceramics and their compatibility with cement. Glass-bonded NMM are being developed as a potential ceramic waste form for the disposition of radionuclides. An overview of the various problems to be solved is presented and selected papers in the field from the last two decades are reviewed and indexed comprehensively.