Superoverpack: Tailor-Made Mixtures of Zeolites and Clays
Cation exchange and selective adsorption of cations by clays, zeolites and gels is well known and has been the subject of intensive research for decades. Numerous equations have been derived to describe the exchange of ions by clay systems (1, 2), and selective sorption of cations by clays has been long studied (3–5). Ion exchange has been established as a standard way of describing molecular sieve zeolites (6), and selectivities shown by a number of zeolites for Cs or NH4 or K (7–9) illustrate a few of many ion separations which could be performed with zeolite exchangers. Hydrous metal oxides typically as noncrystalline oxyhydroxide gels have also been extensively studied for the selective sorption of cations (10, 11). The vast majority of these studies of cation exchange equilibria and of selective adsorption have been made on single cation exchangers, i.e., the solution from which sorption occurs typically contains only one cation. Moreover, most of the work also involves one solid phase at a time, and little attention was paid as to what extent the sorbed ions are retained or fixed by the solid phase. Very little work has been done on adsorption and fixation of complex mixtures of ions by mixtures of clays and zeolites.
KeywordsClay Mineral Sorption Capacity Radioactive Waste Fission Product Natural Zeolite
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