Table 3.

Main advantages and limitations of using natural zeolites for environmental remediation.

Advantages

Limitations

•Simultaneous interaction with contaminants by ion exchange and sorption of molecules and ions •High degree of crystallinity •Low density material •Large internal surface area and volume •Reversible hydration and dehydration •Shape selectivity •Low-cost material and widespread worldwide •Rock with low hardness which makes them easy to process •“Ready-to-use” for many applications after a minimum processing (crushing and heating) •May be used for multicomponent purposes

•Natural zeolitic tuffs contains a mixture of minerals •Exchangeable cations in natural zeolites are highly variable •Degree of crystallinity varies •Internal surface area, internal volume and pore radius are variable •Low adsorption capacity for some substances, modification can be necessary •Their affinity is mainly for cations, modification is required for other substances •Variable properties even in same quarry •May contains impurities, including traces of heavy metals, requiring thus purification, or restricted uses for some purposes