zeolity

Zeolites, known in Polish as zeolity, are a family of microporous aluminosilicate minerals and synthetic materials characterized by a three-dimensional framework of linked silicon–oxygen and aluminum–oxygen tetrahedra. Substitution of aluminum for silicon introduces a negative framework charge balanced by extra-framework cations such as Na+, K+, or Ca2+. This creates rigid, porous solids with well-defined channels and cages that enable selective adsorption, ion exchange, and shape-selective catalysis.

Natural zeolites form in volcanic and hydrothermal settings and include clinoptilolite, mordenite, chabazite, and erionite. They have long been used for water treatment and soil conditioning. Synthetic zeolites are produced by hydrothermal crystallization of silica–alumina gels to achieve precise pore structures. Common commercial types are zeolite A (LTA), X and Y (FAU), and MFI-type zeolites such as ZSM-5.

Key properties include high surface areas, framework acidity from aluminum, and uniform microporosity. Applications span ion exchange (water softening), adsorption (gas and liquid separations), catalysis (petrochemicals, fine chemicals), and catalyst supports. They are also used as slow-release carriers in agriculture and as components in detergents and air-purification systems.

Pore openings are described by size classes, such as 3A, 4A, 5A and 13X, reflecting nominal channel diameters and cages. Zeolite performance is tuned by framework type, Si/Al ratio, and the nature of exchangeable cations.

Safety considerations include potential contamination of natural zeolites with heavy metals and, for erionite, carcinogenic risks when inhaled. Handling should follow regulatory guidance to minimize exposure during mining, processing, and use.