zeoliitit

Zeoliitit, or zeolites, are a family of hydrated aluminosilicate minerals and synthetic crystalline materials known for their three-dimensional framework of SiO4 and AlO4 tetrahedra. The framework carries a negative charge that is balanced by exchangeable cations such as sodium, potassium, or calcium. This arrangement creates uniform, rigid pore systems with molecular-sized channels, giving zeolites distinctive adsorption, ion-exchange, and catalytic properties that resemble molecular sieves.

Natural zeolites form in volcanic rocks and sedimentary environments through the alteration of aluminosilicate materials in the presence of water and alkaline conditions. Common natural zeolites include clinoptilolite, mordenite, chabazite, and erionite, though some forms can raise health concerns if fibrous. Synthetic zeolites are produced industrially by hydrothermal synthesis from alumina, silica, and structure-directing agents, yielding well-defined frameworks.

Zeolites are classified by their framework types, such as FAU (faujasite; includes zeolite Y), LTA (zeolite A), and MFI (ZSM-5), among others. These materials act as ion exchangers and catalysts, and as highly selective adsorbents. In catalysis, acidic zeolites provide active sites for petrochemical refin­ing, cracking, and hydroisomerization. In adsorption and separation, they remove water, gases, and pollutants, and they are used in detergents, air and water purification, and agriculture.

Safety and handling vary by form. Synthetic zeolites are generally considered low in toxicity, while certain natural variants can pose inhalation or fibrous hazards, necessitating appropriate handling and exposure controls.