Zeolites belong to a family of naturally occurring volcanic minerals with unique physical and chemical characteristics. This safe, natural, non-toxic, and inexpensive inorganic material is often called a “molecular sieve” because of its porous structure, and provides proven commercial benefits in a variety of applications. There are over forty-eight varieties of natural zeolite minerals with similar structures and molecular makeups, though each have their own particular attributes – some subtle and some more obvious.

Natural Zeolite Structure – a “Molecular Sieve”

Generally speaking, natural zeolites are hydrated aluminosilicates. They consist of an open, three-dimensional cage-like structure with a vast network of interconnected channels extending throughout – similar to a honeycomb. Loosely bound, positively charged atoms called cations, are attached at the junctures of the negatively charged aluminosilicate lattice structure. The aluminosilicate framework provides exceptional strength and stability to the lattice structure.

The channels, typically 0.3 to 0.7 nanometers in diameter (slightly larger than a water molecule), selectively screen molecules according to size and exchangeable cations. Molecules too large to pass through the entry channel are excluded, thus giving rise to the term “molecular sieve.”

Zeolites in general have high specific surface areas and their rigid framework limits shrinking and swelling. However, the molecular structure, surface area, surface charge density, and cation exchange capacity (CEC) of each particular zeolite will determine its loading, shrinking, swelling, and stability under various conditions.

Cation Exchange Capacity – Purification, Separation and Decontamination

Perhaps the most commercially valuable and dynamic property of zeolite is its cation exchange capacity (CEC). Cation exchange occurs when two or more positively charged compounds or elements exchange places on a negatively charged host, binding one cation to the zeolite and releasing another. The most common exchangeable cations found in natural zeolite molecules are sodium, calcium, potassium, and magnesium, many of which are desirable in numerous biological and industrial processes.

The ability to release beneficial elements while capturing and binding other, often less desirable, materials makes zeolite an ideal media for the selective adsorption of certain elements and compounds from soil, water, and air.

A classic example of cation exchange is the removal of ammonia from water and air. When a molecule of ammonia (NH3) is hydrated, the reaction produces ammonium (NH4+), which is readily exchanged for all or part of the calcium, potassium, and magnesium cations contained in zeolite and adsorbed on to its stable aluminosilicate lattice.

St. Cloud Zeolite – A Uniquely Valuable, Innovative Solution

All zeolites are not created equal. The same can be said about zeolite producers. Too many producers promote a “one size fits all” solution to all problems and applications. Nothing could be more detrimental or misleading. Every zeolite mine produces a unique mineral. A zeolite best suited for radionuclide removal may not perform well in agricultural applications.

St. Cloud owns, mines, and mills three separate zeolite deposits and controls a large drilled out deposit of mordenite (a zeolite mineral), currently under evaluation. We will collaborate with you to identify the most effective zeolite for your particular requirement.

The Winston deposit is characterized by its high surface area, high surface charge density (readily available cation exchange sites), and physical durability. Its high calcium and low sodium content make it preferable in agricultural applications, while its low clay content makes it desirable in water treatment applications. Its versatility, combining numerous commercially desirable properties for use in a broad range of applications, make it the largest single selling zeolite in North America.

The Ash Meadows Zeolite deposit is characterized by its purity, high cation exchange capacity (CEC), extensive surface area, and structural durability. Its chemical composition, high CEC, and abrasion resistance make it an ideal water filtration media. Ash Meadows Zeolite is requested by name by numerous buyers for their ongoing requirements and for special project applications.

Bowie Chabazite (a zeolite mineral) is rarely occurring and unique among natural zeolites, and has been called for in critical response efforts such as the Fukushima Nuclear Plant and Three Mile Island clean-ups. It is characterized by its light weight, extremely high surface area, and high CEC. Its chemical composition and affinity for radionuclides make it a proven and highly effective media for the toughest environmental remediation applications, and its high surface area is valued in gas separation and specialty desiccant markets.