Zeolite

The hydrated cations interrupt the otherwise dense network of Si-O-Al, Si-O-Si, and Al-O-Al linkage, leading to regular water-filled cavities.

The term molecular sieve refers to a particular property of these materials, i.e., the ability to selectively sort molecules based primarily on a size exclusion process.

The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the dimensions of the channels.

Zeolites also crystallize in post-depositional environments over periods ranging from thousands to millions of years in shallow marine basins.

For this reason, naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential.

Some examples:[15] Thomsonites, one of the rarer zeolite minerals, have been collected as gemstones from a series of lava flows along Lake Superior in Minnesota and, to a lesser degree, in Michigan.

Thomsonite nodules from these areas have eroded from basalt lava flows and are collected on beaches and by scuba divers in Lake Superior.

These thomsonite nodules have concentric rings in combinations of colors: black, white, orange, pink, purple, red, and many shades of green.

Major producers in 2010 included China (2 million tonnes), South Korea (210,000 t), Japan (150,000 t), Jordan (140,000 t), Turkey (100,000 t) Slovakia (85,000 t) and the United States (59,000 t).

These materials are used for construction, e.g. dimension stone (as an altered volcanic tuff), lightweight aggregate, pozzolanic cement, and soil conditioners.

[21] Most zeolites have aluminosilicate frameworks but some incorporate germanium, iron, gallium, boron, zinc, tin, and titanium.

Research into and development of the many biochemical and biomedical applications of zeolites, particularly the naturally occurring species heulandite, clinoptilolite, and chabazite has been ongoing.

Evidence for the oldest known zeolite water purification filtration system occurs in the undisturbed sediments of the Corriental reservoir at the Maya city of Tikal, in northern Guatemala.

[27] Synthetic zeolites, like other mesoporous materials (e.g., MCM-41), are widely used as catalysts in the petrochemical industry, such as in fluid catalytic cracking and hydrocracking.

Zeolites containing cobalt nanoparticles have applications in the recycling industry as a catalyst to break down polyethylene and polypropylene, two widely used plastics, into propane.

For example, in the aftermath of the Fukushima Daiichi nuclear disaster, sandbags of zeolite were dropped into the seawater near the power plant to adsorb the radioactive cesium-137 that was present in high levels.

[29] Zeolites have the potential of providing precise and specific separation of gases, including the removal of H2O, CO2, and SO2 from low-grade natural gas streams.

announced that they had developed a zeolite substance for use in the biogas industry for long-term storage of energy at a density four times greater than water.

Debbie Meyer Green Bags, a produce storage and preservation product, uses a form of zeolite as its active ingredient.

Clinoptilolite has also been added to chicken food: the absorption of water and ammonia by the zeolite made the birds' droppings drier and less odoriferous, hence easier to handle.

[37] In these applications, their high heat of adsorption and ability to hydrate and dehydrate while maintaining structural stability is exploited.

[non-primary source needed] Synthetic zeolites are used as an additive in the production process of warm mix asphalt concrete.

They help by decreasing the temperature level during manufacture and laying of asphalt concrete, resulting in lower consumption of fossil fuels, thus releasing less carbon dioxide, aerosols, and vapors.

The use of synthetic zeolites in hot mixed asphalt leads to easier compaction and, to a certain degree, allows cold weather paving and longer hauls.

[39][40] Non-clumping cat litter is often made of zeolite (or diatomite), one form of which, invented at MIT, can sequester the greenhouse gas methane from the atmosphere.

[41] The original formulation of QuikClot brand hemostatic agent, which is used to stop severe bleeding,[42] contained zeolite granules.

[43] The 2022 formulation of QuikClot uses a nonwoven material impregnated with kaolin, an inorganic mineral activating Factor XII, in turn accelerating natural clotting.

Pet stores market zeolites for use as filter additives in aquaria,[20] where they can be used to adsorb ammonia and other nitrogenous compounds.

Zeolite filtration is also used in some marine aquaria to keep nutrient concentrations low for the benefit of corals adapted to nutrient-depleted waters.

For instance, nitrate fertilisers are water soluble and prolonged exposure by dairy cattle is known to impair protein metabolism and glucose utilization.