Zeolites are highly crystalline hydrated aluminosilicates that, when dehydrated, develop, in the ideal crystal, a porous structure with minimum pore diameters, that is, from 3 to 10 angstroms. An aluminosilicate is a mineral containing aluminum oxide (Al2O3) and quartz (SiO2).
The general chemical formula of zeolites can be expressed as (Al2O3)x(SiO2)y(H2O)z, where «x», «y», and «z» are integers that vary depending on the specific type of zeolite.
The structure of pores and channels in zeolites is formed by aluminum and silicon tetrahedra joined by oxygen atoms. Thanks to this formation, the ability to adsorb and selectively desorb water molecules and other compounds, as well as allow the capture of ions, organic and inorganic molecules, makes this material ideal for a wide range of applications, such as water filtration, food supplements for humans and animals, fertilizers, cat litter, raw materials, and construction.
These minerals were discovered in 1756, and since then, great interest has been aroused in learning More about them. Zeolites are a stone mineral unique in their structural property, and due to the large deposits in Cuba, they were awarded the title of “magic rock.”
Types of zeolites
There are more than 40 types of natural zeolites, and each has unique properties. Some typical zeolites include clinoptilolite, mordenite, ferrierite, and heulandite. However, clinoptilolite zeolite is especially noted for its applications in water treatment due to its high ion exchange capacity and porous structure. The six most widely used zeolites are:
- Clinoptilolite Zeolite has a high ion exchange capacity and is especially effective in adsorbing ammonium and heavy metals in water treatment applications. Due to its unique porous structure, it is one of the most used.
- Mordenite Zeolite: This zeolite stands out for its ability to adsorb larger molecules, such as organic compounds. It is used in the detergent industry, oil and gas production, and environmental applications, such as removing contaminants in soils and groundwater.
- Zeolite Ferrierite: This variety has a porous structure that is suitable for the adsorption of large molecules and the separation of isomers. It is commonly used in separation and catalysis processes.
- Zeolite Heulandite is effective in adsorbing metal ions and organic compounds. It is also used in water treatment and in removing impurities.
- Zeolite ZSM-5: This type, with a structure of smaller pores, is recommended for the conversion of large molecules in catalysis processes. It is used in the petrochemical industry and in the production of chemical products.
- Zeolite Beta: Its uniform pore constitution allows the adsorption of large molecules and the conversion of chemical products. It is used in the chemical and petrochemical industry to produce fuels and high-value chemicals.
- Zeolite Faujasite: This zeolite has a porous structure and can retain large molecules. It is widely used in the petroleum industry for catalytic cracking, a process that converts heavy hydrocarbon molecules into lighter products, such as gasoline.
Zeolite clinoptilolite: one of a kind
Clinoptilolite zeolite is widely used due to its specific crystal structure, which allows high ion exchange and adsorption capacity. This means that it can selectively trap and retain unwanted ions and compounds in water, such as ammonium, heavy metals, and organic contaminants. This capacity is crucial in water treatment applications, where efficient removal of impurities is essential.
Physical characteristics of clinoptilolite zeolite
- Color: Usually white to pink
- Hardness (Mohs scale): 35 – 40
- Specific weight: 20 – 25 g/cm³
- Crystalline structure: Orthorhombic
- Specific surface: 20 – 40 m²/g
- Average particle size: 02 – 20mm
- Porosity: high
- Water absorption: up to 25%.
Chemical characteristics of clinoptilolite zeolite
- Chemical composition: (Na, K2, Mg, Ca)3-4[Al5Si11O28]•nH2O.
- Ion exchange capacity: High, especially for ammonium and heavy metals
- Regeneration: Yes, by washing with appropriate solutions.
- Chemical stability: Stable in aqueous solutions and at moderate temperatures.
- Toxicity: Non-toxic
*Data may vary depending on the origin of the mineral, as well as the percentage of its quality.
Quality and purity of zeolite
The quality and purity of the zeolite are crucial factors in its effectiveness. The presence of impurities can decrease its adsorption capacity and affect its performance. Therefore, significant attention is paid to the quality and purity of the zeolite used in water treatment applications. To identify the purity of the mineral, these analyses and studies can be carried out:
- Chemical analysis is the most direct method for determining the purity of the zeolite. It involves evaluating the sample’s chemical composition. The higher the ratio of aluminum and silicon in relation to other elements, such as iron, manganese, or other unwanted minerals, the higher the purity of the zeolite.
- X-ray diffraction (XRD) is a technique used to identify and quantify crystalline phases in a zeolite sample. A high content of zeolite crystalline phases and the absence of other unwanted phases indicate high purity.
- Thermogravimetric Analysis (TGA) allows for measuring the weight loss of a specimen when gradually heated. Pure zeolite should not experience significant weight loss at low temperatures, but the presence of impurities can result in weight loss before zeolite decomposition.
- Infrared Spectroscopy (FTIR) identifies functional groups in a sample. The presence of specific functional groups can indicate organic or inorganic impurities.
- Sweep Electron Microscopy (SEM): Allows observation of zeolite morphology at a microscopic level. A pure zeolite must show uniform crystalline morphology, while impurities can manifest as inclusions or non-crystalline areas.
- Ion exchange analysis: This method involves saturating the extract with a standard solution and subsequently measuring the ion exchange capacity. A pure zeolite will have a higher ion exchange capacity, since impurities would occupy exchange sites.
- Adsorption analysis: Performing adsorption tests with known molecules can reveal the adsorption capacity of the zeolite. A pure zeolite will show a high adsorption capacity.
- Color evaluation: Although not a definitive method, the color of the zeolite can provide clues about its purity. Purer zeolites tend to be whiter or colorless, while impurities can give them a darker shade.
What applications does zeolite have?
Zeolite for water filtration
A water filter made of high-quality zeolite has a filtration area ten times larger than a conventional filter, so it retains particles between its grains and cavities, filtering particles down to one micron.
While sand and anthracite only mechanically filter between their grains, zeolite has a high electrostatic charge, which allows it to partially retain microparticles of up to one micron and colloids in its surface area. In contrast, its high electronegativity enables it to absorb ions such as iron and manganese permanently. On the other hand, this property in turn provides it with an ion exchange capacity, which allows sodium ions to be exchanged for calcium, magnesium, and ammonium ions. Learn how zeolite is applied as a filter medium in Zeomedia.
Zeolite filters for swimming pools
The zeolite retains particles of up to 3 microns, reducing the need to apply clarifiers. Likewise, it retains particles that, when reacting with chlorine, reduce its efficiency, resulting in pool filters absorbing the ammonia present in the water, preventing the formation of chloramines. Both properties contribute to saving chemical consumption by up to 25% (between biocides and clarifiers).
Zeolite for air filtration.
The zeolite molecular filters or sieves are responsible for separating oxygen from nitrogen and returning it purified to the oxygen generators so that people can breathe more purified air. Thanks to the material’s physical characteristics and high porosity, it allows it to retain particles of a fluid, depending on the size of the molecules. For oxygen concentrators, zeolite retains nitrogen particles through the micropores of this mineral, resulting in high-quality purified air.
Zeolite for human consumption.
Since its discovery, research has been done on the potential benefits of zeolite as a dietary supplement or alternative medicine in both humans and animals. The great advantage is that these natural minerals can carry out a cation exchange through their biochemical processes to capture or absorb heavy metals in the digestive system or protect humans (and animals) from mycotoxins. However, despite its broad spectrum of uses, they have not yet been fully integrated into a global market because not all of them meet the required criteria in terms of purity and pore diameter.
Zeolite for animal nutrition.
Thanks to its ion exchange capacity and microporous qualities, zeolite has been studied to improve animal nutrition, absorb toxins, eliminate bad odors, optimize yield, and improve egg quality. In addition, it is used to counteract the negative effects of mycotoxins, animal diarrhea syndromes, milk fever, and reduction of skeletal deformities.
Zeolite as fertilizer.
One of the most common problems with the use of fertilizers is their volatilization and leaching, losing up to 40% of the fertilizer applied, causing significant economic losses. In fact, the use of fertilizers with zeolite has helped prevent degradation, soil wear, as well as the loss of organic matter; problems that cause a reduction in production rates, an increase in the presence of pests and diseases related to poor crop nutrition.
Catalysis and refining.
Zeolite plays a crucial role in the petrochemical and petroleum refining industry. Its porous structure acts as a catalyst in chemical reactions, such as the conversion of heavy hydrocarbons into lighter products, thus improving the efficiency and quality of fuels and petroleum products.
Gas adsorption and separation.
Zeolite is used in gas adsorption and separation processes, such as air purification and the capture of polluting gases, including carbon dioxide (CO2). These applications are crucial in mitigating climate change and reducing greenhouse gas emissions.
Chemical industry.
Zeolite is used in the production of chemicals, as detergents, and personal care products. Its porous structure allows it to trap and release molecules, making it an efficient agent in ion exchange and adsorption processes in the manufacture of various chemicals.
Construction and advanced materials.
Zeolite also finds applications in construction. In the manufacture of high-strength cement and concrete, zeolite acts as an additive that improves the durability and thermal properties of these materials, contributing to the energy efficiency of buildings.
The quality of zeolite, determined by its purity and specific properties, is crucial to guarantee its efficiency and performance in these applications.
Where to buy zeolite?
For raw materials, water treatment, animal nutrition, and other industrial applications, you can quote the purchase of zeolite with Zeomex, the experts in this mineral.
At Zeomex, we are a company with more than 20 years of experience in the production and purification of zeolite, as well as in the manufacturing and marketing of specialized products based on this mineral.
