What is Zeolite and Examples of Its Use?
Published On: 02-10-2023
Any member of the hydrated aluminosilicate mineral family that includes alkali and alkaline-earth metals is referred to as a zeolite. They are distinguished by ion exchange lability and reversible dehydration.
The fundamental structure is a three-dimensional tetrahedral structure made of silicon, aluminum, and oxygen atoms. When silicon is the only element present, the tetrahedron is neutral; however, when aluminum atoms are added to the silicon structure, a positive metal ion is needed to maintain the balance of charges.
A zeolite is an infinitely open, three-dimensionally structured crystalline, hydrated aluminosilicate of alkali and alkaline earth cations. Reversible water gain and loss are possible, and exchanging extraframework cations is possible without altering the crystal structure.
Additionally, it has the capacity to adsorb dissolved pollutants like heavy metals from water. It is used to remove a variety of contaminants from wastewater.
Small molecules can easily pass through zeolites because their pores are smaller than the size of organic molecule particles, but larger molecules cannot. They are sometimes referred to as molecular sieves for this reason.
Natural minerals called zeolites are found in the earth. They can be found all over the world, in many different locations. They can be mined and extracted for use, or they can be converted into artificial zeolites.
Zeolites are crystalline solids made of an aluminosilicate framework with tetrahedrally coordinated silicon and aluminum cations. Four oxygen anions surround these cations (O2-).
In this system, open cavities in the form of channels and cages can be created, allowing for the insertion and exchange of water molecules and exchangeable extra-framework cations. They can also be utilized as gas adsorbents.
Although synthetic zeolites are also available, natural zeolites are more common. Alumina and silica are just two of the many elements used to create synthetic zeolites.
They are effective detoxifiers that stop a lot of dangerous toxins from entering the body. They also promote healthy liver function and aid in reducing inflammation, which can cause serious health problems like autoimmune diseases, fatigue, depression, and other mental and physical ailments.
Zeolites are frequently used in the filtration, treatment, and separation of water. Turbidity, hydrocarbons, ammonia, nitrates, phosphates, oils, and other pollutants can all be effectively removed from wastewater using them.
Zeolite's pore structure enables it to function as a molecular sieve that separates molecules according to their size. Calcium, sodium, and potassium are all bound by the negatively charged surface.
To improve some zeolites' ability to adsorb different pollutants, acids can also be used to modify them. Results may vary depending on the reagents' types and concentrations.
Given that they can remove chromium, turbidity, and other contaminants from water, natural zeolites are also being investigated for their biological properties. In drought-prone areas, they can also serve as soil amendments for turf farms and golf courses to retain water and nutrients.
Since 1950, synthetic zeolites have been widely used to enhance insulated windows, car air conditioners, refrigerators, truck air brakes, laundry detergents, and other products. They can be easily customized to the desired properties and applications thanks to their sizeable internal pore volumes, molecular-size pores, and stable crystal structures.
In order to produce zeolite with a low CO2 footprint per kilogram, reducing the energy consumption of the manufacturing process is a significant challenge. There are currently several methods being developed and used to lower the energy requirements of synthesis gels.
A synthesis gel's solid content can be increased, the feeding slurry can be changed, heat recovery can be added during the drying process, and electrical heating can be used during calcination to reduce energy usage overall. Belt calciners or rotary kilns are frequently used for calcination under oxidizing conditions. Due to lower firing temperatures and lower emissions from the exhaust gas after-treatment system, this method also results in significant energy savings.