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National carrier Air India has begun the first of its “zeolite cargo flights”. This was done after the government of India started the process of importing zeolite from across the world for use in medical oxygen plants.
Zeolites in Medical Oxygen Plants:
- Zeolites are used as adsorbent material in the Pressure Swing Adsorption (PSA) process to produce medical-grade oxygen.
- How is it used? The zeolite is used as a molecular sieve to create purified oxygen from the air. This is done by using zeolite’s ability to trap impurities.
- An oxygen concentrator uses Zeolites to adsorb atmospheric nitrogen and then vents out the nitrogen. This will leave highly purified oxygen and up to 5% argon.
What is the Pressure Swing Adsorption(PSA) Process?
- It is a technology used to separate some gas species from a mixture of gases under pressure.
- Specific adsorbent materials (e.g., zeolites, activated carbon, molecular sieves, etc.) are used as a trap and adsorb the target gas at high pressure. For example, zeolite is used to separate oxygen from the air.
- The PSA process operates at near-ambient temperatures.
What are Zeolites?
- Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts.
- Zeolites have small openings of fixed size in them. This allows small molecules to pass through them easily. However, larger molecules cannot pass through them. This is why they are sometimes called molecular sieves.
- Zeolites occur naturally but are also produced industrially on a large scale.
- Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater.
- However, naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals.
- For this reason, naturally occurring zeolites are excluded from important commercial applications.
Properties of Zeolites:
- Zeolites are very stable solids that resist a variety of environmental conditions. The melting point of zeolite is very high (over 1000°C), and they don’t burn.
- They also resist high pressures.
- Moreover, they also don’t get dissolved in water or other inorganic solvents and don’t oxidize in the air.
- Since zeolites are not reactive and are obtained from naturally occurring minerals, they do not have any harmful environmental effects.
Uses of Zeolites:
- Zeolites are widely used as ion-exchange beds in domestic and commercial water purification, softening, and other applications.
- They have the potential of providing precise and specific separation of gases. This includes the removal of H2O, CO2, and SO2 from low-grade natural gas streams.
- Zeolites are also marketed as dietary supplements to treat cancer, diarrhoea, autism, herpes, and hangover. It is also used to balance pH and remove heavy metals in the body.
Source: The Hindu