From UPSC perspective, the following things are important :
Prelims level : Zeolite
Mains level : NA
To meet the demand of oxygen supply in the country during the peak of pandemic, the Defence Research and Development Organisation (DRDO) had chartered the Air India to import ‘Zeolite’ from different countries.
What are Zeolites?
- Zeolites are highly porous, 3-dimensional meshes of silica and alumina.
- In nature, they occur where volcanic outflows have met water.
- Synthetic zeolites have proven to be a big and low-cost boon.
Uses in Oxygen Concentrator
- One biomedical device that has entered our lexicon during the pandemic is the oxygen concentrator.
- This device has brought down the scale of oxygen purification from industrial-size plants to the volumes needed for a single person.
- At the heart of this technology are synthetic frameworks of silica and alumina with nanometer-sized pores that are rigid and inflexible.
- Beads of one such material, zeolite 13X, about a millimeter in diameter, are packed into two cylindrical columns in an oxygen concentrator.
How does it work?
- Zeolite performs the chemistry of separating oxygen from nitrogen in air.
- Being highly porous, zeolite beads have a surface area of about 500 square meters per gram.
- At high pressures in the column, nitrogen is in a tight embrace, chemically speaking, with the zeolite.
- Interaction between the negatively charged zeolite and the asymmetric nucleus (quadrupole moment) of nitrogen causes it to be preferentially adsorbed on the surface of the zeolite.
- Oxygen remains free, and is thus enriched.
- Once nitrogen is captured, what flows out from the column is 90%-plus oxygen.
- After this, lowering the pressure in the column releases the nitrogen, which is flushed out, and the cycle is repeated with fresh air.