ContextÂ
- Â In India, IISc has transferred the technology of making Zeolite oxygen concentrators to over 20 companies.
About ZeolitesÂ
- Zeolites are highly porous, 3-D meshes of silica and alumina.
- They occur naturally and are also produced industrially on a large scale.Â
- Â In nature, they occur where volcanic outflows have met water.Â
- Synthetic zeolites have proven to be a big and low-cost boon.Â
- They are often also referred to as molecular sieves.
- The zeolites are noted for their lability toward ion exchange and reversible dehydration.Â
- They have a framework structure that encloses interconnected cavities occupied by large metal cations (positively charged ions) and water molecules.
Zeolite oxygen concentrators
- One biomedical device that has entered our lexicon during the pandemic is the oxygen concentrator.Â
- This device has brought down the scale of oxygen purification from industrial-size plants to the volumes needed for a single person.Â
- At the heart of this technology are synthetic frameworks of silica and alumina with nanometer-sized pores that are rigid and inflexible.Â
- Beads of one such material, zeolite 13X, about a millimetre 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 the air.
- Being highly porous, zeolite beads have a surface area of about 500 square meters per gram.Â
- At high pressures in the column, nitrogen is in a tight embrace, chemically speaking, with the zeolite.Â
- 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.Â
- Â Once nitrogen is under arrest, what flows out from the column is 90%-plus oxygen.Â
- After this, lowering the pressure in the column releases the nitrogen, which is flushed out, and the cycle is repeated with fresh air.
Source: TH
