Salt purifies air primarily by attracting and capturing water vapor which carries airborne pollutants.
Understanding the mechanism behind how salt is thought to purify air revolves around its unique property known as hygroscopy. This characteristic allows certain types of salt, like the Himalayan pink salt used in salt lamps, to interact directly with moisture in the surrounding air.
The Role of Hygroscopic Properties
Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment through either absorption or adsorption. Salt is a well-known hygroscopic material.
- Attracting Water Vapor: Hygroscopic salt surfaces draw moisture from the air.
- Capturing Pollutants: Airborne pollutants, such as dust, pollen, and mold spores, often attach themselves to water molecules suspended in the air.
- Removing Pollutants: When the salt attracts the water vapor, they attract and capture water vapor along with the pollutants it's carrying from the air. This process effectively removes these particles from the air circulating around the salt.
Essentially, the salt acts like a magnet for water vapor, and since pollutants are piggybacking on this vapor, they get trapped on the salt surface as well.
The Process in Action
Here's a simplified breakdown of how this process works:
- Humid air containing microscopic pollutants passes by a hygroscopic salt surface (like a salt lamp).
- The salt attracts the water vapor from the air.
- Pollutants attached to the water vapor are also drawn to the salt surface.
- The water and the captured pollutants condense or stick onto the salt.
- This removes the water and pollutants from the ambient air.
When the salt warms up (as in a heated salt lamp), the trapped water may evaporate back into the air, but the captured pollutants are intended to remain trapped on the salt surface.
This mechanism suggests that salt can help reduce the concentration of certain airborne particles by binding them to its surface via moisture interaction.
