Question

What is the range of pore size of membranes that are used in reverse osmosis water purification systems found in homes?
1. 5 – 10 nm
2. 1 – 5 nm
3. 0.1 – 1 nm
4. < 01 nm

Answer 1

Correct Answer - Option 3 : 0.1 – 1 nm

The correct answer is 0.1 – 1 nm.

• Reverse osmosis filters have a pore size around 0.0001 micron (0.1 nm).
• After water passes through a reverse osmosis filter, it is essentially pure water.
• In addition to removing all organic molecules and viruses, reverse osmosis also removes most minerals that are present in the water.

• Reverse Osmosis:
  • Reverse osmosis is a special type of filtration that uses a semi-permeable, porous membrane, that allows only pure water to pass through it, filtering the larger molecules or impurities. 
  • This is used in water purification systems.
• Osmosis:
  • ​This is the process by which the molecules of a solvent pass through the semi-permeable membrane from a region of lower concentration to a higher concentration.
  • This is observed during the opening of stomata and absorption of water from the soil by the roots.