Reverse osmosis

Osmosis is a phenomenon which regulates many biological functions in plants and animals. That the plants stand upright, or the water reaches the tip of every leaf of a plant is due to osmotic pressure. The fact that we cannot survive by drinking seawater is also linked to this same phenomenon. J H van’t Hoff showed in 1886 that osmotic pressure is related to concentration and temperature of the solution by a law that is similar to the gas law. An understanding of this phenomenon paved the way not only in explaining the biological functions which depend on osmosis, but also in creating conditions for reversing it known as ‘reverse osmosis’. Reverse osmosis has many applications, one of which is desalination of seawater. The inaugural Nobel Prize in Chemistry was awarded in 1901 to van’t Hoff for his seminal work in this area. The present article explains the principle of osmosis and reverse osmosis.