Define osmosis and reverse osmosis. Write the advantages of reverse osmosis

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Osmosis and Reverse Osmosis :-

Osmosis is defined as the process of the spontaneous flow of solvent particles through a semi-permeable membrane from a dillute solution to a concentrated solution (from lower concentration to higher concentration). The diffusion of solvent particles takes place on account of hydrostatic pressure called Osmotic Pressure, which drives solvent molecule sin search of equilibrium.

If an external pressure equal to osmotic pressure is applied on the concentrated solution, the process of the osmosis will stop and if the external pressure exceeds osmotic pressure, solvent will be squeezed out to be concentrated solution. This process is called Reverse Osmosis.

Thus in, Reverse Osmosis, pure water is separated from its contaminants rather than the removing contaminants from water. This process is also known as Super - Filtration or Hyper - Filtration.

Advantages : -

• This process removes lead, calcium, magnesium, sodium sulphate, most micro-organisms and organic chemicals from water.

Disadvantages :-

• It requires large volume of water. It may take as mush as 90 liters water to recover 5 liters of useable water.