Let us say
we have a solution that contains a solute.
Osmosis is the process of spontaneous (net)
movement of solvent molecules (across) through a semi-permeable membrane into a
region of higher solute concentration.
Thus the solute concentration on both sides of the membrane are
attempted to be equalized.
In this process the solvent particles must
move across the semi-permeable membrane.
The solute particles do not move.
The process of Osmosis is a physical process and is dependent on the
pressures on the solutions on either side.
Finally, the process attains an equilibrium.
The permeability through the membrane depends
on the size, charge, solubility and some chemical properties of solute and
plays an important role in the biological processes in our body. Water, Oxygen, Nitrogen etc. are permeable
through biological membranes. Osmosis occurs naturally.
In this process we try to separate the solute
from solvent. We use the reverse of the
Osmosis process. We use high pressure
to force the solvent through the semi-permeable membrane to go towards the side
that contains less concentration of the solute.
The pressure exerted is more than the Osmotic pressure.
Reverse Osmosis (RO) is a well known method
or technology for purification of water to make it potable. Here the high pressure is created by a
chemical potential (with a battery).
Thus some ions, impurities including harmful bacteria are removed by
using a semi permeable membrane.
Reverse Osmosis is based on the mechanism or process of diffusion of
solvent molecules. The efficiency
process is dependent on the pressure, solute concentration and water flow rate.