Wednesday, September 18, 2013

Heavy Water ( Preparation - Electrolytic cell Method )

Heavy Water:

  • Heavy water is also called as deuterium oxide or 2H2O or D2O. 
  • The oxide of hydrogen is called heavy water.
  • Heavy water was discovered by Urey in 1932.
  • Heavy water occurs naturally, although it is much less common than regular water.
Preparation of heavy water :

             The main source of heavy water is the ordinary water from which it is isolated. Generally it is prepared by prolonged electrolysis or fractional distillation.

Prolonged Electrolysis Of Ordinary Water:
            This method is involved in multistage electrolysis of ordinary water containing alkali. ( eg. NaOH ). The cylindrical vessels made of steel which act as cathode. The cylindrical sheet of nickel which act as anode with a number of holes punched in it. The electrolysis carried out in different stages. In these stage large number of electrolytic cells are used.

First Stage:
      Thirty electrolytic cells are used in this stage. Each cell is filled with 3% of NaOH solution. The electrolysis is carried out at 72-hrs, in the presence of current at 110 volts.The volume is reduced to 1/6 th of original volume taken.That tome hydrogen and oxygen gases are evolved and discarded. The volume left contains about 2.5 % of heavy water.
Second Stage:
       In this stage 6 electrolytic cells are used. This stage involves the residue left from the first stage. The gases evolved are burnt and water formed return to the first stage cell. The residual liquids contain 12% of heavy water.
Third Stage:
       This stage involve the residue left from the second stage. The gases are burnt and water formed return to the second stage cell. The content of heavy water is raised to about 60%.
Fourth Stage:
       This stage involve the residue left from the third stage. The gases are evolved are burnt as usual and sent to third stage cell. Here nearly 99% of heavy water is obtained.
Fifth Stage:
        99% of heavy water is made free from alkali and other impurities by distillation. Here the gases evolved are  D2  and   O2  are burnt to get 100% pure heavy water.

1 comment:

  1. Hi.
    What is de Volume that he used in 3° stage and 4° stage?
    The 1° --> 2° used 1/6 of original volum
    2° ---> 3° = Vol?
    3° --> 4° = Vol?
    4° --> 5° = Vol?