Preparation of Heavy Water

 Heavy water is a form of water with a deuterium composition. The number of neutrons in hydrogen, deuterium, and tritium is 1, 2, and 3 respectively. This change in the number of neutrons will change the properties of that element. Heavy water is prepared by multiple electrolysis of water.

Other methods of preparation include the girdler sulphide process and fractional distillation. Heavy water has a wide range of uses in medicine, biology, and business. For example, heavy water is used as a moderator in nuclear power reactors. 

Heavy water will increase the thermostability of macromolecules. Vaccines need this feature to preserve their thermostability. Malignant cells are more affected by heavy water than normal ones. Deuterated anti-cancer medications are known to have fewer adverse effects.

Methods of preparation- Meaning

Heavy water is mainly prepared using normal water by prolonged electrolysis. The prolonged electrolysis separates deuterium from water. Separated deuterium from normal water is treated with oxygen to form heavy water.

• By Multiple stages of electrolysis (prolonged electrolysis)

This is an exhaustive electrolytic process. As we know, there are more normal hydrogen atoms in water than deuterium. When we electrolyse, protium is liberated. While we continue to electrolyse further, the concentration of protium gets reduced to an extent where the concentration of deuterium is more.

The electrolytic cell had many designs throughout the time. The cathode for the electrolysis is the electrolytic cell itself. A cylindrical Ni sheet with holes acts as an anode.

• Fractional distillation

Heavy water has different properties than ordinary water due to a change in the number of neutrons. The fractional distillation utilises this property. A 12-metre long fractionating column is used for this. When the vapour ascends and passes through the fractional column, only the volatile component is in this case.

This is how heavy water is prepared using fractional distillation

• Girdler sulphide process

The Girdler sulphide procedure is a method that relies on a deuterium transfer between H2S and ordinary light water. There are two distinct columns in this operation. One column is 30°C and is called the “cold tower,” while the other is 130°C, called the “hot tower.” The separation occurs from the differences in equilibrium between the two temperatures.

Uses of heavy water

• A neutron moderator in nuclear reactors
• The heavy water-moderated reactors form tritium
• Preparation of deuterium by electrolysis
• Used as a tracer compound to study the various reaction mechanism
• To label hydrogen in organic chemistry.
• Used in Fourier Transform Infrared spectroscopy
• Used in nuclear magnetic resonance.
• Therapeutic purpose with anticancer drugs

Conclusion

Heavy water is another form of water having deuterium in composition instead of protium (single H atom). Heavy water is mainly prepared using normal water by prolonged electrolysis. The prolonged electrolysis separates deuterium from water. 

Separated deuterium from normal water is treated with oxygen to form heavy water. There are also other methods of preparation. Let’s move on to the preparation of heavy water. When we electrolyse, protium gets liberated. While we continue to electrolyse further, the concentration of protium is reduced to an extent where the concentration of deuterium is more. Therefore, the boiling point of heavy water is slightly higher than that of normal water. The fractional distillation utilises this property. A 12-metre long fractionating column is used for this. When the vapour ascends and passes through the fractional column, only the volatile component finally remains, which is the deuterium in this case. The Girdler sulphide procedure is a method that relies on a deuterium transfer between H2S and ordinary light water.

 Heavy water has several advantages such as: 

• A neutron moderator in nuclear reactors
• The heavy water-moderated reactors form tritium
• Preparation of deuterium by electrolysis
• Used as a tracer compound to study various reaction mechanisms
• To label hydrogen in organic chemistry
• Used in Fourier Transform Infrared spectroscopy
•  Used in nuclear magnetic resonance and Therapeutic purpose with anticancer drugs.