What is the Difference Between Mercury Cell and Diaphragm Cell?

The main difference between a mercury cell and a diaphragm cell lies in their electrode materials, energy requirements, and environmental impact. Both cell types are used in the industrial electrolysis of sodium chloride solution to produce chlorine, sodium hydroxide, and hydrogen. Here are the key differences between the two:

• Electrode Materials: A mercury cell typically has a zinc anode and a cathode made of either pure mercury(II) oxide or a mixture of mercury and sodium amalgam. In contrast, a diaphragm cell has a titanium anode and a steel cathode.
• Energy Requirements: A mercury cell needs a higher voltage (4.5 V) compared to a diaphragm cell (3.5 V). Additionally, a mercury cell requires more electrical energy, needing 3400 kWh/ton Cl2, while a diaphragm cell requires 2500 kWh/ton Cl2.
• Environmental Impact: Mercury cells have the potential to cause environmental damage due to mercury deposits, although modern processes have significantly reduced the amount of mercury released. Diaphragm cells, on the other hand, do not have this issue.

In summary, while both mercury cells and diaphragm cells are used in the production of chlorine, sodium hydroxide, and hydrogen, they differ in their electrode materials, energy requirements, and environmental impact. Diaphragm cells tend to be more energy-efficient and environmentally friendly, making them a more popular choice for industrial electrolysis processes.

Comparative Table: Mercury Cell vs Diaphragm Cell

Here is a table comparing the differences between Mercury Cell and Diaphragm Cell:

Key differences between Mercury Cell and Diaphragm Cell are:

• Mercury Cell requires a higher voltage and more energy than Diaphragm Cell.
• Mercury Cell has a Zinc Anode and a Cathode made of either Pure Mercury(II) Oxide or Mercury Amalgam, while Diaphragm Cell has a Titanium Anode and a Steel Cathode.
• Mercury Cell can potentially cause environmental damage due to mercury deposits, while Diaphragm Cell can be a source of pollution from asbestos fibers.
• Caustic Soda produced in Mercury Cell requires further purification for some industrial uses, while Diaphragm Cell requires several concentrative operations to achieve the purity needed for industrial use.