Manufacturing of caustic soda by membrane cell

Membrane cell

1. Unit Process & Chemical Technology Sub. Code:- 3140508 TERM PAPER Topic :- manufacturing of caustic soda and cl2 by membrane cell Chemical Engineering Department 4 th sem

2. Production Process of Caustic Soda and Chlorine by Electrolysis What is electrolysis? Process of breaking down a compound into its constituent elements by passing electricity through it. Basically chlorine and caustic soda is produced by electrolysis of salt water (brine). In this process there are two types of electrolytic cell: *Diaphragm cell. * Membrane cell

3. Membrane Cell Process

4. Membrane Cell Process Reaction:- Anode: 2 Cl - → Cl₂ + 2e - Cathode : 2Na+ + 2 H2O + 2e- → H₂ + 2Na+ + 2OH- . Overall :2Na+ + 2Cl- + 2H2O → 2NaOH + Cl2 + H2

5. Membrane Cell Process This technology uses water-impermeable ion-conducting membrane. The membrane is made of a special resin which permits cations (positive ions) to pass through. The anode chamber of a membrane electrolytic cell is filled with brine, and the cathode chamber with water. The brine in the anode chamber contains sodium (Na+) and chloride (Cl-) ions.

6. Membrane Cell Process Electric current flowing through the cell decomposes the brine passing through the narrow space between the electrodes, liberating chlorine gas (Cl2) at the anode and metallic sodium (Na) at the cathode. The chlorine gas is accumulated above the anode assembly and discharged to the purification process. As it is liberated at the surface of the mercury cathode and the sodium immediately forms an amalgam (a ‘mixture’ of two metals)

7. The chlorine is washed and cooled to remove salt, and further dehydrated before being delivered or liquefied. Chlorine is liquefied and stored low temperature. The liquid chlorine from the bulk tank can be used as a feedstock.

8. Caustic soda is further concentrated in a vaporizer to a concentration of about 50% for delivery.

9. Membrane Cell is Widely Used It never gets contaminated with any sodium chloride solution due to presence of water-impermeable ion-conducting membrane. The caustic soda is more quality. Operates at low voltage. Energy efficient. Less environmental impact

10. Membrane Cell Process Advantages Low energy consumption. Low capital investment. High purity caustic. Insensitivity to cell load variations and shutdowns. Disadvantage Cost of membrane. Use of solid salt, high purity brine. High oxygen content in chlorine.

11. THANK YOU EVERYONE Nirav Bhutaiya (230313105003)