1. Electrolytic Cell + - Electric Current AnodeCathode Iron Cathode Metallic Anode Asbestos/Teflon Permeable Diaphragm Each electrolytic cell includes an iron cathode coated with an asbestos/Teflon diaphragm material and metallic anode.

2. Electrolytic Cell Diluted Brine + - Electric Current AnodeCathode Brine solution of sodium chloride dissolved in water is continuously fed to the cell and an electric charge is established between the anode and cathode

3. Electrolytic Cell 2Cl - _ > Cl 2 + 2e - 2H 2 O + 2e - _ > H 2 + 2OH - Chlorine Gas Hydrogen Gas + - Electric Current AnodeCathode The diaphragm material allows the electrolyzed brine solution to segregate and produce: Diluted Brine Cathode Compartment Hydrogen Gas Hydrogen Gas Diluted Caustic Soda Diluted Caustic Soda Anode Compartment Chlorine Gas Chlorine Gas

4. Electrolytic Cell 2Cl - _ > Cl 2 + 2e - 2H 2 O + 2e - _ > H 2 + 2OH - Chlorine Gas Hydrogen Gas + - Electric Current AnodeCathode The products of electrolysis are continuously removed from the cells and flow through downstream process equipment where the products are purified and collected Diluted Brine

5. Shutdown - Purging of Cells + - Electric Current AnodeCathode During a production shutdown the plant must purge the cells to rid them of residual chlorine and other chemicals that can corrode the cathode

6. Shutdown - Purging of Cells Alkaline Brine Sodium Bisuffite + - Electric Current AnodeCathode Standard procedure is to purge the cells with an alkaline brine solution (pH higher than to 7) including Sodium bisuffite to remove the dissolved chlorine and other corrosive chemicals present in the cell solution.

7. Shutdown - Purging of Cells Alkaline Brine Sodium Bisuffite + - Electric Current AnodeCathode When the plant was shut down on December23 and 25 there was no sodium bisulfite available. The absence of sodium bisulfite in the brine solution during these purge cycles exacerbated the rate of cathode corrosion 