(57t) Use of Electrochemical Processes to Regenerate Sodium Hydroxide From Brine

A lab scale chlor-alkali system was designed in order to demonstrate the feasibility of the process for recycling a scrubber product brine solution to regenerate caustic for the Johnson Matthey company. An additional goal was to optimize the technology for use with this solution. An electrolytic cell containing a Nafion 324 membrane, a RuO2 based coating on Ti substrate cathode, a Steel or Ni based catalytic coating on Ni anode, tubing, and components resistant to corrosion were purchased. From the laboratory studies using this cell it was determined that the spent scrubber fluid can be economically converted to NaOH. Additionally, the optimum temperature for this process was found to be 90°C. The efficiency, based on the amount of electrical energy input into the cell electrodes, is 85% at room temperature (20°C) and is a maximum of 95% at 90°C. From the experiments performed it was determined that an electrode area of 100cm2 was able to produce NaOH at a rate of 0.1422 mol/h. Scaling this to the JMI processing requirements to produce the 800 gallons of NaOH at a 15%w with the spent scrubber solution treatment requires a system with an electrode area of 64m2. This system has a capital cost of approximately $631,462 with an estimated payback period of 3.86 years.