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I’m about to start working on electrolysis, and I’d like to learn about the process of ion membrane electrolysis first. Does anyone who is an expert in this area know how to explain it?
Water knows all the data related to the bipolar natural circulation ion membrane electrolyzer. Could you tell me? Thank you very much
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For example, the process flow for producing NaOH solution, Cl2, and H2 using ion exchange membrane technology is shown in the figure. The ion exchange membrane method has high requirements regarding the quality of saltwater; therefore, in addition to a preliminary purification step (which is the same as that used in the membrane-based saltwater purification method), a second purification step involving filtration and adsorption using chelating resins is also required, in order to keep the levels of metal ions such as Ca2+ and Mg2+ below 0.05×10-6 ; Suspended solids content is less than 1×10-6 ; The SO42- content is less than 4–5 g/L ; The free chlorine content is less than 0.1×10-6. The presence of suspended particles in saltwater can increase the resistance of the membrane. Metal ions such as Ca2+ and Mg2+ can produce hydroxides within the membrane and accumulate there, causing the ion exchange function to fail, increasing resistance, and reducing current efficiency. Due to the presence of free chlorine, it not only corrodes equipment and pipelines but also causes environmental pollution ; ClO- also has an adverse effect by hindering the aggregation and sedimentation of Mg(OH)2 and CaCO3 ; If ClO- discharges, it will inevitably lead to a decrease in current efficiency. In summary, it is highly necessary to carry out secondary purification of saltwater and to strictly control it in accordance with the quality requirements for the purified saltwater. After the anode solution (brackish water) coming out of the electrolyzer is separated from Cl2, a portion of it (about 1/10) is sent back to the electrolyzer after chlorate has been removed ; Most of the dechlorinated brine is sent to a single purification process for resaturation. After the catholyte flowing out of the tank is separated from H2, its caustic soda concentration exceeds 30%. It can be used directly as high-purity caustic soda ; Evaporative concentration can also be carried out as needed. An evaporation step is included in the process to produce 48% liquid caustic soda. A portion of the catholyte, after being replenished with deionized water, is circulated back to the cathode chamber of the electrolyzer. The circulation of the cathode alkaline solution helps to control the amount of water added, and it also removes some of the heat generated in the cell, which is beneficial for maintaining thermal balance within the electrolyzer.