How to understand "high concentration of acetic acid in the distillation tower will corrode the battery anode"?

This description is indeed somewhat inaccurate. In fact, if the concentration of acetic acid in the kettle in the distillation tower is high, the metal materials on the inner wall of the kettle will be corroded. This is because acetic acid has certain corrosive properties. But this corrosion process does not involve a battery reaction, and there is no distinction between anode and cathode. If you want to connect this phenomenon with electrochemistry, you can understand it like this: High concentrations of acetic acid corrode metal surfaces, forming a layer of oxide or acetate. The formation of this layer of oxide or acetate causes the local potential inside the tank to decrease, allowing other uncorroded metal areas to become more active anodes, causing the battery reaction. In this way, high concentration of acetic acid does correspond to a smaller potential, but it is not the "anode" of the battery itself, but is only one of the causes of the battery reaction. .

Thanks for clarifying! I have three further questions, please continue to clarify them.: First, my understanding: Corrosion on the metal surface forms a layer of oxide or acetate, which should increase the potential of the metal surface (rather than decrease it) so that the uncorroded area becomes an anode (corresponding to the low potential of the corroded area). Is this correct? Second, based on the understanding of the above one, is there still a problem according to the meaning of the literature "treating the top of the tower (cathode) and the tower still (anode) as a large battery" (because the potential of the uncorroded area of ​​the tower still has not changed, but the potential of the corroded area has increased, and the uncorroded area can only be regarded as an anode for the tower still)? Third, based on the understanding of the above one, can we explain the cause of corrosion near the feeding port in the original document? The uncorroded area of ​​the feeding port becomes an anode due to the increase in the potential of the corroded area (the two areas form a corrosion battery), further promoting the progress of corrosion (in the uncorroded area)?

Thank you very much for your questions. I will answer them one by one.: 1. Regarding the changes in potential after corrosion of metal surfaces to form oxides or acetates: During the corrosion process, the metal surface will continue to lose electrons, causing the potential to increase (that is, the electrode potential becomes more positive) until a certain stable state is reached. However, it should be noted here that the metal surface and the uncorroded area are not actually a completely isolated system. In addition to the migration of metal ions caused by chemical reactions, there are also some disturbance factors, such as local electric field, temperature, stirring, etc. in the flowing liquid. These factors may cause a slight difference in potential between the metal surface and the surrounding area, causing the flow of charge. If the difference is large enough, it's possible that the system constitutes a small corrosion battery, in which the metal surface is the anode and the surrounding area is the cathode. 2. Regarding the problem of treating the tower top and tower kettle as a large battery: This statement is indeed somewhat simplified. As for the potential difference between the tower top and the tower kettle, it is not only affected by the tower kettle alone, but may also be interfered by other factors, such as liquid level, flow rate, etc. However, this example mentioned in the literature is mainly to explain the relationship between the corrosion process and the electrochemical reaction, so it is only a convenient description to regard the tower top and the tower still as "a big battery". 3. Regarding the corrosion problem near the feeding port: Your understanding is correct. Since there is an uncorroded area near the feed port, it may become the "anode" in the entire system, thereby promoting corrosion in the surrounding area. Of course, corrosion near the feed port may also be affected by other factors, such as local temperature, fluid dynamics, etc. Hopefully these explanations will help you understand the problem better. If you have any other questions or doubts, please continue to ask! .

Thanks for clarifying my doubts again, and I have a deeper understanding of corrosion electrochemistry. I am digesting it. If you have any questions in the future, please ask me: lol