The effect of iron ions in secondary brine on electrolyzers and membranes
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This post was last edited by sunjl1981 on 2013-1-6 20:07. As the title suggests: If the secondary brine that has been treated with chelating resin contains high levels of iron, what impact does this have on the subsequent electrolyzers and membranes? If the iron ion concentration in the crude salt is between 300-500 PPb, what methods can be used to reduce it before it enters the resin column? This post was last edited by yzhms on 2009-3-14 11:30 ] # ， ， &
Iron-containing metal ions will permeate from the cathode chamber to the anode chamber, where they react with OH- to form hydroxide precipitates within the exchange membrane. This not only leads to an increase in cell voltage and a decrease in current efficiency, but it also creates micropores that cause physical damage and fragmentation of the polymer structure, resulting in irreversible damage to the membrane.
What are the acceptable parameters for the secondary brine effluent to avoid causing excessive stress on the membrane? Is it 20 PPb or lower? This post was last edited by yzhms on 2009-3-14 10:50]
The key to ferric ions in secondary brine lies not in the process but in testing. If you don’t know the exact amount of iron ions, how can you control it properly? See http://bbs.hcbbs.com/forum-224-1.html
The original poster can take a look at the relevant forum posts: http://bbs.hcbbs.com/viewthread.php?tid=179328&highlight=%CC%FA http://bbs.hcbbs.com/viewthread.php?tid=85650&highlight=%CC% http://bbs.hcbbs.com/viewthread.php?tid=179328&highlight=%CC%FA
1. The resin tower has a limited capacity for treating iron, as it is primarily effective in dealing with divalent metal ions； 2. May I ask what the iron content in the water produced by the original poster is? 3. Excess iron levels are generally not caused by ferric chloride; similarly, they are not resulting from a high iron content in the raw salt. And what is the iron content in salt anyway? 4. The control of iron mainly depends on the treatment process with saltwater, but the impact of anti-caking agents is another matter; you can refer to the recommended post above ； 5. The impact of iron on the membrane is limited, but in the presence of acid it must be kept below 50 PPb; under acidic conditions, the pH distribution within the electrolyzer and the membrane changes, allowing iron to penetrate into the membrane ； 6. A large amount of iron will form oxides, which cover and affect the active coating on the anode; however, the situation improves after rinsing. The points mentioned above are for reference and discussion only; they are based on the recommendation post from above and have been further analyzed, in the hope of being helpful to the original poster.
It has little impact on the electrolyzer; the main effect is on the ion membrane, which reduces current efficiency. It’s better to be careful.
1. If the excess amount of alkali in the primary brine with two alkalis is kept within the specified range, the iron content in the primary brine generally will not exceed 100 ppb. In China, many primary brine systems use carbon steel pipes, and no cases of excessive iron content have been detected. 2. If the iron content in the secondary brine is above the acceptable level, it is necessary to pay sufficient attention: it is generally believed that the adsorption of iron by chelating resins is irreversible, meaning permanent poisoning occurs ； High iron content severely affects the service life of ion exchange membranes and increases power consumption. At this time, it is necessary to check whether the rubber lining of the resin tower and those of the supply pipes for primary and secondary brine have come loose. This post was last edited by Qicai Shuizhizi on 2009-3-18 17:41.]