What is a good method for solvent dehydration?
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During our production process, a large amount of solvents is reused, but the water content in these solvents is 0.25%; it needs to be reduced to below 0.1%. Do any of you have any good solutions? The solvent is mainly dichloroethane, with a pH of around 2, and contains a high amount of chloride ions. I have seen methods using molecular sieves for dehydration; I’m not sure if this approach works, and which type of molecular sieve would be suitable?
Dichloroethane? What substances cause acidity? Simply removing water from dichloroethane is quite convenient; if there are other components involved, it’s better to specify them all. This shouldn’t involve any confidentiality issues
It is mainly acidic due to hydrochloric acid; of course, there are some other substances present as well, but they have no impact – hydrochloric acid alone is sufficient to consider
Theoretically, acid-resistant molecular sieves can be used, but some of the main component will also be lost. More effective methods require further research
Then removing water becomes much simpler: 1. After neutralization, it’s also possible to skip neutralization and achieve water separation through distillation (this is a relatively primitive method)； 2. After neutralization, water is removed using a gas pervaporation membrane.
Forgot to mention one more thing: carefully study the components of the solvents. A small amount of certain components can have an impact on the process parameters. There’s no need to keep everything secret; most companies in China don’t have anything that truly requires secrecy when it comes to individual components. If secrecy is necessary, then it should apply to the entire system as a whole.
Thanks for the advice! The main substance doesn’t matter; this only has requirements regarding the water content
1. Distillation for water removal: Removing that small amount of water by distilling would require evaporating most of the dichloroethane, which is not worth it; moreover, the results may not be good； 2. Neutralization: The purpose is purification; introducing new impurities is discouraged ； 3. Confidentiality: Sufficient conditions have been provided; other details are omitted to avoid confusion and unnecessary hassle ； 4. Observe more, speak less
I hope you are only involved in research and development; if you work in engineering, well… . . . . . .