The color of the distilled product is yellowish
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What is the reason for the yellow color of the product discharged from the top of the distillation tower? Conditions: The product is 1,4-butanediol; the fluid is acidic, and NaOH (0.02%) is added during flow. The temperature in the distillation tower is high (185°C at the bottom). The amount of heavy boiling components in the product is high (2%). It is normal distillation operation, and the yellow color of the product raises the question: is it necessary to analyze for iron ions?
In chemical products, the analysis of iron ions is essential; the specific testing methods can be found at the following link: http://bbs.hcbbs.com/thread-542848-1-1.html
It is necessary to analyze the iron ions; a yellow color is very likely caused by trivalent iron ions.
You might be a beginner. First, test the pH value of the finished product. If it is acidic, then there must be iron in the product; in that case, there’s no need to test for iron. There are definitely weak acids present, so investigate which weak acids are generated during the manufacturing process. Check their boiling points to see if they can be separated through distillation. If separation isn’t possible, then other methods must be considered for dealing with the azeotrope.
There are several possible reasons why the product coming out of the tower is yellow: 1. The distillation temperature may be too high, which could cause changes in the properties of the product. Since NaOH is used for neutralization, if the pH level is not properly controlled, 1,4-butanediol will react under alkaline conditions, resulting in the product turning yellow. It is best to adjust the pH value before starting the distillation process. 2. If the material of the tower top condenser is carbon steel, it will also affect the color of the product. 3. The presence of boiling points within the product indicates that the separation efficiency of the tower is low, or that the reflux rate is too low to ensure complete separation; in such cases, the number of tower plates can be increased or the reflux rate raised to make adjustments. Additionally, materials with high color intensity are generally heavy components and do not appear at the top of the tower. 4. The vacuum level can be appropriately increased, the distillation temperature can be reduced, thereby minimizing side reactions.
1. If the distillation temperature is too high, it may cause changes in the properties of the product. Since NaOH is used for neutralization, if the pH is not properly controlled, 1,4-butanediol will react under alkaline conditions, resulting in the product turning yellow. At high temperatures under acidic conditions, there are side reactions; but what kind of reactions occur under alkaline conditions? ? Please give me some advice!
Is that even necessary to ask? It’s definitely because the heavier components haven’t been vaporized. Go back and vaporize them again, increase the reflux ratio; the good product will come from the top of the tower, while the heavier components will be at the bottom of the tower!
Check the pH value, check the distillation temperature, and test for iron ions.
Before distillation, the feed solution is first passed through ion exchange resin, which removes impurities such as organic acids and inorganic salts, thus solving the problem. gfm2005@126.com
Hello, do you have a contact number? It’s 15152107003, mine
Hello, do you have a contact number? It’s 15152107003, mine