How to choose an azeotrope?
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The company’s production process generates a type of wastewater: containing 5.4% ethylene glycol, 2.7% ethylene glycol ether, and 92% water. For environmental reasons, we need to evaporate the water from this wastewater, and then recover ethylene glycol and ethylene glycol ether (which also constitutes a form of recycling and helps reduce costs). The boiling point of ethylene glycol is 193°C, while the boiling point of ethylene glycol ether is 135°C. When we distill this wastewater in the laboratory, the COD level of the resulting water is too high; this is definitely because ethylene glycol ether has been carried over. Therefore, we consider using azeotropic distillation to remove water, with ethylene glycol and ethylene glycol ether remaining at the bottom of the tower; after stratification of the condensate at the top, the COD level remains below 10,000. I tried benzene and methyl isobutyl as well. But the results were all unsatisfactory. I’d like to ask the forum members for their recommendations – do you have any suggestions? Or tell me how to find a suitable azeotrope, so I can compare and search on my own. Thank you!
The main issue to address is that ethylene glycol ether cannot be separated; ethylene glycol is azeotropic with water, so it does not emerge during low-temperature distillation.
Will the azeotrope agent azeotropically remove ethylene glycol?
First, an azeotrope that is not azeotropic with ethylene glycol must be selected.
The first thing to choose is an azeotrope that will not form an azeotrope with either ethylene glycol or ethylene glycol ether: D
Azeotropic distillation **Selection of boiling agents http://wenku.baidu.com/link?url=VsdGhLb8nWIQvfn2LbBC_bKG7gkwCnzQ6lbdDxlE6HcLsdcoo-WC8J4darhDrRemFmWQZ8tmaMnP5ba_Eg6Xa3XZ7TnvgFKwlMVOP_67ELy
Since a co-azeotrope (a third component) is used, ethylene glycol (from the system) can be considered as an extractant for extraction distillation dehydration
What is ethylene glycol used to extract? Use ethylene glycol to retain ethylene glycol ether at the bottom of the tower? It’s likely impossible to achieve; ethylene glycol ether will definitely go out together with water.
May I ask: what is the maximum allowable concentration in ppm of ethylene glycol and ethylene glycol ether in wastewater as required by the Environmental Protection Agency?