Method of eleminating miniature amount of impurities in epsilon-caprolactam water solution

Abstract

The present invention features that electric dialysis membrane is used to eliminate the inorganic impurities and miniature amount of organic impurities in water solution of epsilon-caprolactam, that is, water solution of epsilon-caprolactam of 5-90 wt% concentration is made to pass through electric dialysis membrane at 0-150 deg.c. The said method is used to replace ion exchange process for refining caprolactam and can reduce greatly the conductivity and extinction value of water solution of epsilon-caprolactam and eliminate ammonium radical, acid radical and other ions and miniature amount of organic impurities in water solution of epsilon-caprolactam. s

Description

Technical field [0001] The invention relates to a method for removing trace impurities in an ε-caprolactam aqueous solution, in particular to a method for removing inorganic impurities and trace organic impurities in a caprolactam aqueous solution by using an electrodialysis membrane. Background technique [0002] ε-caprolactam is the main raw material for the production of nylon-6. Industrially, in its refining and purification process, inorganic impurities and trace organic impurities in the ε-caprolactam aqueous solution are removed by the method of ion exchange resin adsorption. The limitations of this process are: ion exchange resin needs to be regenerated regularly, and regeneration is expensive; acid and alkali are required for regeneration, and there is equipment corrosion; there are problems such as caprolactam loss and a large amount of waste water with high COD content during backwashing. Therefore, for a long time, people have been looking for a new method to replace ...

AI Technical Summary

Problems solved by technology

The limitations of this process are: the ion exchange resin needs to be regularly regenerated, and the regeneration cost is expensive; acid and alkali are required for regeneration, and equipment corrosion occurs; caprolactam is lost during backwashing and a large amount of wastewater with high COD content is produced.

[0003] The concentration of caprolactam aqueous solution required for ion exchange resin adsorption has certain requirements. If the concentration is too high, it will affect the ion exchange effect, and if the concentration is too low, it will increase the operating cost.