Removal of Nitric Acid from Aldehyde
In the production of an aldehyde, nitric acid must be removed before further processing. Two EUR20-720 stacks, have been in operation for several years to remove 90 % of the nitric acid. Both loops are operating in an automatic batch mode. Typical membrane life is four years. Overall the customer has been very satisfied with the automatic operation of the plant, requiring very little maintenance and supervision.
Organic Salt Recovery and Purification
A pharmaceutical group produces penicillin, in their process and organic salt stream is generated after liquid/liquid extraction containing many impurities. Electrodialysis is a very effective process to remove and purify such a salt so that it can by recycled in the process : in this case, the "concentrate" is the valuable product. In 1997, 4 EUR40-350 stacks, have been installed to achieve a recovery of 90 %. This is also an automatic batch operation. Overall, the plant performance has been very satisfactory.
Desalting of Amino Acid Solution
Produced by hydrolysis of chicken feathers, a mixture of salts of amino acids contains a large amount of sodium chloride that must be removed for commercialisation. Electrodialysis is the appropriate technology to desalt this product. In 1992, six EUR20-460 stacks were started-up and six supplemental EUR20-460 were added one year later. This feed contains many organic impurities : at the end of each 20 hour batch, the membranes are cleaned by current reversal supplemented with chemical cleaning using dilute HCl and NaOH; These stacks allow a desalting rate of 90 % with high concentrated brine over 20 %.
The operation is also an automatic batch. This system is successfully running with a membrane life that has reached 12,000 hours.
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