Crystallization recovers and upgrades the quality of Acetonitrile
The growth in consumption of acetonitrile as HPLC solvent and reagent in
pharmaceutical synthesis has not only increased the demand for this chemical
but also the need for disposal of the spent solvent.
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The
smallest amount of impurities can significantly affect the quality of the final
products. Therefore, ultra-pure starting materials are essential. Most of the
acetonitrile produced today comes as a by-product from the production of
acrylonitrile. Another significant source of this product can be found in the
waste of universities, research labs and pharmaceutical production facilities.
These streams, although generally quite pure, are still considered hazardous
waste and are bound for incineration
in licensed disposal centers.
Crystallization can provide these locations with a cost efficient method to
recover this product as ultra-pure acetonitrile.
A waste stream of
relatively pure feed stock with between 98wt% and 99wt% acetonitrile can easily
be upgraded to product around 99.99wt% (the highest purity available) with
suspension crystallization. This method offers an efficient means to reduce
waste disposal costs and provides a valuable product since commercially
available HPLC grade acetonitrile sells for Euro 20-30 per liter.
The
solid-liquid phase diagram for a solution of acetonitrile and water is shown
below. Unlike distillation techniques, suspension crystallization provides the
possibility to separate ultra-pure acetonitrile crystals in a single step.
Crystallization is a proven industrial purification technique and GEA
Niro PT has been active in its application on a variety of products for over 30
years. Acetonitrile purification is just one of our new applications.