Phase diagram of acetonitrile
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.