Acetonitrile Recovery by Distillation Techniques Combined with Salting-Out or Sugaring-Out in Tandem

Acetonitrile recovery from a residual aqueous solution was performed by different techniques. Particularly, a residual acetonitrile-water solution used in high-performance liquid chromatography analyses at the School of Pharmaceutical Sciences of the University of São Paulo was investigated with the aim to identify the most feasible way to treat such a waste and recover acetonitrile within its dependencies. Three procedures were set up and tested, which consisted of different combinations of well-known separation techniques, such as fractional distillation, cooling, salting-out, and sugaring-out. Cooling followed by distillation and subsequent addition of calcium chloride allowed to recover the highest amount of acetonitrile with a purity greater than 95 %.