Patent ID: 7728047

Claim:
A process for the recovery of polystyrene from a waste material comprising expanded polystyrene, said process comprising: i. reducing a volume of said expanded polystyrene by dissolution of said expanded polystyrene in a solvent, thereby obtaining a solution; ii. separating an insoluble component from said solution; iii. precipitating polystyrene from said solution by mixing an anti-solvent, to obtain precipitated polystyrene; iv. separating, washing and drying of the precipitated polystyrene; v. fractionating, by distillation, of components of a mother liquor used for the precipitation and washing, recovering of the solvent from a head of a distillation column and recycling of said solvent to step i), and recovering of the anti-solvent from a bottom of the distillation column; wherein the anti-solvent is a butanol selected from the group consisting of n-butanol, iso-butanol and sec-butanol; and wherein the solvent is dimethyl carbonate in a mixture containing up to 25% by weight of butanol, said butanol being present.