Methods of recycling polystyrene material comprising brominated contaminants

Method of recycling a polystyrene waste,

• the method comprising:
• dissolving the polystyrene waste in a solvent mixture comprising about 50 wt % to about 90 wt % of a first solvent or a second solvent;
• and about 10 wt % to about 50 wt % of a hydrocarbon polystyrene non-solvent, to obtain a polystyrene/second solvent mixture and a solid comprising the copolymer,
• wherein the first solvent is chosen from benzenes substituted with one or two substituents each chosen from C1 and C2 alkyl, and mixtures thereof,
• wherein the second is solvent chosen from benzenes substituted with one to four, optionally one or two, substituents each chosen from C1 to C4 alkyl, wherein at least one of the one to four substituents is isopropyl,
• and wherein the hydrocarbon polystyrene non-solvent being a C5 to C8 hydrocarbon,
• separating the solid comprising the copolymer from the polystyrene/second solvent mixture,
• combining the polystyrene/second solvent mixture with a first portion of hydrocarbon polystyrene non-solvent at the boiling point of the hydrocarbon polystyrene non-solvent to obtain precipitated polystyrene and a first portion of hydrocarbon waste solution,
• separating the precipitated polystyrene from the first portion of hydrocarbon waste solution, optionally repeating the dissolving, adding and separating,
• washing the precipitated polystyrene
• with a second portion of hydrocarbon polystyrene non-solvent at the boiling point of the hydrocarbon polystyrene non-solvent or
• with a second solvent mixture comprising about 50 wt % to about 90 wt % of the hydrocarbon polystyrene non-solvent and about 10 wt % to about 50 wt % of a first solvent as defined above or the second solvent, and mixtures thereof to obtain a washed polystyrene and a second portion of hydrocarbon waste solution,
• separating the washed polystyrene from the second portion of hydrocarbon waste solution,
• washing the washed polystyrene
• with a third portion of hydrocarbon polystyrene non-solvent at the boiling point of the hydrocarbon polystyrene non-solvent or
• with a third solvent mixture comprising about 50 wt % to about 90 wt % of the hydrocarbon polystyrene non-solvent and about 10 wt % to about 50 wt % of a first solvent as defined above or the second solvent, and mixtures thereof to obtain a twice washed polystyrene and a third portion of hydrocarbon waste solution,
• separating the twice washed polystyrene from the third portion of hydrocarbon waste solution, and
• drying the twice washed polystyrene.