Different solvents were tested for chemical recycling of mixed E&E waste showing recovery of polymers and removal of FRs. Mixed, shredded E&E plastic waste was provided by a commercial waste recycler in the USA, after mill beating and metal separation. This waste contained 6 – 12% phosphorus (P) and 1 – 6% bromine (Br), presumed to be in flame retardants. Eleven different solvents were tested for polymer dissolution, then dichloromethane (DCM), tetrahydrofuran (THF), methanol (MeOH) and ethylene glycol (EG) selected for further testing. Various anti-solvents were tested to precipitate and recover the polymers from solution. Depending on polymer and on the solvents/anti-solvent combinations, up to 99% of polymer was recovered from the wastes. The optimum solvent/antisolvent combination (methanol / ethylene glycol) removed up to 94% of phosphorus flame retardants (based on measurement of phosphorus contents), resulting in low levels in the recovered polymer, whereas removal of brominated FRs was ineffective, leaving 3 – 4% bromine in the recovered polymer.
“Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing”, L. Anderson et al., Processes 2022, 10, 66. https://doi.org/10.3390/pr10010066