Solvent is shown to dissolve the phosphorus FR BDP from PC/ABS, enabling recovery of the PIN FR for recycling. The solvent N, N-dimethylcyclohexylamine (DMCHA) was used because of its switchable hydrophilicity. Powdered commercial FR PC/ABS resin (containing the phosphorus PIN FR bisphenol-A bis(diphenyl phosphate) (RDP) was stirred in DMCHA for 3 hours at 70°C. The RDP dissolves in and then reacts with the solvent. The RDP can be recovered by mixing the solvent with water and bubbling through CO2, resulting in separation, and the solvent can be regenerated by with N2 or by heating. The phosphorus content of the treated PC/ABS was reduced to near zero, showing a very high recovery rate of BDP, and the recovered BDP showed thermal stability the same as commercial RDP and chemical purity.
“Recycling of phosphorus-containing plastic based on the dual effects of switchable hydrophilicity solvents”, L. Wang et al., Chemosphere 259 (2020) 127402 https://doi.org/10.1016/j.chemosphere.2020.127402