Solvent separation is a waste plastic separation method that has been widely researched in recent years. This technology primarily leverages the differences in the solubility of various types of plastics in the same solvent to achieve the separation and recovery of different types of waste plastics. Currently, the selection of solvents mainly follows principles such as the similarity of solubility parameters. In 2009, Achilias et al. used solvent dissolution and reprecipitation technology to achieve the recycling of food, pharmaceutical, and detergent packaging materials made of LDPE, HDPE, PP, PS, PVC, and PET. Simultaneously, the research group also conducted tests on the properties of the recycled material, and the study indicated that the properties of the recycled material were essentially consistent with the original materials, with only a few instances of slight degradation.

In 2020, Walker et al. successfully separated PE, EVOH, and PET composite films using solvent methods, obtaining individual components of plastics. Subsequently, Nieminen et al. used solvent methods to separate aluminum foil and plastics in discarded pharmaceutical packaging. In recent years, Sinopec Petrochemical Research Institute has also conducted systematic research on the selective dissolution of plastics. Solvent separation of waste plastics has advantages such as good product adaptability, high quality of separated plastics, and simple operation. However, with the increasing prices of chemical products, solvent costs are also rising, highlighting economic challenges. Additionally, the overall energy consumption issue remains a major difficulty that urgently needs to be addressed in this technology.